Node.js进程管理之Process模块

在前面Node.js事件运行机制也有提到,Node.js应用在单个线程运行,但是现在大部分服务器都是多处理器,为了方便使用多个进程,Node.js提供了3个模块。Process模块提供了访问正在运行的进程。child_process模块可以创建子进程，并与他们通信。cluster模块提供了实现共享相同端口的集群服务能力，允许多个请求同时处理。

一、Process模块是一个无须使用require()就可以从node.js应用程序进行访问的全局对象。

二、进程I/O管道

Process为进程stdin、stdout、stderr提供了对标准I/O管道的访问。(有点了类似C++的输入输出的赶脚)

stdin输入,stdout、stderr可以实现输出

/**
 * Created by Administrator on 2016/3/29.
 */
process.stdin.on('data',function(data){
    process.stdout.write(data.toString());
    process.stderr.write(data.toString());
});

"C:Program Files (x86)JetBrainsWebStorm 11.0.3in
unnerw.exe" F:
odejs
ode.exe Process.js
ssss
ssss
ssss

三、进程的信号

说起信号让我想起了信号量，虽然它们不是一回事，刚才也百度了下，算是复习重温一下。

我记得大学时候学操作系统的时候也有讲过信号量的问题，进程间通信访问临界值时要使用信号量什么PV操作,具体的内容了解的不是很清楚.网上找到了一个工作原理http://blog.csdn.net/ljianhui/article/details/10243617。

由于信号量只能进行两种操作等待和发送信号，即P(sv)和V(sv),他们的行为是这样的：

P(sv)：如果sv的值大于零，就给它减1；如果它的值为零，就挂起该进程的执行

V(sv)：如果有其他进程因等待sv而被挂起，就让它恢复运行，如果没有进程因等待sv而挂起，就给它加1.

两个进程共享信号量sv，一旦其中一个进程执行了P(sv)操作，它将得到信号量，并可以进入临界区，使sv减1。而第二个进程将被阻止进入临界区，因为当它试图执行P(sv)时，sv为0，它会被挂起以等待第一个进程离开临界区域并执行V(sv)释放信号量，这时第二个进程就可以恢复执行。

Node.js允许注册监听器来处理操作系统发送给一个进程的信号。可以被发送的node.js进程的事件有下面几个:

SIGUSR1 :启动调试器时发出。

SIGPIPE:进程试图写入在另一端没有进程连接的管道时发出

SIGHUP:Window上控制台关闭窗口时发出。在发出此事件约10秒会终止Node.js

SIGTERM:在发出一个终止进程的请求时发出.Windwo不支持。

SIGINT:当中断被发送到这个进程上,如Ctrl+C组合键被按下时发出

SIGBEAK:Windwo下Ctrl+Break组合键被按下时发出。

SIGWINCE:在控制台已经被调整大小时发出。Window下,只有当你写入控制台，移动光标或者在原始模式下使用可读的TTY时发出

SIGKILL:进程杀掉时发出

SIGSTOP:进程终止时发出。

监听的其实不止上面的信号在process的on定义中也能看出还有exit、uncaughtException等(可以转到定义)。

四、控制进程执行

abort():使当前的Node.js应用程序发出abort事件，退出,并产生一个内存核心转储文件

exit([code]):使当前Node.js应用退出，并返回指定的code

kill(pid,[signall]):操作系统会向指定的pid的进程发送一个kill信号，默认是SIGTERM

nexttick(callback):调度node.js程序的队列中的callback函数

五、从Process模块获取信息

var util = require('util');
//返回进程的当前工作目录
console.log('Current directory: ' + process.cwd());
//该进程的环境中指定的键/值对
console.log('Environment Settings: ' + JSON.stringify(process.env));
//用于启动Node.js应用程序的命令参数
console.log('Node Args: ' + process.argv);
//Node。js从中启动的绝对路径
console.log('Execution Path: ' + process.execPath);
//用于启动应用程序的特定节点的命令行选项
console.log('Execution Args: ' + JSON.stringify(process.execArgv));
//Node.js版本号
console.log('Node Version: ' + process.version);
//提供一个对象,包含Node.js应用程序所需的模块和版本
console.log('Module Versions: ' +  JSON.stringify(process.versions));
//用于编译当前节点可执行程序的配置选项
console.log('Node Config: ' +  JSON.stringify(process.config));
//当前进程ID
console.log('Process ID: ' + process.pid);
//当前进程标题
console.log('Process Title: ' + process.title);
//操作系统
console.log('Process Platform: ' + process.platform);
//进程正在运行的处理器体系结构
console.log('Process Architecture: ' + process.arch);
//Node.js进程的当前内存使用情况可使用util.inspect()读取
console.log('Memory Usage: ' + util.inspect(process.memoryUsage()));
//返回一个高精确的时间
var start = process.hrtime();
setTimeout(function() {
  var delta = process.hrtime(start);
  console.log('High-Res timer took %d seconds and %d nanoseconds', 
              delta[0], + delta[1]);
  console.log('Node has been running %d seconds', process.uptime());
}, 1000);

"C:Program Files (x86)JetBrainsWebStorm 11.0.3in
unnerw.exe" F:
odejs
ode.exe process_info.js
Current directory: c:UsersAdministratorDesktop
odejs-mongodb-angularjs-web-development-masterch09
Environment Settings: {"#envTSLOGTSLOG11328":"100839136","ALLUSERSPROFILE":"C:\ProgramData","APPDATA":"C:\Users\Administrator\AppData\Roaming","asl.log":"Destination=file","CommonProgramFiles":"C:\Program Files\Common Files","CommonProgramFiles(x86)":"C:\Program Files (x86)\Common Files","CommonProgramW6432":"C:\Program Files\Common Files","COMPUTERNAME":"LENOVO-PC","ComSpec":"C:\WINDOWS\system32\cmd.exe","configsetroot":"C:\WINDOWS\ConfigSetRoot","FPS_BROWSER_APP_PROFILE_STRING":"Internet Explorer","FPS_BROWSER_USER_PROFILE_STRING":"Default","FP_NO_HOST_CHECK":"NO","HOMEDRIVE":"C:","HOMEPATH":"\Users\Administrator","LOCALAPPDATA":"C:\Users\Administrator\AppData\Local","LOGONSERVER":"\\MicrosoftAccount","NUMBER_OF_PROCESSORS":"4","OS":"Windows_NT","Path":"C:\PROGRAM FILES (X86)\INTEL\ICLS CLIENT\;C:\PROGRAM FILES\INTEL\ICLS CLIENT\;C:\WINDOWS\SYSTEM32;C:\WINDOWS;C:\WINDOWS\SYSTEM32\WBEM;C:\WINDOWS\SYSTEM32\WINDOWSPOWERSHELL\V1.0\;C:\PROGRAM FILES\INTEL\INTEL(R) MANAGEMENT ENGINE COMPONENTS\DAL;C:\PROGRAM FILES\INTEL\INTEL(R) MANAGEMENT ENGINE COMPONENTS\IPT;C:\PROGRAM FILES (X86)\INTEL\INTEL(R) MANAGEMENT ENGINE COMPONENTS\DAL;C:\PROGRAM FILES (X86)\INTEL\INTEL(R) MANAGEMENT ENGINE COMPONENTS\IPT;C:\PROGRAM FILES (X86)\ATI TECHNOLOGIES\ATI.ACE\CORE-STATIC;;C:\WINDOWS\SYSTEM32;C:\WINDOWS;C:\WINDOWS\SYSTEM32\WBEM;C:\WINDOWS\SYSTEM32\WINDOWSPOWERSHELL\V1.0\;C:\PROGRAM FILES (X86)\AMD\ATI.ACE\CORE-STATIC;C:\Program Files\Lenovo\Bluetooth Software\;C:\Program Files\Lenovo\Bluetooth Software\syswow64;F:\nodejs\;C:\WINDOWS\system32\config\systemprofile\.dnx\bin;C:\Program Files\Microsoft DNX\Dnvm\;C:\Program Files (x86)\Lenovo\Lenovo Home\DCMainWin.exe;C:\Users\Administrator\AppData\Roaming\npm","PATHEXT":".COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC","PROCESSOR_ARCHITECTURE":"AMD64","PROCESSOR_IDENTIFIER":"Intel64 Family 6 Model 60 Stepping 3, GenuineIntel","PROCESSOR_LEVEL":"6","PROCESSOR_REVISION":"3c03","ProgramData":"C:\ProgramData","ProgramFiles":"C:\Program Files","ProgramFiles(x86)":"C:\Program Files (x86)","ProgramW6432":"C:\Program Files","PSModulePath":"C:\WINDOWS\system32\WindowsPowerShell\v1.0\Modules\","PUBLIC":"C:\Users\Public","SESSIONNAME":"Console","SystemDrive":"C:","SystemRoot":"C:\WINDOWS","TEMP":"C:\Users\ADMINI~1\AppData\Local\Temp","TMP":"C:\Users\ADMINI~1\AppData\Local\Temp","USERDOMAIN":"LENOVO-PC","USERDOMAIN_ROAMINGPROFILE":"LENOVO-PC","USERNAME":"Administrator","USERPROFILE":"C:\Users\Administrator","VS140COMNTOOLS":"C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\Tools\","windir":"C:\WINDOWS"}
Node Args: F:
odejs
ode.exe,c:UsersAdministratorDesktop
odejs-mongodb-angularjs-web-development-masterch09process_info.js
Execution Path: F:
odejs
ode.exe
Execution Args: []
Node Version: v4.3.2
Module Versions: {"http_parser":"2.5.2","node":"4.3.2","v8":"4.5.103.35","uv":"1.8.0","zlib":"1.2.8","ares":"1.10.1-DEV","icu":"56.1","modules":"46","openssl":"1.0.2g"}
Node Config: {"target_defaults":{"cflags":[],"default_configuration":"Release","defines":[],"include_dirs":[],"libraries":[]},"variables":{"asan":0,"host_arch":"x64","icu_data_file":"icudt56l.dat","icu_data_in":"../../deps/icu/source/data/in\icudt56l.dat","icu_endianness":"l","icu_gyp_path":"tools/icu/icu-generic.gyp","icu_locales":"en,root","icu_path":"deps\icu","icu_small":true,"icu_ver_major":"56","node_byteorder":"little","node_install_npm":true,"node_prefix":"/usr/local","node_release_urlbase":"","node_shared_http_parser":false,"node_shared_libuv":false,"node_shared_openssl":false,"node_shared_zlib":false,"node_tag":"","node_use_dtrace":false,"node_use_etw":true,"node_use_lttng":false,"node_use_openssl":true,"node_use_perfctr":true,"openssl_fips":"","openssl_no_asm":0,"python":"C:\Python27\python.exe","target_arch":"x64","v8_enable_gdbjit":0,"v8_enable_i18n_support":1,"v8_no_strict_aliasing":1,"v8_optimized_debug":0,"v8_random_seed":0,"v8_use_snapshot":true,"want_separate_host_toolset":0}}
Process ID: 8124
Process Title: C:Program Files (x86)JetBrainsWebStorm 11.0.3in
unnerw.exe
Process Platform: win32
Process Architecture: x64
Memory Usage: { rss: 17641472, heapTotal: 7409232, heapUsed: 3756584 }
High-Res timer took 1 seconds and 107153 nanoseconds
Node has been running 1.128 seconds

Process finished with exit code 0