djspiewak

Getting Started in Scala

This is my attempt to give Scala newcomers a quick-and-easy rundown to the prerequisite steps they need to a) try Scala, and b) get a standard project up and running on their machine. I'm not going to talk about the language at all; there are plenty of better resources a google search away. This is just focused on the prerequisite tooling and machine setup. I will not be assuming you have any background in JVM languages. So if you're coming from Python, Ruby, JavaScript, Haskell, or anywhere…  I hope to present the information you need without assuming anything.

Disclaimer It has been over a decade since I was new to Scala, and when I was new to Scala, I was coming from a Java and Ruby background. This has probably caused me to unknowingly make some assumptions. Please feel free to call me out in comments/tweets!

One assumption I'm knowingly making is that you're on a Unix-like platform. Sorry, Windows users.

Getting the JVM

mgoodness

AWS Service annotations

• service.beta.kubernetes.io/aws-load-balancer-access-log-emit-interval (in minutes)
• service.beta.kubernetes.io/aws-load-balancer-access-log-enabled (true|false)
• service.beta.kubernetes.io/aws-load-balancer-access-log-s3-bucket-name
• service.beta.kubernetes.io/aws-load-balancer-access-log-s3-bucket-prefix
• service.beta.kubernetes.io/aws-load-balancer-additional-resource-tags (comma-separated list of key=value)
• service.beta.kubernetes.io/aws-load-balancer-backend-protocol (http|https|ssl|tcp)
• service.beta.kubernetes.io/aws-load-balancer-connection-draining-enabled (true|false)

ipbastola

Safest way to clean up boot partition - Ubuntu 14.04LTS-x64, Ubuntu 16.04LTS-x64

Reference

Case I: if /boot is not 100% full and apt is working

1. Check the current kernel version

$ uname -r 

skroah

##Reactive System Design Links

#Articles and Papers

• The Reactive Manifesto: http://www.reactivemanifesto.org/
• https://en.wikipedia.org/wiki/Reactive_programming
• https://en.wikipedia.org/wiki/Functional_reactive_programming
• Design Methods for Reactive Systems book slides: http://booksite.elsevier.com/9781558607552/slides/slides.pdf
• Programming without a callstack Event Driven Architectures By G Hohpe: http://www.eaipatterns.com/docs/EDA.pdf
• On Distributed Memory Systems: http://blog.paralleluniverse.co/2012/07/10/on-distributed-memory/
• Disruptor source code, papers and articles: https://lmax-exchange.github.io/disruptor/

danneu

My efforts to port http://www.youtube.com/watch?v=f6kdp27TYZs to Clojure.

A boring function (6:22)

func boring(msg string) {
  for i := 0; ; i++ {
    fmt.Println(msg, i)
    time.Sleep(time.Second)
 }

jamesmacaulay

{:user {:dependencies [[org.clojure/tools.namespace "0.2.3"]
                       [spyscope "0.1.3"]
                       [criterium "0.4.1"]]
        :injections [(require '(clojure.tools.namespace repl find))
                     ; try/catch to workaround an issue where `lein repl` outside a project dir
                     ; will not load reader literal definitions correctly:
                     (try (require 'spyscope.core)
                       (catch RuntimeException e))]
        :plugins [[lein-pprint "1.1.1"]
                  [lein-beanstalk "0.2.6"]

jamesmacaulay

// installed Clojure packages:
// 
// * BracketHighlighter
// * lispindent
// * SublimeREPL
// * sublime-paredit

{
  "word_separators": "/\\()\"',;!@$%^&|+=[]{}`~?",
  "paredit_enabled": true,

mmdemirbas

DECLARE E INT DEFAULT 0;
DECLARE M TEXT DEFAULT NULL;
	
DECLARE CONTINUE HANDLER FOR 1000 SET E='1000', M="hashchk";
DECLARE CONTINUE HANDLER FOR 1001 SET E='1001', M="isamchk";
DECLARE CONTINUE HANDLER FOR 1002 SET E='1002', M="NO";
DECLARE CONTINUE HANDLER FOR 1003 SET E='1003', M="YES";
DECLARE CONTINUE HANDLER FOR 1004 SET E='1004', M="Can't create file '%s' (errno: %d)";
DECLARE CONTINUE HANDLER FOR 1005 SET E='1005', M="Can't create table '%s' (errno: %d)";
DECLARE CONTINUE HANDLER FOR 1006 SET E='1006', M="Can't create database '%s' (errno: %d)";

jboner

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

duydo

If you want, I can try and help with pointers as to how to improve the indexing speed you get. Its quite easy to really increase it by using some simple guidelines, for example:

- Use create in the index API (assuming you can).
- Relax the real time aspect from 1 second to something a bit higher (index.engine.robin.refresh_interval).
- Increase the indexing buffer size (indices.memory.index_buffer_size), it defaults to the value 10% which is 10% of the heap.
- Increase the number of dirty operations that trigger automatic flush (so the translog won't get really big, even though its FS based) by setting index.translog.flush_threshold (defaults to 5000).
- Increase the memory allocated to elasticsearch node. By default its 1g.
- Start with a lower replica count (even 0), and then once the bulk loading is done, increate it to the value you want it to be using the update_settings API. This will improve things as possibly less shards will be allocated to each machine.
- Increase the number of machines you have so