Nginx源码分析 - 主流程篇 - 多进程实现（14）

一、Nginx多进程实现的流程图

二、Nginx多进程具体实现

1. ngx_master_process_cycle 进入多进程模式

2. ngx_start_worker_processes 创建工作进程

3. ngx_spawn_process fork工作进程

4. ngx_worker_process_cycle 子进程的回调函数

5. ngx_worker_process_init 工作进程初始化

默认情况下，Nginx都是多进程的运行模式。Nginx和Memcached不一样，是多进程的模式。采用多进程模式最大的好处：

每个进程的资源独立
不需要添加各种繁琐的锁了

一、Nginx多进程实现的流程图

二、Nginx多进程具体实现

1. ngx_master_process_cycle 进入多进程模式

ngx_master_process_cycle方法主要做了两个工作：

主进程进行信号的监听和处理
开启子进程

void  ngx_master_process_cycle(ngx_cycle_t *cycle)
{char              *title;u_char            *p;size_t             size;ngx_int_t          i;ngx_uint_t         n, sigio;sigset_t           set;struct itimerval   itv;ngx_uint_t         live;ngx_msec_t         delay;ngx_listening_t   *ls;ngx_core_conf_t   *ccf;sigemptyset(&set);sigaddset(&set, SIGCHLD);sigaddset(&set, SIGALRM);sigaddset(&set, SIGIO);sigaddset(&set, SIGINT);sigaddset(&set, ngx_signal_value(NGX_RECONFIGURE_SIGNAL));sigaddset(&set, ngx_signal_value(NGX_REOPEN_SIGNAL));sigaddset(&set, ngx_signal_value(NGX_NOACCEPT_SIGNAL));sigaddset(&set, ngx_signal_value(NGX_TERMINATE_SIGNAL));sigaddset(&set, ngx_signal_value(NGX_SHUTDOWN_SIGNAL));sigaddset(&set, ngx_signal_value(NGX_CHANGEBIN_SIGNAL));if (sigprocmask(SIG_BLOCK, &set, NULL) == -1) {ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,"sigprocmask() failed");}sigemptyset(&set);size = sizeof(master_process);for (i = 0; i < ngx_argc; i++) {size += ngx_strlen(ngx_argv[i]) + 1;}title = ngx_pnalloc(cycle->pool, size);if (title == NULL) {/* fatal */exit(2);}p = ngx_cpymem(title, master_process, sizeof(master_process) - 1);for (i = 0; i < ngx_argc; i++) {*p++ = ' ';p = ngx_cpystrn(p, (u_char *) ngx_argv[i], size);}ngx_setproctitle(title);// 从配置文件中获取ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);// 进程的创建就是在这个地方ngx_start_worker_processes(cycle, ccf->worker_processes,NGX_PROCESS_RESPAWN);ngx_start_cache_manager_processes(cycle, 0);ngx_new_binary = 0;delay = 0;sigio = 0;live = 1;for ( ;; ) {if (delay) {if (ngx_sigalrm) {sigio = 0;delay *= 2;ngx_sigalrm = 0;}ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,"termination cycle: %M", delay);itv.it_interval.tv_sec = 0;itv.it_interval.tv_usec = 0;itv.it_value.tv_sec = delay / 1000;itv.it_value.tv_usec = (delay % 1000 ) * 1000;if (setitimer(ITIMER_REAL, &itv, NULL) == -1) {ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,"setitimer() failed");}}ngx_log_debug0(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "sigsuspend");sigsuspend(&set);ngx_time_update();ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,"wake up, sigio %i", sigio);if (ngx_reap) {ngx_reap = 0;ngx_log_debug0(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "reap children");live = ngx_reap_children(cycle);}if (!live && (ngx_terminate || ngx_quit)) {ngx_master_process_exit(cycle);}if (ngx_terminate) {if (delay == 0) {delay = 50;}if (sigio) {sigio--;continue;}sigio = ccf->worker_processes + 2 /* cache processes */;if (delay > 1000) {ngx_signal_worker_processes(cycle, SIGKILL);} else {ngx_signal_worker_processes(cycle,ngx_signal_value(NGX_TERMINATE_SIGNAL));}continue;}if (ngx_quit) {ngx_signal_worker_processes(cycle,ngx_signal_value(NGX_SHUTDOWN_SIGNAL));ls = cycle->listening.elts;for (n = 0; n < cycle->listening.nelts; n++) {if (ngx_close_socket(ls[n].fd) == -1) {ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_socket_errno,ngx_close_socket_n " %V failed",&ls[n].addr_text);}}cycle->listening.nelts = 0;continue;}if (ngx_reconfigure) {ngx_reconfigure = 0;if (ngx_new_binary) {ngx_start_worker_processes(cycle, ccf->worker_processes,NGX_PROCESS_RESPAWN);ngx_start_cache_manager_processes(cycle, 0);ngx_noaccepting = 0;continue;}ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "reconfiguring");cycle = ngx_init_cycle(cycle);if (cycle == NULL) {cycle = (ngx_cycle_t *) ngx_cycle;continue;}ngx_cycle = cycle;ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx,ngx_core_module);ngx_start_worker_processes(cycle, ccf->worker_processes,NGX_PROCESS_JUST_RESPAWN);ngx_start_cache_manager_processes(cycle, 1);/* allow new processes to start */ngx_msleep(100);live = 1;ngx_signal_worker_processes(cycle,ngx_signal_value(NGX_SHUTDOWN_SIGNAL));}if (ngx_restart) {ngx_restart = 0;ngx_start_worker_processes(cycle, ccf->worker_processes,NGX_PROCESS_RESPAWN);ngx_start_cache_manager_processes(cycle, 0);live = 1;}if (ngx_reopen) {ngx_reopen = 0;ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "reopening logs");ngx_reopen_files(cycle, ccf->user);ngx_signal_worker_processes(cycle,ngx_signal_value(NGX_REOPEN_SIGNAL));}if (ngx_change_binary) {ngx_change_binary = 0;ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "changing binary");ngx_new_binary = ngx_exec_new_binary(cycle, ngx_argv);}if (ngx_noaccept) {ngx_noaccept = 0;ngx_noaccepting = 1;ngx_signal_worker_processes(cycle,ngx_signal_value(NGX_SHUTDOWN_SIGNAL));}}
}

2. ngx_start_worker_processes 创建工作进程

通过循环创建N个子进程。每个子进程都有独立的内存空间。
子进程的个数由Nginx的配置：ccf->worker_processes决定


//启动进程的地方
static void ngx_start_worker_processes(ngx_cycle_t *cycle, ngx_int_t n, ngx_int_t type)
{ngx_int_t      i;ngx_channel_t  ch;ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "start worker processes");ngx_memzero(&ch, sizeof(ngx_channel_t));ch.command = NGX_CMD_OPEN_CHANNEL;for (i = 0; i < n; i++) {// 每个子进程执行的地方ngx_spawn_process(cycle, ngx_worker_process_cycle,(void *) (intptr_t) i, "worker process", type);ch.pid = ngx_processes[ngx_process_slot].pid;ch.slot = ngx_process_slot;ch.fd = ngx_processes[ngx_process_slot].channel[0];ngx_pass_open_channel(cycle, &ch);}
}

3. ngx_spawn_process fork工作进程

ngx_spawn_process方法主要用于fork出各个工作进程。具体主要看fork过程的代码。


ngx_pid_t
ngx_spawn_process(ngx_cycle_t *cycle, ngx_spawn_proc_pt proc, void *data,char *name, ngx_int_t respawn)
{u_long     on;ngx_pid_t  pid;ngx_int_t  s;if (respawn >= 0) {s = respawn;} else {for (s = 0; s < ngx_last_process; s++) {if (ngx_processes[s].pid == -1) {break;}}if (s == NGX_MAX_PROCESSES) {ngx_log_error(NGX_LOG_ALERT, cycle->log, 0,"no more than %d processes can be spawned",NGX_MAX_PROCESSES);return NGX_INVALID_PID;}}if (respawn != NGX_PROCESS_DETACHED) {/* Solaris 9 still has no AF_LOCAL */if (socketpair(AF_UNIX, SOCK_STREAM, 0, ngx_processes[s].channel) == -1){ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,"socketpair() failed while spawning \"%s\"", name);return NGX_INVALID_PID;}ngx_log_debug2(NGX_LOG_DEBUG_CORE, cycle->log, 0,"channel %d:%d",ngx_processes[s].channel[0],ngx_processes[s].channel[1]);if (ngx_nonblocking(ngx_processes[s].channel[0]) == -1) {ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,ngx_nonblocking_n " failed while spawning \"%s\"",name);ngx_close_channel(ngx_processes[s].channel, cycle->log);return NGX_INVALID_PID;}if (ngx_nonblocking(ngx_processes[s].channel[1]) == -1) {ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,ngx_nonblocking_n " failed while spawning \"%s\"",name);ngx_close_channel(ngx_processes[s].channel, cycle->log);return NGX_INVALID_PID;}on = 1;if (ioctl(ngx_processes[s].channel[0], FIOASYNC, &on) == -1) {ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,"ioctl(FIOASYNC) failed while spawning \"%s\"", name);ngx_close_channel(ngx_processes[s].channel, cycle->log);return NGX_INVALID_PID;}if (fcntl(ngx_processes[s].channel[0], F_SETOWN, ngx_pid) == -1) {ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,"fcntl(F_SETOWN) failed while spawning \"%s\"", name);ngx_close_channel(ngx_processes[s].channel, cycle->log);return NGX_INVALID_PID;}if (fcntl(ngx_processes[s].channel[0], F_SETFD, FD_CLOEXEC) == -1) {ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,"fcntl(FD_CLOEXEC) failed while spawning \"%s\"",name);ngx_close_channel(ngx_processes[s].channel, cycle->log);return NGX_INVALID_PID;}if (fcntl(ngx_processes[s].channel[1], F_SETFD, FD_CLOEXEC) == -1) {ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,"fcntl(FD_CLOEXEC) failed while spawning \"%s\"",name);ngx_close_channel(ngx_processes[s].channel, cycle->log);return NGX_INVALID_PID;}ngx_channel = ngx_processes[s].channel[1];} else {ngx_processes[s].channel[0] = -1;ngx_processes[s].channel[1] = -1;}ngx_process_slot = s;// 调用fork产生子进程pid = fork();switch (pid) {case -1:ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,"fork() failed while spawning \"%s\"", name);ngx_close_channel(ngx_processes[s].channel, cycle->log);return NGX_INVALID_PID;
// case 0:
//0 是子进程，开始执行worker进程的核心函数
// 获取父进程的pid，ngx_pid = ngx_getpid();proc(cycle, data);break;
// 这里是子进程的真正工作，无限循环
// proc = ngx_worker_process_cycle
// data = (void *) (intptr_t) i，即worker iddefault:break;}ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "start %s %P", name, pid);ngx_processes[s].pid = pid;ngx_processes[s].exited = 0;if (respawn >= 0) {return pid;}ngx_processes[s].proc = proc;ngx_processes[s].data = data;ngx_processes[s].name = name;ngx_processes[s].exiting = 0;switch (respawn) {case NGX_PROCESS_NORESPAWN:ngx_processes[s].respawn = 0;ngx_processes[s].just_spawn = 0;ngx_processes[s].detached = 0;break;case NGX_PROCESS_JUST_SPAWN:ngx_processes[s].respawn = 0;ngx_processes[s].just_spawn = 1;ngx_processes[s].detached = 0;break;case NGX_PROCESS_RESPAWN:ngx_processes[s].respawn = 1;ngx_processes[s].just_spawn = 0;ngx_processes[s].detached = 0;break;case NGX_PROCESS_JUST_RESPAWN:ngx_processes[s].respawn = 1;ngx_processes[s].just_spawn = 1;ngx_processes[s].detached = 0;break;case NGX_PROCESS_DETACHED:ngx_processes[s].respawn = 0;ngx_processes[s].just_spawn = 0;ngx_processes[s].detached = 1;break;}if (s == ngx_last_process) {ngx_last_process++;}return pid;
}

4. ngx_worker_process_cycle 子进程的回调函数

ngx_worker_process_cycle为子进程的回调函数，一切子进程的工作从这个方法开始。
Nginx的进程最终也是有事件驱动的，所有这个方法中，最终会调用ngx_process_events_and_timers事件驱动的核心函数

// 传递给ngx_spawn_process()，是worker进程的核心功能
// data实际上是进程号, (void *) (intptr_t) i
static void ngx_worker_process_cycle(ngx_cycle_t *cycle, void *data)
{// 把data再转换为进程序号ngx_int_t worker = (intptr_t) data;// 设置进程状态ngx_process = NGX_PROCESS_WORKER;ngx_worker = worker;// 这里把进程号赋值给全局变量// 读取核心配置，设置cpu优先级,core dump信息,unix运行的group/user// 切换工作路径,根据pid设置随机数种子// 调用所有模块的init_process,让模块进程初始化ngx_worker_process_init(cycle, worker);ngx_setproctitle("worker process");// 无限循环，处理事件和信号for ( ;; ) {if (ngx_exiting) {if (ngx_event_no_timers_left() == NGX_OK) {ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "exiting");ngx_worker_process_exit(cycle);}}ngx_log_debug0(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "worker cycle");// 这个是关键ngx_process_events_and_timers(cycle);if (ngx_terminate) {ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "exiting");ngx_worker_process_exit(cycle);}if (ngx_quit) {ngx_quit = 0;ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0,"gracefully shutting down");ngx_setproctitle("worker process is shutting down");if (!ngx_exiting) {ngx_exiting = 1;ngx_set_shutdown_timer(cycle);ngx_close_listening_sockets(cycle);ngx_close_idle_connections(cycle);}}if (ngx_reopen) {ngx_reopen = 0;ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "reopening logs");ngx_reopen_files(cycle, -1);}}
}

参考文章：

1.https://initphp.blog.csdn.net/article/details/52265752