worker流程
master进程模型核心函数ngx_master_process_cycle()中调用了创建子进程函数ngx_start_worker_processes()，该函数源代码例如以下
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");
ch.command = NGX_CMD_OPEN_CHANNEL;
/
for (i = 0; i < n; i++) {
/*ngx_spawn_process方法调用fork函数创建进程运行ngx_worker_process_cycle()函数，该函数是worker进程模型的核心*/
ngx_spawn_process(cycle, ngx_worker_process_cycle,
(void *) (intptr_t) i, "worker process", type);
/*
在ngx_spawn_process创建好一个worker进程返回后，master进程就将worker进程的pid、worker
进程在ngx_processes数组中的位置及channel[0]传递给前面已经创建好的worker进程。然后继续
循环開始创建下一个worker进程。
*/
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);
}
}
在剖析ngx_worker_process_cycle是怎样工作的之前我们了解master进程和worker进程之间的通信方式：master进程是监控进程。对worker进程监控和管理。master进程採用的是信号管理worker进程。worker进程收到信号时，信号处理函数ngx_signal_handler()就会运行。
对于worker进程的工作方法ngx_worker_process_cycle来说，它主要关注4个全局标志位：
sig_atomic_t ngx_terminate; //强制关闭进程
sig_atomic_t ngx_quit; //优雅地关闭进程（有唯一一段代码会设置它。就是接受到QUIT信号。ngx_quit仅仅有在首次设置为1,时，才会将ngx_exiting置为1）
ngx_uint_t ngx_exiting; //退出进程标志位
sig_atomic_t ngx_reopen; //又一次打开全部文件
当中ngx_terminate、ngx_quit 、ngx_reopen都将由ngx_signal_handler依据接受到的信号来设置，例如以下表所看到的。
ngx_exiting标志位仅由ngx_worker_cycle方法在退出时作为标志位使用。
信号 | 相应进程中全局标志位变量 | 意义 |
QUIT | ngx_quit | 优雅关闭进程 |
TERM或者INT | ngx_terminate | 强制关闭进程 |
USR1 | ngx_reopen | 又一次打开全部文件 |
如今我们来剖析ngx_worker_process_cycle()函数。能够对比下图来理解源码：
static void
ngx_worker_process_cycle(ngx_cycle_t *cycle, void *data)
{
ngx_int_t worker = (intptr_t) data;
ngx_uint_t i;
ngx_connection_t *c;
ngx_process = NGX_PROCESS_WORKER;
/*worker进程进入工作循环之前的初始化工作*/
ngx_worker_process_init(cycle, worker);
ngx_setproctitle("worker process");
#if (NGX_THREADS)
{
ngx_int_t n;
ngx_err_t err;
ngx_core_conf_t *ccf;
ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);
if (ngx_threads_n) {
if (ngx_init_threads(ngx_threads_n, ccf->thread_stack_size, cycle)
== NGX_ERROR)
{
/* fatal */
exit(2);
}
err = ngx_thread_key_create(&ngx_core_tls_key);
if (err != 0) {
ngx_log_error(NGX_LOG_ALERT, cycle->log, err,
ngx_thread_key_create_n " failed");
/* fatal */
exit(2);
}
for (n = 0; n < ngx_threads_n; n++) {
ngx_threads[n].cv = ngx_cond_init(cycle->log);
if (ngx_threads[n].cv == NULL) {
/* fatal */
exit(2);
}
if (ngx_create_thread((ngx_tid_t *) &ngx_threads[n].tid,
ngx_worker_thread_cycle,
(void *) &ngx_threads[n], cycle->log)
!= 0)
{
/* fatal */
exit(2);
}
}
}
}
#endif
for ( ;; ) {
/*ngx_exiting为1。在開始准备关闭worker金曾*/
if (ngx_exiting) {
c = cycle->connections;
for (i = 0; i < cycle->connection_n; i++) {
/* THREAD: lock */
/* 依据当前ngx_cycle_t中全部正在处理的连接。调用它们相应的关闭连接处理方法 */
if (c[i].fd != -1 && c[i].idle) {
c[i].close = 1;
c[i].read->handler(c[i].read);
}
}
/*
若ngx_event_timer_rbtree红黑树不为空表示还有事件须要处理。
否则，调用ngx_worker_process_exit，以调用全部模块的exit_process方法,销毁内存池
*/
if (ngx_event_timer_rbtree.root == ngx_event_timer_rbtree.sentinel)
{
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");
ngx_process_events_and_timers(cycle);
/*强制结束进程*/
if (ngx_terminate) {
ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "exiting");
/*调用全部模块的exit_process方法,销毁内存池*/
ngx_worker_process_exit(cycle);
}
/*优雅的关闭基进程*/
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) {
/*关闭全部的监听句柄并设置ngx_exiting标志*/
ngx_close_listening_sockets(cycle);
ngx_exiting = 1;
}
}
/*又一次打开全部文件*/
if (ngx_reopen) {
ngx_reopen = 0;
ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "reopening logs");
ngx_reopen_files(cycle, -1);
}
}
}
