LeCoupa

# Redis Cheatsheet
# All the commands you need to know


redis-server /path/redis.conf  # start redis with the related configuration file
redis-cli                      # opens a redis prompt


# Strings.

ursuad

Kafka Topics

List existing topics

bin/kafka-topics.sh --zookeeper localhost:2181 --list

Describe a topic

bin/kafka-topics.sh --zookeeper localhost:2181 --describe --topic mytopic

Purge a topic

bin/kafka-topics.sh --zookeeper localhost:2181 --alter --topic mytopic --config retention.ms=1000

... wait a minute ...

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

billywhizz

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <pthread.h>
#include <sys/time.h>

#define P 2

static uint64_t volatile counter = 0;
pthread_mutex_t mutex;