Slach/.gitignore

## .gitignore
config.yml
anomalies/
src/github.com
src/gopkg.in
src/golang.org
src/vendor
vendor/
*.log
pkg/
dist/
.vagrant/
.idea/
*.exe
*.dll
*.so
*.dylib

id_rsa


# Test binary, build with `go test -c`
*.test

# Output of the go coverage tool, specifically when used with LiteIDE
*.out

# Project-local glide cache, RE: https://github.com/Masterminds/glide/issues/736
.glide/

## bad_ch_driver_close_connection.go
package main

import (
	"database/sql"
	"fmt"
	"math/rand"
	"sync"
	"time"

	_ "github.com/kshvakov/clickhouse"
	"github.com/rs/zerolog"
	"github.com/rs/zerolog/log"
)

var clickhousePool map[string]*sql.DB
var clickhouseDeadPool map[string]*sql.DB
var clickhouseMutex = sync.Mutex{}

//ConfigType parent ConfigType for basically configuration functionality of CH.PRO Tools
type ConfigType struct {
	Debug      bool
	Clickhouse struct {
		Hosts        []string `yaml:"hosts"`
		HTTPPort     string   `yaml:"http_port"`
		ReadTimeout  uint16
		WriteTimeout uint16
		ClusterName  string
		Database     string
		Username     string
		Password     string
		BlockSize    uint64
	} `yaml:"clickhouse"`
}

//InitClickhousePool create lazy connection for each config.Clickhouse.Host and run ping all hosts every minute goroutine checkClickhousePoolLive
func InitClickhousePool(config *ConfigType) {
	if config.Clickhouse.Hosts == nil || len(config.Clickhouse.Hosts) == 0 {
		log.Fatal().Msg("Empty clickhouse.hosts in settings")
	}
	clickhousePool = map[string]*sql.DB{}
	clickhouseDeadPool = map[string]*sql.DB{}

	for i, mainHost := range config.Clickhouse.Hosts {
		dsn := "tcp://%s/%s?username=%s&password=%s&block_size=%d&debug=%t&read_timeout=%d&write_timeout=%d"
		altHosts := ""

		if len(config.Clickhouse.Hosts) > 1 {
			for j, host := range config.Clickhouse.Hosts {
				if j != i {
					if altHosts == "" {
						altHosts += host
					} else {
						altHosts += "," + host
					}
				}
			}
			dsn += "&altHosts=" + altHosts
		}
		dsn = fmt.Sprintf(
			dsn,
			mainHost,
			config.Clickhouse.Database,
			config.Clickhouse.Username,
			config.Clickhouse.Password,
			config.Clickhouse.BlockSize,
			config.Debug,
			config.Clickhouse.ReadTimeout,
			config.Clickhouse.WriteTimeout,
		)
		log.Debug().Msg(dsn)
		ch, err := sql.Open("clickhouse", dsn)
		if err != nil {
			log.Fatal().Err(err).Msg("InitClickhousePool Open error")
		}
		err = ch.Ping()
		if err != nil {
			log.Fatal().Err(err).Msg("InitClickhousePool Ping error")
		}
		clickhousePool[mainHost] = ch
	}

	go checkClickhousePoolLive()

	log.Debug().Msgf(
		"InitClickhousePool Success with clickhousePool=%v config.Clickhouse.Hosts=%v", clickhousePool, config.Clickhouse.Hosts,
	)

}

func checkClickhousePoolLive() {
	check := func() {
		livePool := map[string]*sql.DB{}
		deadPool := map[string]*sql.DB{}
		pingAllConnection := func(Pool map[string]*sql.DB) {
			for clickhouseHost, conn := range Pool {
				if err := conn.Ping(); err == nil {
					livePool[clickhouseHost] = conn
				} else {
					log.Warn().Str("clickhouseHost", clickhouseHost).Err(err).Msg("some Clickhouse hosts is down")
					deadPool[clickhouseHost] = conn
				}
			}
		}
		pingAllConnection(clickhouseDeadPool)
		pingAllConnection(clickhousePool)
		if len(livePool) < 1 {
			log.Fatal().Msg("All clickhouse hosts is Down")
		}
		clickhouseMutex.Lock()
		defer clickhouseMutex.Unlock()
		clickhouseDeadPool = deadPool
		clickhousePool = livePool
	}
	for {
		check()
		time.Sleep(10 * time.Second)
	}
}

//GetRandomClickhouseConnection get random database/sql instance pointer from live clickhouse connections
func GetRandomClickhouseConnection() *sql.DB {
	clickhouseMutex.Lock()
	defer clickhouseMutex.Unlock()
	i := rand.Intn(len(clickhousePool))
	for k := range clickhousePool {
		if i == 0 {
			return clickhousePool[k]
		}
		i--
	}
	return nil
}

//FetchRowAsMap see https://kylewbanks.com/blog/query-result-to-map-in-golang
func FetchRowAsMap(rows *sql.Rows, cols []string) (m map[string]interface{}, err error) {
	// Create a slice of interface{}'s to represent each column,
	// and a second slice to contain pointers to each item in the columns slice.
	columns := make([]interface{}, len(cols))
	columnPointers := make([]interface{}, len(cols))
	for i := range columns {
		columnPointers[i] = &columns[i]
	}

	// Scan the result into the column pointers...
	if err := rows.Scan(columnPointers...); err != nil {
		return nil, err
	}

	// Create our map, and retrieve the value for each column from the pointers slice,
	// storing it in the map with the name of the column as the key.
	m = make(map[string]interface{}, len(cols))
	for i, colName := range cols {
		val := columnPointers[i].(*interface{})
		m[colName] = *val
	}
	return m, nil
}

func makeQuery() {
	db := GetRandomClickhouseConnection()
	q := "SELECT now() AS nowDate"
	rows, err := db.Query(q)
	if err != nil {
		log.Fatal().Str("q", q).Err(err).Msg("makeQuery Query Error")
	}
	cols, _ := rows.Columns()
	for rows.Next() {
		r, err := FetchRowAsMap(rows, cols)
		if err != nil {
			log.Fatal().Str("q", q).Err(err).Msg("makeQuery Fetch Error")
		}
		log.Info().Time("nowDate", r["nowDate"].(time.Time)).Msg("makeQuery OK")
	}
}

func main() {
	cfg := ConfigType{}
	cfg.Clickhouse.Hosts = []string{"localhost:9000"}
	cfg.Clickhouse.ClusterName = "default"
	cfg.Clickhouse.ReadTimeout = 10
	cfg.Clickhouse.WriteTimeout = 10
	cfg.Debug = true
	InitClickhousePool(&cfg)
	zerolog.SetGlobalLevel(zerolog.DebugLevel)
	for {
		makeQuery()
		log.Info().Msg("Pause 1 min")
		time.Sleep(60 * time.Second)
	}
}

## config.xml
<?xml version="1.0"?>
<yandex>
    <logger>
        <level>trace</level>
        <log>/var/log/clickhouse-server/clickhouse-server.log</log>
        <errorlog>/var/log/clickhouse-server/clickhouse-server.err.log</errorlog>
        <size>100M</size>
        <count>1</count>
    </logger>


    <http_port>8123</http_port>
        <!--
    <https_port>8443</https_port>
    -->
    <!-- Used only with https_port. Full ssl options list: https://github.com/yandex/ClickHouse/blob/master/contrib/libpoco/NetSSL_OpenSSL/include/Poco/Net/SSLManager.h#L71 -->
    <openSSL>
        <server>
            <!-- openssl req -subj "/CN=localhost" -new -newkey rsa:2048 -days 365 -nodes -x509 -keyout /etc/clickhouse-server/server.key -out /etc/clickhouse-server/server.crt -->
            <certificateFile>/etc/clickhouse-server/server.crt</certificateFile>
            <privateKeyFile>/etc/clickhouse-server/server.key</privateKeyFile>
            <!-- openssl dhparam -out /etc/clickhouse-server/dhparam.pem 4096 -->
            <dhParamsFile>/etc/clickhouse-server/dhparam.pem</dhParamsFile>
            <verificationMode>none</verificationMode>
            <loadDefaultCAFile>true</loadDefaultCAFile>
            <cacheSessions>true</cacheSessions>
            <disableProtocols>sslv2,sslv3</disableProtocols>
            <preferServerCiphers>true</preferServerCiphers>
        </server>
        <client>
            <loadDefaultCAFile>true</loadDefaultCAFile>
            <cacheSessions>true</cacheSessions>
            <disableProtocols>sslv2,sslv3</disableProtocols>
            <preferServerCiphers>true</preferServerCiphers>
            <!-- Use for self-signed: <verificationMode>none</verificationMode> -->
            <invalidCertificateHandler>
                <!-- Use for self-signed: <name>AcceptCertificateHandler</name> -->
                <name>RejectCertificateHandler</name>
            </invalidCertificateHandler>
        </client>
    </openSSL>

    <!-- Default root page on http[s] server. For example load UI from https://tabix.io/ when opening http://localhost:8123 -->
    <!--
    <http_server_default_response><![CDATA[<html ng-app="SMI2"><head><base href="http://ui.tabix.io/"></head><body><div ui-view="" class="content-ui"></div><script src="http://loader.tabix.io/master.js"></script></body></html>]]></http_server_default_response>
    -->

    <tcp_port>9000</tcp_port>

    <!-- Port for communication between replicas. Used for data exchange. -->
    <interserver_http_port>9009</interserver_http_port>

    <!-- Hostname that is used by other replicas to request this server.
         If not specified, than it is determined analoguous to 'hostname -f' command.
         This setting could be used to switch replication to another network interface.
      -->
    <!--
    <interserver_http_host>example.yandex.ru</interserver_http_host>
    -->

    <!-- Listen specified host. use :: (wildcard IPv6 address), if you want to accept connections both with IPv4 and IPv6 from everywhere. -->
    <!-- <listen_host>::</listen_host> -->
    <listen_host>0.0.0.0</listen_host>

    <max_connections>4096</max_connections>
    <keep_alive_timeout>3</keep_alive_timeout>

    <!-- Maximum number of concurrent queries. -->
    <max_concurrent_queries>100</max_concurrent_queries>

    <!-- Set limit on number of open files (default: maximum). This setting makes sense on Mac OS X because getrlimit() fails to retrieve
         correct maximum value. -->
    <!-- <max_open_files>262144</max_open_files> -->

    <!-- Size of cache of uncompressed blocks of data, used in tables of MergeTree family.
         In bytes. Cache is single for server. Memory is allocated only on demand.
         Cache is used when 'use_uncompressed_cache' user setting turned on (off by default).
         Uncompressed cache is advantageous only for very short queries and in rare cases.
      -->
    <uncompressed_cache_size>8589934592</uncompressed_cache_size>

    <!-- Approximate size of mark cache, used in tables of MergeTree family.
         In bytes. Cache is single for server. Memory is allocated only on demand.
         You should not lower this value.
      -->
    <mark_cache_size>5368709120</mark_cache_size>


    <!-- Path to data directory, with trailing slash. -->
    <path>/var/lib/clickhouse/</path>

    <!-- Path to temporary data for processing hard queries. -->
    <tmp_path>/var/lib/clickhouse/tmp/</tmp_path>

    <!-- Path to configuration file with users, access rights, profiles of settings, quotas. -->
    <users_config>users.xml</users_config>

    <!-- Default profile of settings.. -->
    <default_profile>default</default_profile>

    <!-- Default database. -->
    <default_database>default</default_database>

    <!-- Server time zone could be set here.

         Time zone is used when converting between String and DateTime types,
          when printing DateTime in text formats and parsing DateTime from text,
          it is used in date and time related functions, if specific time zone was not passed as an argument.

         Time zone is specified as identifier from IANA time zone database, like UTC or Africa/Abidjan.
         If not specified, system time zone at server startup is used.

         Please note, that server could display time zone alias instead of specified name.
         Example: W-SU is an alias for Europe/Moscow and Zulu is an alias for UTC.
    -->
        <!-- <timezone>Europe/Moscow</timezone> -->

        <!-- You can specify umask here (see "man umask"). Server will apply it on startup.
         Number is always parsed as octal. Default umask is 027 (other users cannot read logs, data files, etc; group can only read).
    -->
        <!-- <umask>022</umask> -->
        <!-- Configuration of clusters that could be used in Distributed tables.
         https://clickhouse.yandex/reference_en.html#Distributed -->
    <remote_servers>
        <metrika2clickhouse>
            <shard>
                <weight>1</weight>
                <internal_replication>false</internal_replication>
                <replica>
                    <host>localhost</host>
                    <port>9000</port>
                </replica>
            </shard>
            <!--
            <shard>
                <weight>1</weight>
                <internal_replication>false</internal_replication>
                <replica>
                    <host>clickhouse-ru-1.local</host>
                    <port>9000</port>
                </replica>
                <replica>
                    <host>clickhouse-ru-2.local</host>
                    <port>9000</port>
                </replica>
            </shard>
            <shard>
                <weight>1</weight>
                <internal_replication>false</internal_replication>
                <replica>
                    <host>clickhouse-eu-1.local</host>
                    <port>9000</port>
                </replica>
                <replica>
                    <host>clickhouse-eu-2.local</host>
                    <port>9000</port>
                </replica>
            </shard>
            <shard>
                <weight>1</weight>
                <internal_replication>false</internal_replication>
                <replica>
                    <host>clickhouse-us-1.local</host>
                    <port>9000</port>
                </replica>
                <replica>
                    <host>clickhouse-us-2.local</host>
                    <port>9000</port>
                </replica>
            </shard>
            -->
        </metrika2clickhouse>
    </remote_servers>


    <!-- If element has 'incl' attribute, then for it's value will be used corresponding substitution from another file.
         By default, path to file with substitutions is /etc/metrika.xml. It could be changed in config in 'include_from' element.
         Values for substitutions are specified in /yandex/name_of_substitution elements in that file.
      -->

    <!-- ZooKeeper is used to store metadata about replicas, when using Replicated tables.
         Optional. If you don't use replicated tables, you could omit that.

         See https://clickhouse.yandex/reference_en.html#Data%20replication
    <zookeeper>
        <node index="1">
            <host>zookeeper</host>
            <port>2181</port>
        </node>
    </zookeeper>
    -->

    <!-- Substitutions for parameters of replicated tables.
          Optional. If you don't use replicated tables, you could omit that.

         See https://clickhouse.yandex/reference_en.html#Creating%20replicated%20tables
      -->
    <macros incl="macros" optional="true"/>


    <!-- Reloading interval for embedded dictionaries, in seconds. Default: 3600. -->
    <builtin_dictionaries_reload_interval>3600</builtin_dictionaries_reload_interval>


    <!-- Maximum session timeout, in seconds. Default: 3600. -->
    <max_session_timeout>3600</max_session_timeout>


    <!-- Default session timeout, in seconds. Default: 60. -->
    <default_session_timeout>60</default_session_timeout>

<!-- Sending data to Graphite for monitoring. Several sections can be defined. -->
    <!--
        interval - send every X second
        root_path - prefix for keys
        metrics - send data from table system.metrics
        events - send data from table system.events
        asynchronous_metrics - send data from table system.asynchronous_metrics
    -->
    <use_graphite>false</use_graphite>
    <!--
    <graphite>
        <host>localhost</host>
        <port>42000</port>
        <timeout>0.1</timeout>
        <interval>60</interval>
        <root_path>one_min</root_path>

        <metrics>true</metrics>
        <events>true</events>
        <asynchronous_metrics>true</asynchronous_metrics>
    </graphite>
    <graphite>
        <host>localhost</host>
        <port>42000</port>
        <timeout>0.1</timeout>
        <interval>1</interval>
        <root_path>one_sec</root_path>

        <metrics>true</metrics>
        <events>true</events>
        <asynchronous_metrics>false</asynchronous_metrics>
    </graphite>
-->

        <!-- Query log. Used only for queries with setting log_queries = 1. -->
    <query_log>
        <!-- What table to insert data. If table is not exist, it will be created.
             When query log structure is changed after system update,
              then old table will be renamed and new table will be created automatically.
        -->
        <database>system</database>
        <table>query_log</table>

        <!-- Interval of flushing data. -->
        <flush_interval_milliseconds>7500</flush_interval_milliseconds>
    </query_log>


    <!-- Uncomment if use part_log
    <part_log>
        <database>system</database>
        <table>part_log</table>

        <flush_interval_milliseconds>7500</flush_interval_milliseconds>
    </part_log>
    -->


    <!-- Parameters for embedded dictionaries, used in Yandex.Metrica.
         See https://clickhouse.yandex/reference_en.html#Internal%20dictionaries
    -->

    <!-- Path to file with region hierarchy. -->
    <!-- <path_to_regions_hierarchy_file>/opt/geo/regions_hierarchy.txt</path_to_regions_hierarchy_file> -->

    <!-- Path to directory with files containing names of regions -->
    <!-- <path_to_regions_names_files>/opt/geo/</path_to_regions_names_files> -->


    <!-- Configuration of external dictionaries. See:
         https://clickhouse.yandex/reference_en.html#External%20Dictionaries
    -->
    <dictionaries_config>*_dictionary.xml</dictionaries_config>


    <!-- Uncomment if you want data to be compressed 30-100% better.
         Don't do that if you just started using ClickHouse.
      -->
    <compression incl="clickhouse_compression">
            <!-- Set of variants. Checked in order. Last matching case wins. If nothing matches, lz4 will be used. -->
            <case>
                <!-- Conditions. All must be satisfied. Some conditions may be omitted. -->
                <min_part_size>10000000000</min_part_size>		<!-- Min part size in bits. -->
                <min_part_size_ratio>0.01</min_part_size_ratio>	<!-- Min size of part relative to whole table size. -->

                <!-- What compression method to use. -->
                <method>zstd</method>	<!-- Keep in mind that zstd compression library is highly experimental. -->
            </case>
    </compression>

    <resharding>
        <task_queue_path>/clickhouse/task_queue</task_queue_path>
    </resharding>

    <!-- Allow to execute distributed DDL queries (CREATE, DROP, ALTER, RENAME) on cluster.
         Works only if ZooKeeper is enabled. Comment it if such functionality isn't required. -->
    <distributed_ddl>
        <!-- Path in ZooKeeper to queue with DDL queries -->
        <path>/clickhouse/task_queue/ddl</path>
    </distributed_ddl>

    <!-- Settings to fine tune MergeTree tables. See documentation in source code, in MergeTreeSettings.h -->
    <!--
    <merge_tree>
        <max_suspicious_broken_parts>5</max_suspicious_broken_parts>
    </merge_tree>
    -->

    <!-- Protection from accidental DROP.
         If size of a MergeTree table is greater than max_table_size_to_drop (in bytes) than table could not be dropped with any DROP query.
         If you want do delete one table and don't want to restart clickhouse-server, you could create special file <clickhouse-path>/flags/force_drop_table and make DROP once.
         By default max_table_size_to_drop is 50GB, max_table_size_to_drop=0 allows to DROP any tables.
         Uncomment to disable protection.
    -->
    <!-- <max_table_size_to_drop>0</max_table_size_to_drop> -->

    <!-- Example of parameters for GraphiteMergeTree table engine -->
    <graphite_rollup_example>
        <pattern>
            <regexp>click_cost</regexp>
            <function>any</function>
            <retention>
                <age>0</age>
                <precision>3600</precision>
            </retention>
            <retention>
                <age>86400</age>
                <precision>60</precision>
            </retention>
        </pattern>
        <default>
            <function>max</function>
            <retention>
                <age>0</age>
                <precision>60</precision>
            </retention>
            <retention>
                <age>3600</age>
                <precision>300</precision>
            </retention>
            <retention>
                <age>86400</age>
                <precision>3600</precision>
            </retention>
        </default>
    </graphite_rollup_example>
</yandex>

## output.log
{"time":"2018-01-17T05:09:45Z","level":"debug","message":"tcp://localhost:9000/?username=&password=&block_size=0&debug=true"}
[clickhouse]host(s)=localhost:9000, database=default, username=default
[clickhouse][dial] secure=false, skip_verify=true, strategy=random, ident=1, server=0 -> 127.0.0.1:9000
[clickhouse][connect=1][hello] -> Golang SQLDriver 1.1.54213
[clickhouse][connect=1][hello] <- ClickHouse 1.1.54327 (Zulu)
[clickhouse][connect=1]-> ping
[clickhouse][connect=1][process] <- pong
{"time":"2018-01-17T05:09:45Z","level":"debug","message":"InitClickhousePool Success with clickhousePool=map[localhost:9000:0xc42009e3c0] config.Clickhouse.Host
s=[localhost:9000]"}
[clickhouse][connect=1][prepare] SELECT now() AS nowDate
[clickhouse][connect=1][send query] SELECT now() AS nowDate
[clickhouse]host(s)=localhost:9000, database=default, username=default
[clickhouse][connect=1][read meta] <- data: packet=1, columns=1, rows=0
[clickhouse][dial] secure=false, skip_verify=true, strategy=random, ident=2, server=0 -> 127.0.0.1:9000
[clickhouse][connect=1][rows] <- data: packet=1, columns=1, rows=1, elapsed=14.135чs
[clickhouse][connect=1][rows] <- profiling: rows=1, bytes=12, blocks=1
[clickhouse][connect=1][rows] <- progress: rows=1, bytes=1, total rows=0
[clickhouse][connect=1][rows] <- data: packet=1, columns=0, rows=0, elapsed=10.058чs
[clickhouse][connect=1][rows] <- end of stream
{"time":"2018-01-17T05:09:45Z","level":"info","nowDate":"2018-01-17T05:09:45Z","message":"makeQuery OK"}
[clickhouse][connect=1][rows] close
[clickhouse][connect=1][stmt] close
{"time":"2018-01-17T05:09:45Z","level":"info","message":"Pause 1 min"}
[clickhouse][connect=2][hello] -> Golang SQLDriver 1.1.54213
[clickhouse][connect=2][hello] <- ClickHouse 1.1.54327 (Zulu)
[clickhouse][connect=2]-> ping
[clickhouse][connect=2][process] <- pong
[clickhouse][connect=1]-> ping
[clickhouse][connect=1][process] <- pong
[clickhouse][connect=2]-> ping
[clickhouse][connect=2][process] <- pong
[clickhouse][connect=1]-> ping
[clickhouse][connect=1][process] <- pong
[clickhouse][connect=2]-> ping
[clickhouse][connect=2][process] <- pong
[clickhouse][connect=1]-> ping
[clickhouse][connect=1][process] <- pong
[clickhouse][connect=2][prepare] SELECT now() AS nowDate
[clickhouse][connect=2][send query] SELECT now() AS nowDate
[clickhouse][connect=2][read meta] <- data: packet=1, columns=1, rows=0
[clickhouse][connect=2][rows] <- data: packet=1, columns=1, rows=1, elapsed=32.319чs
{"time":"2018-01-17T05:10:45Z","level":"info","nowDate":"2018-01-17T05:10:45Z","message":"makeQuery OK"}
[clickhouse][connect=2][rows] <- profiling: rows=1, bytes=12, blocks=1
[clickhouse][connect=2][rows] <- progress: rows=1, bytes=1, total rows=0
[clickhouse][connect=2][rows] <- data: packet=1, columns=0, rows=0, elapsed=9.759чs
[clickhouse][connect=2][rows] <- end of stream
[clickhouse][connect=2][rows] close
[clickhouse][connect=2][stmt] close
{"time":"2018-01-17T05:10:45Z","level":"info","message":"Pause 1 min"}
[clickhouse][connect=1]-> ping
[clickhouse][connect=1][connect] write error: write tcp 127.0.0.1:36612->127.0.0.1:9000: i/o timeout
{"time":"2018-01-17T05:10:45Z","level":"warn","clickhouseHost":"localhost:9000","error":"driver: bad connection","message":"some Clickhouse hosts is down"}
{"time":"2018-01-17T05:10:45Z","level":"fatal","message":"All clickhouse hosts is Down"}
exit status 1

## running commands.sh
vagrant ssh
ubuntu@local-bad-clickhouse-driver-clickhouse-pro:/home/ubuntu$ cd /vagrant
ubuntu@local-bad-clickhouse-driver-clickhouse-pro:/vagrant$ export GOPATH=/home/ubuntu/go
ubuntu@local-bad-clickhouse-driver-clickhouse-pro:/vagrant$ go get bad_ch_driver_close_connection.go
ubuntu@local-bad-clickhouse-driver-clickhouse-pro:/vagrant$ go run bad_ch_driver_close_connection.go

## users.xml
<?xml version="1.0"?>
<yandex>
    <!-- Profiles of settings. -->
    <profiles>
        <!-- Default settings. -->
        <default>
            <!-- Maximum memory usage for processing single query, in bytes 2G. -->
            <max_memory_usage>2000000000</max_memory_usage>
			<max_memory_usage_for_user>2000000000</max_memory_usage_for_user>
			<max_memory_usage_for_all_queries>2000000000</max_memory_usage_for_all_queries>
			<background_pool_size>2</background_pool_size>
			<!--
			<min_insert_block_size_bytes>67108864</min_insert_block_size_bytes>
			<max_insert_block_size>524288</max_insert_block_size>
			<min_insert_block_size_rows>10000</min_insert_block_size_rows>
			-->

            <!-- Use cache of uncompressed blocks of data. Meaningful only for processing many of very short queries. -->
            <use_uncompressed_cache>1</use_uncompressed_cache>

            <!-- How to choose between replicas during distributed query processing.
                 random - choose random replica from set of replicas with minimum number of errors
                 nearest_hostname - from set of replicas with minimum number of errors, choose replica
                  with minumum number of different symbols between replica's hostname and local hostname
                  (Hamming distance).
                 in_order - first live replica is choosen in specified order.
            -->
            <load_balancing>random</load_balancing>
        </default>

        <!-- Profile that allows only read queries. -->
        <readonly>
            <readonly>1</readonly>
        </readonly>
    </profiles>

    <!-- Users and ACL. -->
    <users>
        <!-- If user name was not specified, 'default' user is used. -->
        <default>
            <!-- Password could be specified in plaintext or in SHA256 (in hex format).

                 If you want to specify password in plaintext (not recommended), place it in 'password' element.
                 Example: <password>qwerty</password>.
                 Password could be empty.

                 If you want to specify SHA256, place it in 'password_sha256_hex' element.
                 Example: <password_sha256_hex>65e84be33532fb784c48129675f9eff3a682b27168c0ea744b2cf58ee02337c5</password_sha256_hex>

                 How to generate decent password:
                 Execute: PASSWORD=$(base64 < /dev/urandom | head -c8); echo "$PASSWORD"; echo -n "$PASSWORD" | sha256sum | tr -d '-'
                 In first line will be password and in second - corresponding SHA256.
            -->
            <password></password>

            <!-- List of networks with open access.

                 To open access from everywhere, specify:
                    <ip>::/0</ip>

                 To open access only from localhost, specify:
                    <ip>::1</ip>
                    <ip>127.0.0.1</ip>

                 Each element of list has one of the following forms:
                 <ip> IP-address or network mask. Examples: 213.180.204.3 or 10.0.0.1/8 or 2a02:6b8::3 or 2a02:6b8::3/64.
                 <host> Hostname. Example: server01.yandex.ru.
                     To check access, DNS query is performed, and all received addresses compared to peer address.
                 <host_regexp> Regular expression for host names. Example, ^server\d\d-\d\d-\d\.yandex\.ru$
                     To check access, DNS PTR query is performed for peer address and then regexp is applied.
                     Then, for result of PTR query, another DNS query is performed and all received addresses compared to peer address.
                     Strongly recommended that regexp is ends with $
                 All results of DNS requests are cached till server restart.
            -->
            <networks incl="networks" replace="replace">
                <ip>::/0</ip>
            </networks>

            <!-- Settings profile for user. -->
            <profile>default</profile>

            <!-- Quota for user. -->
            <quota>default</quota>
        </default>

        <!-- Example of user with readonly access. -->
        <readonly>
            <password></password>
            <networks incl="networks" replace="replace">
                <ip>::1</ip>
                <ip>127.0.0.1</ip>
            </networks>
            <profile>readonly</profile>
            <quota>default</quota>
        </readonly>
    </users>

    <!-- Quotas. -->
    <quotas>
        <!-- Name of quota. -->
        <default>
            <!-- Limits for time interval. You could specify many intervals with different limits. -->
            <interval>
                <!-- Length of interval. -->
                <duration>3600</duration>

                <!-- No limits. Just calculate resource usage for time interval. -->
                <queries>0</queries>
                <errors>0</errors>
                <result_rows>0</result_rows>
                <read_rows>0</read_rows>
                <execution_time>0</execution_time>
            </interval>
        </default>
    </quotas>
</yandex>

## Vagrantfile
# -*- mode: ruby -*-
# vi: set ft=ruby :
Vagrant.configure(2) do |config|
	config.vm.box = "ubuntu/xenial64"
	config.vm.box_check_update = false

	config.hostmanager.enabled = true
	config.hostmanager.manage_host = true
	config.hostmanager.ignore_private_ip = false
	config.hostmanager.include_offline = false

	config.vm.provider "virtualbox" do |vb|
		vb.gui = false
		vb.memory = "1024"
		vb.customize ["setextradata", :id, "VBoxInternal2/SharedFoldersEnableSymlinksCreate/vagrant", "1"]
	end

	config.vm.define :bad_clickhouse_driver do |bad_clickhouse_driver|
    bad_clickhouse_driver.vm.synced_folder "./", "/home/ubuntu/go/src/gist.github.com/d56062af1332ff6322f74100dbcc8e63"
		bad_clickhouse_driver.vm.host_name = "local-bad-clickhouse-driver-clickhouse-pro"
		bad_clickhouse_driver.hostmanager.aliases = ["local.bad-clickhouse-driver.clickhouse.pro"]
		bad_clickhouse_driver.vm.network "private_network", ip: "172.16.2.77"
		bad_clickhouse_driver.vm.provision "shell", inline: <<-SHELL
			set -xeuo pipefail
			export DEBIAN_FRONTEND=noninteractive
			export GOPATH=/home/ubuntu/go
			apt-get update
			apt-get install -y apt-transport-https software-properties-common aptitude
			# clickhouse
			apt-key adv --keyserver keyserver.ubuntu.com --recv-keys E0C56BD4
			# gophers
			apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 136221EE520DDFAF0A905689B9316A7BC7917B12
			add-apt-repository "deb http://repo.yandex.ru/clickhouse/xenial/ stable main"
			add-apt-repository ppa:gophers/archive
			apt-get update
			apt-get install -y golang-1.9
			apt-get install -y clickhouse-server-common clickhouse-client
			cp -fv /vagrant/config.xml /etc/clickhouse-server/
			cp -fv /vagrant/users.xml /etc/clickhouse-server/
			ln -nvsf /usr/lib/go-1.9/bin/go /bin/go
			ln -nvsf /usr/lib/go-1.9/bin/gofmt /bin/gofmt
			systemctl restart clickhouse-server
			mkdir -p /home/ubuntu/go/bin
			bash -c "cd /home/ubuntu/go/src/gist.github.com/d56062af1332ff6322f74100dbcc8e63 && go get -v ./..."
			cd /vagrant && GOPATH=/home/ubuntu/go go run bad_ch_driver_close_connection.go
			set +x

			echo "bad_clickhouse_driver PROVISIONING DONE, use folloding scenario for reproduce bug"
			echo "#  vagrant ssh bad_clickhouse_driver"
			echo "#  sudo bash -c \\\"cd /vagrant && GOPATH=/home/ubuntu/go go run bad_ch_driver_close_connection.go \\\""
			echo "Good Luck ;)"
		SHELL
	end
end
	config.yml
	anomalies/
	src/github.com
	src/gopkg.in
	src/golang.org
	src/vendor
	vendor/
	*.log
	pkg/
	dist/
	.vagrant/
	.idea/
	*.exe
	*.dll
	*.so
	*.dylib

	id_rsa



	# Test binary, build with `go test -c`
	*.test

	# Output of the go coverage tool, specifically when used with LiteIDE
	*.out

	# Project-local glide cache, RE: https://github.com/Masterminds/glide/issues/736
	.glide/
	package main

	import (
	"database/sql"
	"fmt"
	"math/rand"
	"sync"
	"time"

	_ "github.com/kshvakov/clickhouse"
	"github.com/rs/zerolog"
	"github.com/rs/zerolog/log"
	)

	var clickhousePool map[string]*sql.DB
	var clickhouseDeadPool map[string]*sql.DB
	var clickhouseMutex = sync.Mutex{}

	//ConfigType parent ConfigType for basically configuration functionality of CH.PRO Tools
	type ConfigType struct {
	Debug bool
	Clickhouse struct {
	Hosts []string `yaml:"hosts"`
	HTTPPort string `yaml:"http_port"`
	ReadTimeout uint16
	WriteTimeout uint16
	ClusterName string
	Database string
	Username string
	Password string
	BlockSize uint64
	} `yaml:"clickhouse"`
	}

	//InitClickhousePool create lazy connection for each config.Clickhouse.Host and run ping all hosts every minute goroutine checkClickhousePoolLive
	func InitClickhousePool(config *ConfigType) {
	if config.Clickhouse.Hosts == nil \|\| len(config.Clickhouse.Hosts) == 0 {
	log.Fatal().Msg("Empty clickhouse.hosts in settings")
	}
	clickhousePool = map[string]*sql.DB{}
	clickhouseDeadPool = map[string]*sql.DB{}

	for i, mainHost := range config.Clickhouse.Hosts {
	dsn := "tcp://%s/%s?username=%s&password=%s&block_size=%d&debug=%t&read_timeout=%d&write_timeout=%d"
	altHosts := ""

	if len(config.Clickhouse.Hosts) > 1 {
	for j, host := range config.Clickhouse.Hosts {
	if j != i {
	if altHosts == "" {
	altHosts += host
	} else {
	altHosts += "," + host
	}
	}
	}
	dsn += "&altHosts=" + altHosts
	}
	dsn = fmt.Sprintf(
	dsn,
	mainHost,
	config.Clickhouse.Database,
	config.Clickhouse.Username,
	config.Clickhouse.Password,
	config.Clickhouse.BlockSize,
	config.Debug,
	config.Clickhouse.ReadTimeout,
	config.Clickhouse.WriteTimeout,
	)
	log.Debug().Msg(dsn)
	ch, err := sql.Open("clickhouse", dsn)
	if err != nil {
	log.Fatal().Err(err).Msg("InitClickhousePool Open error")
	}
	err = ch.Ping()
	if err != nil {
	log.Fatal().Err(err).Msg("InitClickhousePool Ping error")
	}
	clickhousePool[mainHost] = ch
	}

	go checkClickhousePoolLive()

	log.Debug().Msgf(
	"InitClickhousePool Success with clickhousePool=%v config.Clickhouse.Hosts=%v", clickhousePool, config.Clickhouse.Hosts,
	)

	}

	func checkClickhousePoolLive() {
	check := func() {
	livePool := map[string]*sql.DB{}
	deadPool := map[string]*sql.DB{}
	pingAllConnection := func(Pool map[string]*sql.DB) {
	for clickhouseHost, conn := range Pool {
	if err := conn.Ping(); err == nil {
	livePool[clickhouseHost] = conn
	} else {
	log.Warn().Str("clickhouseHost", clickhouseHost).Err(err).Msg("some Clickhouse hosts is down")
	deadPool[clickhouseHost] = conn
	}
	}
	}
	pingAllConnection(clickhouseDeadPool)
	pingAllConnection(clickhousePool)
	if len(livePool) < 1 {
	log.Fatal().Msg("All clickhouse hosts is Down")
	}
	clickhouseMutex.Lock()
	defer clickhouseMutex.Unlock()
	clickhouseDeadPool = deadPool
	clickhousePool = livePool
	}
	for {
	check()
	time.Sleep(10 * time.Second)
	}
	}

	//GetRandomClickhouseConnection get random database/sql instance pointer from live clickhouse connections
	func GetRandomClickhouseConnection() *sql.DB {
	clickhouseMutex.Lock()
	defer clickhouseMutex.Unlock()
	i := rand.Intn(len(clickhousePool))
	for k := range clickhousePool {
	if i == 0 {
	return clickhousePool[k]
	}
	i--
	}
	return nil
	}

	//FetchRowAsMap see https://kylewbanks.com/blog/query-result-to-map-in-golang
	func FetchRowAsMap(rows *sql.Rows, cols []string) (m map[string]interface{}, err error) {
	// Create a slice of interface{}'s to represent each column,
	// and a second slice to contain pointers to each item in the columns slice.
	columns := make([]interface{}, len(cols))
	columnPointers := make([]interface{}, len(cols))
	for i := range columns {
	columnPointers[i] = &columns[i]
	}

	// Scan the result into the column pointers...
	if err := rows.Scan(columnPointers...); err != nil {
	return nil, err
	}

	// Create our map, and retrieve the value for each column from the pointers slice,
	// storing it in the map with the name of the column as the key.
	m = make(map[string]interface{}, len(cols))
	for i, colName := range cols {
	val := columnPointers[i].(*interface{})
	m[colName] = *val
	}
	return m, nil
	}

	func makeQuery() {
	db := GetRandomClickhouseConnection()
	q := "SELECT now() AS nowDate"
	rows, err := db.Query(q)
	if err != nil {
	log.Fatal().Str("q", q).Err(err).Msg("makeQuery Query Error")
	}
	cols, _ := rows.Columns()
	for rows.Next() {
	r, err := FetchRowAsMap(rows, cols)
	if err != nil {
	log.Fatal().Str("q", q).Err(err).Msg("makeQuery Fetch Error")
	}
	log.Info().Time("nowDate", r["nowDate"].(time.Time)).Msg("makeQuery OK")
	}
	}

	func main() {
	cfg := ConfigType{}
	cfg.Clickhouse.Hosts = []string{"localhost:9000"}
	cfg.Clickhouse.ClusterName = "default"
	cfg.Clickhouse.ReadTimeout = 10
	cfg.Clickhouse.WriteTimeout = 10
	cfg.Debug = true
	InitClickhousePool(&cfg)
	zerolog.SetGlobalLevel(zerolog.DebugLevel)
	for {
	makeQuery()
	log.Info().Msg("Pause 1 min")
	time.Sleep(60 * time.Second)
	}
	}
	<?xml version="1.0"?>
	<yandex>
	<logger>
	<level>trace</level>
	<log>/var/log/clickhouse-server/clickhouse-server.log</log>
	<errorlog>/var/log/clickhouse-server/clickhouse-server.err.log</errorlog>
	<size>100M</size>
	<count>1</count>
	</logger>


	<http_port>8123</http_port>
	<!--
	<https_port>8443</https_port>
	-->
	<!-- Used only with https_port. Full ssl options list: https://github.com/yandex/ClickHouse/blob/master/contrib/libpoco/NetSSL_OpenSSL/include/Poco/Net/SSLManager.h#L71 -->
	<openSSL>
	<server>
	<!-- openssl req -subj "/CN=localhost" -new -newkey rsa:2048 -days 365 -nodes -x509 -keyout /etc/clickhouse-server/server.key -out /etc/clickhouse-server/server.crt -->
	<certificateFile>/etc/clickhouse-server/server.crt</certificateFile>
	<privateKeyFile>/etc/clickhouse-server/server.key</privateKeyFile>
	<!-- openssl dhparam -out /etc/clickhouse-server/dhparam.pem 4096 -->
	<dhParamsFile>/etc/clickhouse-server/dhparam.pem</dhParamsFile>
	<verificationMode>none</verificationMode>
	<loadDefaultCAFile>true</loadDefaultCAFile>
	<cacheSessions>true</cacheSessions>
	<disableProtocols>sslv2,sslv3</disableProtocols>
	<preferServerCiphers>true</preferServerCiphers>
	</server>
	<client>
	<loadDefaultCAFile>true</loadDefaultCAFile>
	<cacheSessions>true</cacheSessions>
	<disableProtocols>sslv2,sslv3</disableProtocols>
	<preferServerCiphers>true</preferServerCiphers>
	<!-- Use for self-signed: <verificationMode>none</verificationMode> -->
	<invalidCertificateHandler>
	<!-- Use for self-signed: <name>AcceptCertificateHandler</name> -->
	<name>RejectCertificateHandler</name>
	</invalidCertificateHandler>
	</client>
	</openSSL>

	<!-- Default root page on http[s] server. For example load UI from https://tabix.io/ when opening http://localhost:8123 -->
	<!--
	<http_server_default_response><![CDATA[<html ng-app="SMI2"><head><base href="http://ui.tabix.io/"></head><body><div ui-view="" class="content-ui"></div><script src="http://loader.tabix.io/master.js"></script></body></html>]]></http_server_default_response>
	-->

	<tcp_port>9000</tcp_port>

	<!-- Port for communication between replicas. Used for data exchange. -->
	<interserver_http_port>9009</interserver_http_port>

	<!-- Hostname that is used by other replicas to request this server.
	If not specified, than it is determined analoguous to 'hostname -f' command.
	This setting could be used to switch replication to another network interface.
	-->
	<!--
	<interserver_http_host>example.yandex.ru</interserver_http_host>
	-->

	<!-- Listen specified host. use :: (wildcard IPv6 address), if you want to accept connections both with IPv4 and IPv6 from everywhere. -->
	<!-- <listen_host>::</listen_host> -->
	<listen_host>0.0.0.0</listen_host>

	<max_connections>4096</max_connections>
	<keep_alive_timeout>3</keep_alive_timeout>

	<!-- Maximum number of concurrent queries. -->
	<max_concurrent_queries>100</max_concurrent_queries>

	<!-- Set limit on number of open files (default: maximum). This setting makes sense on Mac OS X because getrlimit() fails to retrieve
	correct maximum value. -->
	<!-- <max_open_files>262144</max_open_files> -->

	<!-- Size of cache of uncompressed blocks of data, used in tables of MergeTree family.
	In bytes. Cache is single for server. Memory is allocated only on demand.
	Cache is used when 'use_uncompressed_cache' user setting turned on (off by default).
	Uncompressed cache is advantageous only for very short queries and in rare cases.
	-->
	<uncompressed_cache_size>8589934592</uncompressed_cache_size>

	<!-- Approximate size of mark cache, used in tables of MergeTree family.
	In bytes. Cache is single for server. Memory is allocated only on demand.
	You should not lower this value.
	-->
	<mark_cache_size>5368709120</mark_cache_size>


	<!-- Path to data directory, with trailing slash. -->
	<path>/var/lib/clickhouse/</path>

	<!-- Path to temporary data for processing hard queries. -->
	<tmp_path>/var/lib/clickhouse/tmp/</tmp_path>

	<!-- Path to configuration file with users, access rights, profiles of settings, quotas. -->
	<users_config>users.xml</users_config>

	<!-- Default profile of settings.. -->
	<default_profile>default</default_profile>

	<!-- Default database. -->
	<default_database>default</default_database>

	<!-- Server time zone could be set here.

	Time zone is used when converting between String and DateTime types,
	when printing DateTime in text formats and parsing DateTime from text,
	it is used in date and time related functions, if specific time zone was not passed as an argument.

	Time zone is specified as identifier from IANA time zone database, like UTC or Africa/Abidjan.
	If not specified, system time zone at server startup is used.

	Please note, that server could display time zone alias instead of specified name.
	Example: W-SU is an alias for Europe/Moscow and Zulu is an alias for UTC.
	-->
	<!-- <timezone>Europe/Moscow</timezone> -->

	<!-- You can specify umask here (see "man umask"). Server will apply it on startup.
	Number is always parsed as octal. Default umask is 027 (other users cannot read logs, data files, etc; group can only read).
	-->
	<!-- <umask>022</umask> -->
	<!-- Configuration of clusters that could be used in Distributed tables.
	https://clickhouse.yandex/reference_en.html#Distributed -->
	<remote_servers>
	<metrika2clickhouse>
	<shard>
	<weight>1</weight>
	<internal_replication>false</internal_replication>
	<replica>
	<host>localhost</host>
	<port>9000</port>
	</replica>
	</shard>
	<!--
	<shard>
	<weight>1</weight>
	<internal_replication>false</internal_replication>
	<replica>
	<host>clickhouse-ru-1.local</host>
	<port>9000</port>
	</replica>
	<replica>
	<host>clickhouse-ru-2.local</host>
	<port>9000</port>
	</replica>
	</shard>
	<shard>
	<weight>1</weight>
	<internal_replication>false</internal_replication>
	<replica>
	<host>clickhouse-eu-1.local</host>
	<port>9000</port>
	</replica>
	<replica>
	<host>clickhouse-eu-2.local</host>
	<port>9000</port>
	</replica>
	</shard>
	<shard>
	<weight>1</weight>
	<internal_replication>false</internal_replication>
	<replica>
	<host>clickhouse-us-1.local</host>
	<port>9000</port>
	</replica>
	<replica>
	<host>clickhouse-us-2.local</host>
	<port>9000</port>
	</replica>
	</shard>
	-->
	</metrika2clickhouse>
	</remote_servers>


	<!-- If element has 'incl' attribute, then for it's value will be used corresponding substitution from another file.
	By default, path to file with substitutions is /etc/metrika.xml. It could be changed in config in 'include_from' element.
	Values for substitutions are specified in /yandex/name_of_substitution elements in that file.
	-->

	<!-- ZooKeeper is used to store metadata about replicas, when using Replicated tables.
	Optional. If you don't use replicated tables, you could omit that.

	See https://clickhouse.yandex/reference_en.html#Data%20replication
	<zookeeper>
	<node index="1">
	<host>zookeeper</host>
	<port>2181</port>
	</node>
	</zookeeper>
	-->

	<!-- Substitutions for parameters of replicated tables.
	Optional. If you don't use replicated tables, you could omit that.

	See https://clickhouse.yandex/reference_en.html#Creating%20replicated%20tables
	-->
	<macros incl="macros" optional="true"/>


	<!-- Reloading interval for embedded dictionaries, in seconds. Default: 3600. -->
	<builtin_dictionaries_reload_interval>3600</builtin_dictionaries_reload_interval>


	<!-- Maximum session timeout, in seconds. Default: 3600. -->
	<max_session_timeout>3600</max_session_timeout>


	<!-- Default session timeout, in seconds. Default: 60. -->
	<default_session_timeout>60</default_session_timeout>

	<!-- Sending data to Graphite for monitoring. Several sections can be defined. -->
	<!--
	interval - send every X second
	root_path - prefix for keys
	metrics - send data from table system.metrics
	events - send data from table system.events
	asynchronous_metrics - send data from table system.asynchronous_metrics
	-->
	<use_graphite>false</use_graphite>
	<!--
	<graphite>
	<host>localhost</host>
	<port>42000</port>
	<timeout>0.1</timeout>
	<interval>60</interval>
	<root_path>one_min</root_path>

	<metrics>true</metrics>
	<events>true</events>
	<asynchronous_metrics>true</asynchronous_metrics>
	</graphite>
	<graphite>
	<host>localhost</host>
	<port>42000</port>
	<timeout>0.1</timeout>
	<interval>1</interval>
	<root_path>one_sec</root_path>

	<metrics>true</metrics>
	<events>true</events>
	<asynchronous_metrics>false</asynchronous_metrics>
	</graphite>
	-->

	<!-- Query log. Used only for queries with setting log_queries = 1. -->
	<query_log>
	<!-- What table to insert data. If table is not exist, it will be created.
	When query log structure is changed after system update,
	then old table will be renamed and new table will be created automatically.
	-->
	<database>system</database>
	<table>query_log</table>

	<!-- Interval of flushing data. -->
	<flush_interval_milliseconds>7500</flush_interval_milliseconds>
	</query_log>


	<!-- Uncomment if use part_log
	<part_log>
	<database>system</database>
	<table>part_log</table>

	<flush_interval_milliseconds>7500</flush_interval_milliseconds>
	</part_log>
	-->


	<!-- Parameters for embedded dictionaries, used in Yandex.Metrica.
	See https://clickhouse.yandex/reference_en.html#Internal%20dictionaries
	-->

	<!-- Path to file with region hierarchy. -->
	<!-- <path_to_regions_hierarchy_file>/opt/geo/regions_hierarchy.txt</path_to_regions_hierarchy_file> -->

	<!-- Path to directory with files containing names of regions -->
	<!-- <path_to_regions_names_files>/opt/geo/</path_to_regions_names_files> -->


	<!-- Configuration of external dictionaries. See:
	https://clickhouse.yandex/reference_en.html#External%20Dictionaries
	-->
	<dictionaries_config>*_dictionary.xml</dictionaries_config>


	<!-- Uncomment if you want data to be compressed 30-100% better.
	Don't do that if you just started using ClickHouse.
	-->
	<compression incl="clickhouse_compression">
	<!-- Set of variants. Checked in order. Last matching case wins. If nothing matches, lz4 will be used. -->
	<case>
	<!-- Conditions. All must be satisfied. Some conditions may be omitted. -->
	<min_part_size>10000000000</min_part_size> <!-- Min part size in bits. -->
	<min_part_size_ratio>0.01</min_part_size_ratio> <!-- Min size of part relative to whole table size. -->

	<!-- What compression method to use. -->
	<method>zstd</method> <!-- Keep in mind that zstd compression library is highly experimental. -->
	</case>
	</compression>

	<resharding>
	<task_queue_path>/clickhouse/task_queue</task_queue_path>
	</resharding>

	<!-- Allow to execute distributed DDL queries (CREATE, DROP, ALTER, RENAME) on cluster.
	Works only if ZooKeeper is enabled. Comment it if such functionality isn't required. -->
	<distributed_ddl>
	<!-- Path in ZooKeeper to queue with DDL queries -->
	<path>/clickhouse/task_queue/ddl</path>
	</distributed_ddl>

	<!-- Settings to fine tune MergeTree tables. See documentation in source code, in MergeTreeSettings.h -->
	<!--
	<merge_tree>
	<max_suspicious_broken_parts>5</max_suspicious_broken_parts>
	</merge_tree>
	-->

	<!-- Protection from accidental DROP.
	If size of a MergeTree table is greater than max_table_size_to_drop (in bytes) than table could not be dropped with any DROP query.
	If you want do delete one table and don't want to restart clickhouse-server, you could create special file <clickhouse-path>/flags/force_drop_table and make DROP once.
	By default max_table_size_to_drop is 50GB, max_table_size_to_drop=0 allows to DROP any tables.
	Uncomment to disable protection.
	-->
	<!-- <max_table_size_to_drop>0</max_table_size_to_drop> -->

	<!-- Example of parameters for GraphiteMergeTree table engine -->
	<graphite_rollup_example>
	<pattern>
	<regexp>click_cost</regexp>
	<function>any</function>
	<retention>
	<age>0</age>
	<precision>3600</precision>
	</retention>
	<retention>
	<age>86400</age>
	<precision>60</precision>
	</retention>
	</pattern>
	<default>
	<function>max</function>
	<retention>
	<age>0</age>
	<precision>60</precision>
	</retention>
	<retention>
	<age>3600</age>
	<precision>300</precision>
	</retention>
	<retention>
	<age>86400</age>
	<precision>3600</precision>
	</retention>
	</default>
	</graphite_rollup_example>
	</yandex>
	{"time":"2018-01-17T05:09:45Z","level":"debug","message":"tcp://localhost:9000/?username=&password=&block_size=0&debug=true"}
	[clickhouse]host(s)=localhost:9000, database=default, username=default
	[clickhouse][dial] secure=false, skip_verify=true, strategy=random, ident=1, server=0 -> 127.0.0.1:9000
	[clickhouse][connect=1][hello] -> Golang SQLDriver 1.1.54213
	[clickhouse][connect=1][hello] <- ClickHouse 1.1.54327 (Zulu)
	[clickhouse][connect=1]-> ping
	[clickhouse][connect=1][process] <- pong
	{"time":"2018-01-17T05:09:45Z","level":"debug","message":"InitClickhousePool Success with clickhousePool=map[localhost:9000:0xc42009e3c0] config.Clickhouse.Host
	s=[localhost:9000]"}
	[clickhouse][connect=1][prepare] SELECT now() AS nowDate
	[clickhouse][connect=1][send query] SELECT now() AS nowDate
	[clickhouse]host(s)=localhost:9000, database=default, username=default
	[clickhouse][connect=1][read meta] <- data: packet=1, columns=1, rows=0
	[clickhouse][dial] secure=false, skip_verify=true, strategy=random, ident=2, server=0 -> 127.0.0.1:9000
	[clickhouse][connect=1][rows] <- data: packet=1, columns=1, rows=1, elapsed=14.135чs
	[clickhouse][connect=1][rows] <- profiling: rows=1, bytes=12, blocks=1
	[clickhouse][connect=1][rows] <- progress: rows=1, bytes=1, total rows=0
	[clickhouse][connect=1][rows] <- data: packet=1, columns=0, rows=0, elapsed=10.058чs
	[clickhouse][connect=1][rows] <- end of stream
	{"time":"2018-01-17T05:09:45Z","level":"info","nowDate":"2018-01-17T05:09:45Z","message":"makeQuery OK"}
	[clickhouse][connect=1][rows] close
	[clickhouse][connect=1][stmt] close
	{"time":"2018-01-17T05:09:45Z","level":"info","message":"Pause 1 min"}
	[clickhouse][connect=2][hello] -> Golang SQLDriver 1.1.54213
	[clickhouse][connect=2][hello] <- ClickHouse 1.1.54327 (Zulu)
	[clickhouse][connect=2]-> ping
	[clickhouse][connect=2][process] <- pong
	[clickhouse][connect=1]-> ping
	[clickhouse][connect=1][process] <- pong
	[clickhouse][connect=2]-> ping
	[clickhouse][connect=2][process] <- pong
	[clickhouse][connect=1]-> ping
	[clickhouse][connect=1][process] <- pong
	[clickhouse][connect=2]-> ping
	[clickhouse][connect=2][process] <- pong
	[clickhouse][connect=1]-> ping
	[clickhouse][connect=1][process] <- pong
	[clickhouse][connect=2][prepare] SELECT now() AS nowDate
	[clickhouse][connect=2][send query] SELECT now() AS nowDate
	[clickhouse][connect=2][read meta] <- data: packet=1, columns=1, rows=0
	[clickhouse][connect=2][rows] <- data: packet=1, columns=1, rows=1, elapsed=32.319чs
	{"time":"2018-01-17T05:10:45Z","level":"info","nowDate":"2018-01-17T05:10:45Z","message":"makeQuery OK"}
	[clickhouse][connect=2][rows] <- profiling: rows=1, bytes=12, blocks=1
	[clickhouse][connect=2][rows] <- progress: rows=1, bytes=1, total rows=0
	[clickhouse][connect=2][rows] <- data: packet=1, columns=0, rows=0, elapsed=9.759чs
	[clickhouse][connect=2][rows] <- end of stream
	[clickhouse][connect=2][rows] close
	[clickhouse][connect=2][stmt] close
	{"time":"2018-01-17T05:10:45Z","level":"info","message":"Pause 1 min"}
	[clickhouse][connect=1]-> ping
	[clickhouse][connect=1][connect] write error: write tcp 127.0.0.1:36612->127.0.0.1:9000: i/o timeout
	{"time":"2018-01-17T05:10:45Z","level":"warn","clickhouseHost":"localhost:9000","error":"driver: bad connection","message":"some Clickhouse hosts is down"}
	{"time":"2018-01-17T05:10:45Z","level":"fatal","message":"All clickhouse hosts is Down"}
	exit status 1
	vagrant ssh
	ubuntu@local-bad-clickhouse-driver-clickhouse-pro:/home/ubuntu$ cd /vagrant
	ubuntu@local-bad-clickhouse-driver-clickhouse-pro:/vagrant$ export GOPATH=/home/ubuntu/go
	ubuntu@local-bad-clickhouse-driver-clickhouse-pro:/vagrant$ go get bad_ch_driver_close_connection.go
	ubuntu@local-bad-clickhouse-driver-clickhouse-pro:/vagrant$ go run bad_ch_driver_close_connection.go
	<?xml version="1.0"?>
	<yandex>
	<!-- Profiles of settings. -->
	<profiles>
	<!-- Default settings. -->
	<default>
	<!-- Maximum memory usage for processing single query, in bytes 2G. -->
	<max_memory_usage>2000000000</max_memory_usage>
	<max_memory_usage_for_user>2000000000</max_memory_usage_for_user>
	<max_memory_usage_for_all_queries>2000000000</max_memory_usage_for_all_queries>
	<background_pool_size>2</background_pool_size>
	<!--
	<min_insert_block_size_bytes>67108864</min_insert_block_size_bytes>
	<max_insert_block_size>524288</max_insert_block_size>
	<min_insert_block_size_rows>10000</min_insert_block_size_rows>
	-->

	<!-- Use cache of uncompressed blocks of data. Meaningful only for processing many of very short queries. -->
	<use_uncompressed_cache>1</use_uncompressed_cache>

	<!-- How to choose between replicas during distributed query processing.
	random - choose random replica from set of replicas with minimum number of errors
	nearest_hostname - from set of replicas with minimum number of errors, choose replica
	with minumum number of different symbols between replica's hostname and local hostname
	(Hamming distance).
	in_order - first live replica is choosen in specified order.
	-->
	<load_balancing>random</load_balancing>
	</default>

	<!-- Profile that allows only read queries. -->
	<readonly>
	<readonly>1</readonly>
	</readonly>
	</profiles>

	<!-- Users and ACL. -->
	<users>
	<!-- If user name was not specified, 'default' user is used. -->
	<default>
	<!-- Password could be specified in plaintext or in SHA256 (in hex format).

	If you want to specify password in plaintext (not recommended), place it in 'password' element.
	Example: <password>qwerty</password>.
	Password could be empty.

	If you want to specify SHA256, place it in 'password_sha256_hex' element.
	Example: <password_sha256_hex>65e84be33532fb784c48129675f9eff3a682b27168c0ea744b2cf58ee02337c5</password_sha256_hex>

	How to generate decent password:
	Execute: PASSWORD=$(base64 < /dev/urandom \| head -c8); echo "$PASSWORD"; echo -n "$PASSWORD" \| sha256sum \| tr -d '-'
	In first line will be password and in second - corresponding SHA256.
	-->
	<password></password>

	<!-- List of networks with open access.

	To open access from everywhere, specify:
	<ip>::/0</ip>

	To open access only from localhost, specify:
	<ip>::1</ip>
	<ip>127.0.0.1</ip>

	Each element of list has one of the following forms:
	<ip> IP-address or network mask. Examples: 213.180.204.3 or 10.0.0.1/8 or 2a02:6b8::3 or 2a02:6b8::3/64.
	<host> Hostname. Example: server01.yandex.ru.
	To check access, DNS query is performed, and all received addresses compared to peer address.
	<host_regexp> Regular expression for host names. Example, ^server\d\d-\d\d-\d\.yandex\.ru$
	To check access, DNS PTR query is performed for peer address and then regexp is applied.
	Then, for result of PTR query, another DNS query is performed and all received addresses compared to peer address.
	Strongly recommended that regexp is ends with $
	All results of DNS requests are cached till server restart.
	-->
	<networks incl="networks" replace="replace">
	<ip>::/0</ip>
	</networks>

	<!-- Settings profile for user. -->
	<profile>default</profile>

	<!-- Quota for user. -->
	<quota>default</quota>
	</default>

	<!-- Example of user with readonly access. -->
	<readonly>
	<password></password>
	<networks incl="networks" replace="replace">
	<ip>::1</ip>
	<ip>127.0.0.1</ip>
	</networks>
	<profile>readonly</profile>
	<quota>default</quota>
	</readonly>
	</users>

	<!-- Quotas. -->
	<quotas>
	<!-- Name of quota. -->
	<default>
	<!-- Limits for time interval. You could specify many intervals with different limits. -->
	<interval>
	<!-- Length of interval. -->
	<duration>3600</duration>

	<!-- No limits. Just calculate resource usage for time interval. -->
	<queries>0</queries>
	<errors>0</errors>
	<result_rows>0</result_rows>
	<read_rows>0</read_rows>
	<execution_time>0</execution_time>
	</interval>
	</default>
	</quotas>
	</yandex>
	# -- mode: ruby --
	# vi: set ft=ruby :
	Vagrant.configure(2) do \|config\|
	config.vm.box = "ubuntu/xenial64"
	config.vm.box_check_update = false

	config.hostmanager.enabled = true
	config.hostmanager.manage_host = true
	config.hostmanager.ignore_private_ip = false
	config.hostmanager.include_offline = false

	config.vm.provider "virtualbox" do \|vb\|
	vb.gui = false
	vb.memory = "1024"
	vb.customize ["setextradata", :id, "VBoxInternal2/SharedFoldersEnableSymlinksCreate/vagrant", "1"]
	end

	config.vm.define :bad_clickhouse_driver do \|bad_clickhouse_driver\|
	bad_clickhouse_driver.vm.synced_folder "./", "/home/ubuntu/go/src/gist.github.com/d56062af1332ff6322f74100dbcc8e63"
	bad_clickhouse_driver.vm.host_name = "local-bad-clickhouse-driver-clickhouse-pro"
	bad_clickhouse_driver.hostmanager.aliases = ["local.bad-clickhouse-driver.clickhouse.pro"]
	bad_clickhouse_driver.vm.network "private_network", ip: "172.16.2.77"
	bad_clickhouse_driver.vm.provision "shell", inline: <<-SHELL
	set -xeuo pipefail
	export DEBIAN_FRONTEND=noninteractive
	export GOPATH=/home/ubuntu/go
	apt-get update
	apt-get install -y apt-transport-https software-properties-common aptitude
	# clickhouse
	apt-key adv --keyserver keyserver.ubuntu.com --recv-keys E0C56BD4
	# gophers
	apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 136221EE520DDFAF0A905689B9316A7BC7917B12
	add-apt-repository "deb http://repo.yandex.ru/clickhouse/xenial/ stable main"
	add-apt-repository ppa:gophers/archive
	apt-get update
	apt-get install -y golang-1.9
	apt-get install -y clickhouse-server-common clickhouse-client
	cp -fv /vagrant/config.xml /etc/clickhouse-server/
	cp -fv /vagrant/users.xml /etc/clickhouse-server/
	ln -nvsf /usr/lib/go-1.9/bin/go /bin/go
	ln -nvsf /usr/lib/go-1.9/bin/gofmt /bin/gofmt
	systemctl restart clickhouse-server
	mkdir -p /home/ubuntu/go/bin
	bash -c "cd /home/ubuntu/go/src/gist.github.com/d56062af1332ff6322f74100dbcc8e63 && go get -v ./..."
	cd /vagrant && GOPATH=/home/ubuntu/go go run bad_ch_driver_close_connection.go
	set +x

	echo "bad_clickhouse_driver PROVISIONING DONE, use folloding scenario for reproduce bug"
	echo "# vagrant ssh bad_clickhouse_driver"
	echo "# sudo bash -c \\\"cd /vagrant && GOPATH=/home/ubuntu/go go run bad_ch_driver_close_connection.go \\\""
	echo "Good Luck ;)"
	SHELL
	end
	end