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Commit f69a71e

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‎README.md

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@@ -53,11 +53,11 @@ ps:白天上班,晚上更新,尽量日更,比心
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[第19章 依赖管理](https://github.com/java-aodeng/golang-examples/blob/master/src/go-19/module_package/get_remote_pack_test.go)
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> 并发编程,学go的目的开始了,前面都是基础
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> 并发编程
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[第20章 协程机制](https://github.com/java-aodeng/golang-examples/blob/master/go-20/groutine_test.go)
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第21章 共享内存并发机制
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[第21章 共享内存并发机制](https://github.com/java-aodeng/golang-examples/blob/master/go-21/share_mem_test.go)
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第22章 CSP并发机制
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‎go-21/share_mem_test.go

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package go_21
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import (
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"sync"
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"testing"
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"time"
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)
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/*
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共享内存并发机制 就类似于java里面的锁
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都是些很简单的东西,直接看代码
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*/
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//不加锁的情况
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func TestCounter(t *testing.T) {
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count := 0
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for i := 0; i < 5000; i++ {
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go func() {
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count++
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}()
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}
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time.Sleep(1 * time.Second)
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t.Logf("count=%d", count)
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}
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//运行结果 结果不是我们预想中的5000,发生了写入的问题,不是线程安全的
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//=== RUN TestCounter
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//--- PASS: TestCounter (1.02s)
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//share_mem_test.go:22: count=4936
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//PASS
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//加锁的情况
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func TestCounterThreadSafe(t *testing.T) {
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var mut = sync.Mutex{}
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count := 0
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for i := 0; i < 5000; i++ {
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go func() {
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defer func() {
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mut.Unlock()
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}()
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mut.Lock()
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count++
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}()
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}
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time.Sleep(1 * time.Second)
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t.Logf("count=%d", count)
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}
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//运行结果 加锁之后结果是预想中的
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//=== RUN TestCounterThreadSafe
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//--- PASS: TestCounterThreadSafe (1.02s)
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//share_mem_test.go:47: count=5000
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//PASS
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//线程等待
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func TestCounterWaitGroup(t *testing.T) {
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var mut sync.Mutex
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var wg sync.WaitGroup
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count := 0
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for i := 0; i < 5000; i++ {
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wg.Add(1)
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go func() {
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defer func() {
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mut.Unlock()
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}()
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mut.Lock()
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count++
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wg.Done()
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}()
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}
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wg.Wait()
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t.Logf("count=%d", count)
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}
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//运行结果
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//=== RUN TestCounterWaitGroup
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//--- PASS: TestCounterWaitGroup (0.03s)
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//share_mem_test.go:73: count=5000
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//PASS

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