kevinclcn

Go vs. Scala (Akka) Concurrency

A comparison from 2 weeks using Go.

Actors vs. Functions

Akka's central principle is that there you have an ActorSystem which runs Actors. An Actor is defined as a class and it has a method to receive messages.

kevinclcn

/*
 * Main.java
 *
 * Created on 27 August 2007, 11:11
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */

package hotthread;

kevinclcn

# script used in consul to check if mysql is primary master and asynchronous slave
# v.0.1 - lefred 2018-02-16

SLAVEOFDC="dc2"
SLAVEUSER="async_repl"
SLAVEPWD="asyncpwd"

# check if we are the primary one
ROLE=$(mysql -h 127.0.0.1 -BNe "select MEMBER_ROLE from performance_schema.replication_group_members where MEMBER_HOST=@@hostname")

kevinclcn

# script used in consul
# the following addition to sys is required: 
#   https://gist.github.com/lefred/153448f7ea0341d6d0daa2738db6fcd8
# v.0.1 - lefred 2018-02-14


read -r mysql_primary mysql_readonly mysql_tx mysql_cert <<<$(mysql -h 127.0.0.1 -P 6446 -BNe "select * from sys.gr_member_routing_candidate_status")

if [[ "${mysql_primary}" == "YES" ]] && [[ "${mysql_readonly}" == "NO" ]]
then

kevinclcn

package main

import (
	"fmt"
	"sync"
)

type Fetcher interface {
	// Fetch returns the body of URL and
	// a slice of URLs found on that page.

kevinclcn

http://code.haleby.se/2017/01/27/markdown-to-pdf-in-macosx/

• 安装pandoc，mactex和xelatex
• 命令行程序都在/Libarary/Tex/Root/bin/x86_64-darwin/下面，需要将pdflatex, xelatex, tlmgr链接到/user/local/bin下面
• 需要使用tlmgr安装titling, lastpage
• 需要提供一个导出pdf的latex模板，默认的模板不支持中文
• 调用命令生成pdf

pandoc --pdf-engine=xelatex --template=template accesstoken.md create.md customer.md customerevent.md list.md tag.md -o customer.pdf

kevinclcn

# from http://dzone.com/snippets/analyse-binary-log

# cat /bin/mylog
#!/bin/sh
# usage:
#$ mylog /mysql-bin-log/db-bin.000223
#   2132 insert into customers
#   1887 update userlog_access
#    788 insert into gn_commission
#    718 insert into con_tab 

kevinclcn

BenchmarkMutexCache/10-8            10000000	       180 ns/op	       0 B/op	       0 allocs/op
BenchmarkMutexCache/100-8           10000000	       187 ns/op	       0 B/op	       0 allocs/op
BenchmarkMutexCache/1000-8          10000000	       214 ns/op	       0 B/op	       0 allocs/op
BenchmarkMutexCache/10000-8         10000000	       231 ns/op	       0 B/op	       0 allocs/op
BenchmarkMutexCache/100000-8         5000000	       254 ns/op	       2 B/op	       0 allocs/op
BenchmarkMutexCache/1000000-8        1000000	      1159 ns/op	     102 B/op	       1 allocs/op
BenchmarkMutexCache/10000000-8       1000000	      1481 ns/op	     184 B/op	       2 allocs/op
BenchmarkMutexCache/100000000-8      1000000	      1655 ns/op	     187 B/op	       3 allocs/op

BenchmarkSyncMapCache/10-8           5000000	       221 ns/op	       0 B/op	       0 allocs/op

kevinclcn

Docker - How to cleanup (unused) resources

Once in a while, you may need to cleanup resources (containers, volumes, images, networks) ...

delete volumes

// see: https://github.com/chadoe/docker-cleanup-volumes

$ docker volume rm $(docker volume ls -qf dangling=true)

$ docker volume ls -qf dangling=true | xargs -r docker volume rm

kevinclcn

package main

import (
        "fmt"
        "log"
        "net"
        "time"
)

// Dialer .