# mit6.824

**Repository Path**: wxx213/mit6.824

## Basic Information

- **Project Name**: mit6.824
- **Description**: No description available
- **Primary Language**: Go
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2021-06-21
- **Last Updated**: 2023-02-02

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# 介绍

[mit6.824](http://nil.csail.mit.edu/6.824/2020/schedule.html) 课程的Lab代码

原始的代码仓库地址

```
git://g.csail.mit.edu/6.824-golabs-2020
```

# Raft

网页地址：http://nil.csail.mit.edu/6.824/2020/labs/lab-raft.html

## 基本概念

### 日志复制

日志提交(commit)：for follower, 日志已经被保存到了本地日志序列；for leader, 日志已经被大部分节点复制

日志应用(apply)：日志（作为元数据）已经被应用到了本地状态机（本地存储系统）

## 调试

### 日志打印

设置日志可以显示行号和毫秒时间戳

```go
log.SetFlags(log.Lshortfile | log.LstdFlags | log.Lmicroseconds)
```

打印节点角色信息

```go
func stack() string {
	var buf [2 << 10]byte
	return string(buf[:runtime.Stack(buf[:], false)])
}

// for debug, print node role
func checkrole(cfg *config) {
	var term int
	var isleader bool

	log.Println("start checkrole")
	fmt.Println("server term isleader electiontimeoutms role connected logindex commitindex applylogs nextIndex")
	for i:=0;i<cfg.n;i++ {
		term, isleader = cfg.rafts[i].GetState()
		fmt.Println(i,"    ",term,"  ",isleader,"   ",cfg.rafts[i].electiontimeoutms,
			"             ",cfg.rafts[i].roleState,"    ", cfg.connected[i],
			"    ",cfg.rafts[i].logIndex, "", cfg.rafts[i].commitIndex, "    ", len(cfg.logs[i]), "    ", cfg.rafts[i].nextIndex)
	}
	log.Println("stack: ", stack())
}
```

### panic调试

1. 配置core文件大小

   ```
   ulimit -c unlimited
   ```

2. 设置golang程序在panic时生成core，添加环境变量

   ```
   GOTRACEBACK=crash
   ```

3. 修改go test执行方法

   ```shell
   # 只编译不执行，生成可执行文件raft.test
   go test -c
   # 执行特定的测试
   ./raft.test -test.run $test
   ```

   ​