next article (§12) for details. return lines in function declarations. deferred function calls and goroutine creations. The two will be introduced in the article after next (§13). Examples of Expressions Function Calls and Panic/Recover This article will introduce goroutines and deferred function calls. Goroutine and deferred function call are two unique features in Go. This article also explains panic and recover program, a computer, or a network. In Go 101, we only talk about program-scope concurrent computing. Goroutine is the Go way to create concurrent computations in Go programming. Goroutines are also often called

article (§12) for details. return lines in function declarations. deferred function calls and goroutine creations. The two will be introduced in the article after next (§13). Examples of Expressions Function Calls and Panic/Recover This article will introduce goroutines and deferred function calls. Goroutine and deferred function call are two unique features in Go. This article also explains panic and recover program, a computer, or a network. In Go 101, we only talk about program-scope concurrent computing. Goroutine is the Go way to create concurrent computations in Go programming. Goroutines are also often called

article (§12) for details. return lines in function declarations. deferred function calls and goroutine creations. The two will be introduced in the article after next (§13). Examples of Expressions Function Calls and Panic/Recover This article will introduce goroutines and deferred function calls. Goroutine and deferred function call are two unique features in Go. This article also explains panic and recover program, a computer, or a network. In Go 101, we only talk about program-scope concurrent computing. Goroutine is the Go way to create concurrent computations in Go programming. Goroutines are also often called

14.2.5 Asynchronous channels—making a channel with a buffer ........................387 14.2.6 Goroutine using a channel for outputting result(s) ...................................388 14.2.7 Semaphore init() function is also frequently used when (for example for a server application) a backend() goroutine is required from the start of the application, like in: func init() { // setup preparations possibilities. There is also a function time.Sleep(Duration d), which pauses the current process (goroutine in fact, see § 14.1) for a Duration d. 4.9. Pointers Unlike Java and .NET, Go gives the programmer

Usage By Tag CPU Usage By Tag Another approach to CPU resource bind in Go Goroutine CPU Stats ● Try to collect goroutine runtime information. begin := GetGoroutineStats()
 
 executeSQL()
 
 end := ebug/pprof/trace\?seconds\=1 --output trace.out go tool trace trace.out ● In Goroutine analysis Page, chose the Goroutine you want to view. Trace - drawback ● Large performance impact. ● May generate Event goroutine_id description 0 GoCreate 1 创建⼀个 goroutine 10 GoStart 1 开始运⾏ goroutine 30 GoBlockSelect 1 被 block 了，暂停运⾏ goroutine 50 GoUnpark 1 goroutine 没有被 block 了 60 GoStart 1 开始运⾏ goroutine 80

那也⼀定要有能通过配置开启的能⼒ CPU ⽤爆了？90%？ 内存⽤爆了？OOM? Goroutine ⽤爆了？80w? 线程数爆了？ 延迟太⾼？ 压测时关注哪些服务指标 压测时关注哪些服务指标 因为我们是 Go 的服务，还可以额外看看： • Goroutine 数，线程数 • 如果 Goroutine 数很多，那这些 Goroutine 在⼲什么？ • GC 频率，gctrace 的内容(线上保存 gctrace -> 看 prometheus，内存 RSS 是多少，goroutine 数量多少，goroutine 栈占⽤多少 -> 如果 goroutine 不多，那么重 点关注 heap profile 中的 inuse -> 定时任务类需要看 alloc 4. goroutine 数量过多 -> 从 profile ⽹⻚进去看看 goroutine 都在⼲什 么 -> 查死锁、阻塞等问题 -> 个别不在意延迟的选择第三⽅库优 com/golang/go/pull/42036#issuecomment-715046540 怎么样说服官⽅接受性能优化的 PR 内存占⽤过⾼-goroutine 数量太多导致内存占⽤⾼ 这些内存的构成部分： 1. Goroutine 栈占⽤的内存(难优化，⼀条 tcp 连接⾄少对应⼀个 goroutine) 2. Tcp read buffer 占⽤的内存(难优化，因为⼤部分连接阻塞在 read 上， read buffer

空interface interface函数参数 interface变量存储的类型 嵌入interface 反射 并发 goroutine channels Buffered Channels Range和Close Select 超时 runtime goroutine 错误处理 Error类型 自定义Error 错误处理 总结 更多Golang资源包：https://github 的行为就 像调用了 panic 。这一过程继续向上，直到发生 panic 的 goroutine 中所有调用的函数返回，此时程 序退出。 panic 可以直接调用 panic 产生。也可以由运行时错误产生，例如访问越界的数组。 Recover 是一个内建的函数，可以让进入 panic 状态的 goroutine 恢复过来。 recover 仅在延迟函数中有效。 在正常的执行过程中，调用 recover recover 会返回 nil ，并且没有其它任何效果。如果当前的 goroutine 陷 入 panic 状态，调用 recover 可以捕获到 panic 的输入值，并且恢复正常的执行。 下面这个函数演示了如何在过程中使用 panic 下面这个函数检查作为其参数的函数在执行时是否会产生 panic ： return true } return false

过程继续向上，直到发生panic的goroutine中所有调用的函数返回，此时程序退出。恐慌可以直接调用panic产 生。也可以由运行时错误产生，例如访问越界的数组。 Recover 是一个内建的函数，可以让进入令人恐慌的流程中的goroutine恢复过来。recover仅在延迟函数中有效。在正常 的执行过程中，调用recover会返回nil，并且没有其它任何效果。如果当前的goroutine陷入恐慌，调用 要的就是并行程序设计，而GO从语言 层面就支持了并行。 goroutine goroutine goroutine是Go并行设计的核心。goroutine说到底其实就是线程，但是他比线程更小，十几个goroutine可能体现在 底层就是五六个线程，Go语言内部帮你实现了这些goroutine之间的内存共享。执行goroutine只需极少的栈内存(大 概是4~5KB)，当然会根据相应的数据伸 缩。也正因为如此，可同时运行成千上万个并发任务。goroutine比thread更 易用、更高效、更轻便。 goroutine是通过Go的runtime管理的一个线程管理器。goroutine通过go关键字实现了，其实就是一个普通的函数。 go hello(a, b, c) 通过关键字go就启动了一个goroutine。我们来看一个例子 package main import (

will not terminate until all of these functions return with panic to the first level of that goroutine . panic can be produced by calling panic in the program, and some errors also cause panic like array access out of bounds errors. Recover is a built-in function to recover goroutine s from panic status. Calling recover in defer functions is useful because normal functions will not concurrency is a hot topic in today's world, and Go supports this feature at the language level. goroutine goroutines and concurrency are built into the core design of Go. They're similar to threads but

启动外部命令和程序 13.7 Go 中的单元测试和基准测试 13.8 测试的具体例子 13.9 用（测试数据）表驱动测试 13.10 性能调试：分析并优化 Go 程序 第 14 章 协程（goroutine）与通道（channel） 14.1 什么是协程 14.2 协程间的信道 14.3 协程的同步：关闭通道-测试阻塞的通道 14.4 使用 select 切换协程 14.5 通道、超时和计时器（Ticker） 18章 出于性能考虑的实用代码片段 18.1 字符串 18.2 数组和切片 18.3 映射 18.4 结构体 18.5 接口 18.6 函数 18.7 文件 18.8 协程（goroutine）与通道（channel） 18.9 网络和网页应用 18.10 其他 18.11 出于性能考虑的最佳实践和建议 - 6 - 本文档使用 书栈(BookStack.CN) 构建 致谢 式来进行软件开发。它并不是要用奇怪的语法和晦涩难懂的概念 来从根本上推翻已有的编程语言，而是建立并改善了 C、Java、C# 中的许多语法风格。它提倡通过接口来针对面向 对象编程，通过 goroutine 和 channel 来支持并发和并行编程。 这本书是为那些想要学习 Go 这门全新的，迷人的和充满希望的编程语言的开发者量身定做的。当然，你在学习 Go 语言之前需要具备一些关于编程的基