ngx_master_process_cycle()函數,這個函數會啓動工作進程幹活,並且會處理信號量,處理的過程中會殺死或者創建新的進程,具體流程如下:
http://blog.csdn.net/xiaoliangsky/article/details/40866855
a) 阻塞所有nginx關心的信號;
b) 設置進程的title(如果你用ps –aux來查看就可以分清master與worker進程,這就是title的作用。);
c) 按照ngx_core_conf_t中worker_processes數,啓動若干個work進程;
d) 啓動一個緩衝管理進程;
e) 初始化幾個標誌:ngx_new_binary = 0; delay = 0; live = 1;
後面一個循環對不同的狀態進行不同處理,而那些狀態多數是進程收到的不同信號。下面是各個處理的詳解:
f) delay不爲0,如果收到SIGALRM信號ngx_sigalrm設爲1,將delay時間乘以2;最後設置一個實時類型的計時器;
h) 掛起當前進程,等到有信號,就會從掛起狀態退出,繼續執行;
i) 退出掛起狀態後,根據操作系統時間重新更新當前時間;
j) ngx_reap爲1(收到SIGCHLD信號,有worker退出(ngx_reap==1)),調用ngx_reap_children()回收子進程;
k) 如果子進程都退出了(!live)且當前進程收到ngx_signal_value(NGX_SHUTDOWN_SIGNAL)或ngx_signal_value(NGX_TERMINATE_SIGNAL)信號,本進程進行退出處理(ngx_master_process_exit());退出處理先刪除pid文件,然後將調用所有模塊的進程退出鉤子,銷燬內存池對象;
l) 如果ngx_terminate爲1,delay爲0,就設成50;如果delay>1000,向work進程發送SIGKILL信號,否則向work進程發送ngx_signal_value(NGX_TERMINATE_SIGNAL)信號;
m) 如果ngx_quit爲1,向work進程發送ngx_signal_value(NGX_SHUTDOWN_SIGNAL)信號,然後將所有全局listening中的socket全關閉;continue;
n) 如果ngx_reconfigure爲1(ngx_signal_value(NGX_RECONFIGURE_SIGNAL)信號對應),就重新讀取config文件;重新創建並初始化ngx_cycle對象,啓動work進程,啓動緩衝管理進程,將live設爲1,調用ngx_signal_worker_processes()發送ngx_signal_value(NGX_SHUTDOWN_SIGNAL)信號;
o) ngx_new_binary爲1(表示是新啓動的一個進程),啓動work進程,啓動緩衝管理進程,然後將ngx_noaccepting設0;continue;
p) 如果ngx_restart爲1(當ngx_noaccepting=1的時候會把ngx_restart設爲1,重啓worker),啓動work進程,啓動緩衝管理進程,live設爲1;
q) 如果ngx_reopen爲1(ngx_signal_value(NGX_REOPEN_SIGNAL)信號對應),則重新找開log文件,調用ngx_signal_worker_processes()發送ngx_signal_value(NGX_REOPEN_SIGNAL)信號;
r) 如果ngx_change_binary爲1(ngx_signal_value(NGX_CHANGEBIN_SIGNAL)信號對應),調用ngx_exec_new_binary()執行新進程;
s) 如果ngx_noaccept爲1(ngx_signal_value(NGX_NOACCEPT_SIGNAL)對應),設ngx_noaccepting爲1,調用ngx_signal_worker_processes()發送ngx_signal_value(NGX_SHUTDOWN_SIGNAL)信號。
下面來看代碼:
1.首先屏蔽一些處理信號,因爲woker進程沒有創建,這些信息暫不處理
/*master 進程設置的要處理的信號*/
sigemptyset(&set);//將信號集初始化爲空
sigaddset(&set, SIGCHLD);//子進程退出發送的信號
sigaddset(&set, SIGALRM);//
sigaddset(&set, SIGIO);//異步IO
sigaddset(&set, SIGINT);//終端信號
sigaddset(&set, ngx_signal_value(NGX_RECONFIGURE_SIGNAL));//SIGHUP,重新讀取配置
sigaddset(&set, ngx_signal_value(NGX_REOPEN_SIGNAL));//SIGUSR1,重新打開所有已經打開的文件
sigaddset(&set, ngx_signal_value(NGX_NOACCEPT_SIGNAL));//SIGWINCH,debug
sigaddset(&set, ngx_signal_value(NGX_TERMINATE_SIGNAL));//SIGTERM,程序終止信號
sigaddset(&set, ngx_signal_value(NGX_SHUTDOWN_SIGNAL));//SIGQUIT,優雅退出信號
sigaddset(&set, ngx_signal_value(NGX_CHANGEBIN_SIGNAL));//SIGUSR2,打開新的二進制執行文件信號
if (sigprocmask(SIG_BLOCK, &set, NULL) == -1) {//屏蔽set信號集中的信號
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
"sigprocmask() failed");
}
2然後設置進程標題:
/*調用ngx_setproctilte設置進程標題,title = "master process" + ngx_argv[0] + ... + ngx_argv[ngx_argc-1];
*/
size = sizeof(master_process);
for (i = 0; i < ngx_argc; i++) {
size += ngx_strlen(ngx_argv[i]) + 1;
}
title = ngx_pnalloc(cycle->pool, size);
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);
3啓動woker進程和一個啓動緩衝管理進程:
/*啓動worker進程*/
ngx_start_worker_processes(cycle, ccf->worker_processes,
NGX_PROCESS_RESPAWN);
/*調用ngx_start_cache_manager_processes(cycle, 0)啓動文件cache管理進程,有些模塊需要文件cache,比如fastcgi模塊,這些模塊會把文件cache路徑添加到cycle->paths中,文件cache管理進程會定期調用這些模塊的文件cache處理鉤子處理一下文件cache;*/
ngx_start_cache_manager_processes(cycle, 0);
4master循環處理信號:
ngx_new_binary = 0;
delay = 0;
sigio = 0;
live = 1;
for ( ;; ) {
//delay用來設置等待worker進程退出的時間,master接受退出信號後,
//首先發送退出信號給worker,而worker退出需要一些時間
if (delay) {
if (ngx_sigalrm) {
sigio = 0;
delay *= 2;
ngx_sigalrm = 0;
}
ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
"termination cycle: %d", 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;
//設置定時器,以系統真實時間來計算,送出SIGALRM信號
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");
//每次處理完一個信號,master進程會被掛起,直到有新的信號到來
sigsuspend(&set);
ngx_time_update();
ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
"wake up, sigio %i", sigio);
//收到了SIGCHLD信號,有worker異常退出(ngx_reap == 1)
if (ngx_reap) {
ngx_reap = 0;
ngx_log_debug0(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "reap children");
//處理所有worker,如果有worker異常退出,則重啓這個worker進程,
//如果所有worker進程都退出了,則返回0
live = ngx_reap_children(cycle);
}
//如果所有worker進程都退出了,並且收到SIGTERM信號或SIGINT信號或SIGQUIT信號等,
//master進程開始處理退出
if (!live && (ngx_terminate || ngx_quit)) {
ngx_master_process_exit(cycle);
}
//並且收到SIGTERM信號或SIGINT信號退出信號,設置推出延遲時間
if (ngx_terminate) {
if (delay == 0) {
delay = 50;
}
if (sigio) {
sigio--;
continue;
}
//總的子進程個數
sigio = ccf->worker_processes + 2 /* cache processes */;
if (delay > 1000) {
//延時大於1000,給所有worker進程發送SIGKILL,強制殺死所有worker進程
ngx_signal_worker_processes(cycle, SIGKILL);
} else {
//給所有worker進程發送SIGTERM信號,通知worker退出
ngx_signal_worker_processes(cycle,
ngx_signal_value(NGX_TERMINATE_SIGNAL));
}
continue;
}
//收到SIGQUIT信號
if (ngx_quit) {//給所有worker進程發送SIGQUIT信號
ngx_signal_worker_processes(cycle,
ngx_signal_value(NGX_SHUTDOWN_SIGNAL));
//關閉所有監聽套接字socket
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;
}
//收到SIGHUP信號,
if (ngx_reconfigure) {
ngx_reconfigure = 0;
//如果是平滑升級程序,則重啓worker進程,不許要重新初始化配置
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");
//不是平滑升級,重新讀取配置
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);
//重啓worker進程
ngx_start_worker_processes(cycle, ccf->worker_processes,
NGX_PROCESS_JUST_RESPAWN);
ngx_start_cache_manager_processes(cycle, 1);
live = 1;
//向所有的old worker進程發送SIGQUIT信號
ngx_signal_worker_processes(cycle,
ngx_signal_value(NGX_SHUTDOWN_SIGNAL));
}
if (ngx_restart) {//重啓
ngx_restart = 0;
ngx_start_worker_processes(cycle, ccf->worker_processes,
NGX_PROCESS_RESPAWN);
ngx_start_cache_manager_processes(cycle, 0);
live = 1;
}
//收到SIGUSR1信號
if (ngx_reopen) {//重新打開所有的文件
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));
}
//收到SIGUSR2信號,熱帶碼替換
if (ngx_change_binary) {//執行新的程序
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);//平滑升級標誌
}
//收到SIGWINCH信號不再接受請求,向所有worker進程發送SIGQUIT
if (ngx_noaccept) {
ngx_noaccept = 0;
ngx_noaccepting = 1;
//worker進程優雅退出
ngx_signal_worker_processes(cycle,
ngx_signal_value(NGX_SHUTDOWN_SIGNAL));
}
}
master進程做的主要工作是啓動woker進程,並根據信號來管理worker進程,而事件處理則交給woker進程來處理。
參考:
http://blog.csdn.net/lu_ming/article/details/5144427