Commit c69524da authored by Colm MacCarthaigh's avatar Colm MacCarthaigh
Browse files 

Implement a "graceful-stop" for the prefork MPM (might aswell do the hard one
first). 

General approach is to send SIGUSR1 to all children (which will de-listen, and
exit when finished), and to gather all children as they exit. 

We don't use a sleep(timeout) for the timeout implementation, because this
would lead to a rut of defunct children until the timeout had expired.

set_graceful_shutdown stolen from Ken Coar. See <3E84B1EC.3050007@Golux.Com>
(28 Mar 2003).



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@240270 13f79535-47bb-0310-9956-ffa450edef68
parent 25da38ba

CHANGES

+4 −0
Original line number Diff line number Diff line
@@ -2,6 +2,10 @@ 
Changes with Apache 2.3.0

  [Remove entries to the current 2.0 and 2.2 section below, when backported]













  *) prefork: Support a graceful-stop procedure. Server will wait until













     existing requests are finished or until "GracefulShutdownTimeout" 













     before exiting. [Colm MacCarthaigh, Ken Coar]



























  *) mod_cgid: Append .PID to the script socket filename and remove the















     script socket on exit. [Colm MacCarthaigh]















































server/mpm/prefork/mpm.h



+1
−0






























Original line number
Diff line number
Diff line








@@ -39,6 +39,7 @@













#define AP_MPM_WANT_SET_MAX_MEM_FREE















#define AP_MPM_WANT_FATAL_SIGNAL_HANDLER















#define AP_MPM_DISABLE_NAGLE_ACCEPTED_SOCK













#define AP_MPM_SUPPORTS_GRACEFUL_STOP































#define AP_MPM_USES_POD 1















#define MPM_CHILD_PID(i) (ap_scoreboard_image->parent[i].pid)

































server/mpm/prefork/prefork.c



+125
−2






























Original line number
Diff line number
Diff line








@@ -96,6 +96,7 @@ static int ap_daemons_to_start=0;













static int ap_daemons_min_free=0;















static int ap_daemons_max_free=0;















static int ap_daemons_limit=0;      /* MaxClients */













static int graceful_shutdown_timeout = 0;















static int server_limit = DEFAULT_SERVER_LIMIT;















static int first_server_limit;















static int changed_limit_at_restart;










@@ -334,6 +335,9 @@ static void just_die(int sig)













static void stop_listening(int sig)















{















    ap_close_listeners();



























    /* For a graceful stop, we want the child to exit when done */













    die_now = 1;















}































/* volatile just in case */









@@ -351,6 +355,7 @@ static void sig_term(int sig)













        return;















    }















    shutdown_pending = 1;













    is_graceful = (sig == AP_SIG_GRACEFUL_STOP);















}































/* restart() is the signal handler for SIGHUP and AP_SIG_GRACEFUL










@@ -383,6 +388,11 @@ static void set_signals(void)













    sa.sa_handler = sig_term;















    if (sigaction(SIGTERM, &sa, NULL) < 0)















        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(SIGTERM)");













#ifdef AP_SIG_GRACEFUL_STOP













    if (sigaction(AP_SIG_GRACEFUL_STOP, &sa, NULL) < 0)













        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, 













                     "sigaction(" AP_SIG_GRACEFUL_STOP_STRING ")");













#endif















#ifdef SIGINT















    if (sigaction(SIGINT, &sa, NULL) < 0)















        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(SIGINT)");










@@ -430,6 +440,9 @@ static void set_signals(void)













#ifdef AP_SIG_GRACEFUL















    apr_signal(AP_SIG_GRACEFUL, restart);















#endif /* AP_SIG_GRACEFUL */













#ifdef AP_SIG_GRACEFUL_STOP













    apr_signal(AP_SIG_GRACEFUL_STOP, sig_term);













#endif /* AP_SIG_GRACEFUL */















#ifdef SIGPIPE















    apr_signal(SIGPIPE, SIG_IGN);















#endif /* SIGPIPE */










@@ -1074,8 +1087,8 @@ int ap_mpm_run(apr_pool_t *_pconf, apr_pool_t *plog, server_rec *s)





























    mpm_state = AP_MPMQ_STOPPING;





























    if (shutdown_pending) {













        /* Time to gracefully shut down:













    if (shutdown_pending && !is_graceful) {













        /* Time to shut down:















         * Kill child processes, tell them to call child_exit, etc...















         */















        if (unixd_killpg(getpgrp(), SIGTERM) < 0) {









@@ -1096,6 +1109,103 @@ int ap_mpm_run(apr_pool_t *_pconf, apr_pool_t *plog, server_rec *s)





























        ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, ap_server_conf,















                    "caught SIGTERM, shutting down");



























        return 1;













    } else if (shutdown_pending) {













        /* Time to perform a graceful shut down:













         * Reap the inactive children, and ask the active ones













         * to close their listeners, then wait until they are













         * all done to exit.













         */













        int active_children;













        apr_exit_why_e exitwhy;













        int status;













        int child_slot;













        apr_proc_t pid;













        apr_time_t cutoff;



























        /* Stop listening */













        ap_close_listeners();



























        /* kill off the idle ones */













        ap_mpm_pod_killpg(pod, ap_max_daemons_limit);



























        /* Send SIGUSR1 to the active children */













        active_children = 0;













        for (index = 0; index < ap_daemons_limit; ++index) {













            if (ap_scoreboard_image->servers[index][0].status != SERVER_DEAD) {













                ap_scoreboard_image->servers[index][0].status = SERVER_GRACEFUL;













                /* Ask each child to close its listeners. */













                kill(ap_scoreboard_image->parent[index].pid, AP_SIG_GRACEFUL);













                active_children++;













            }













        }



























        /* Allow each child which actually finished to exit */













        for (; active_children; active_children--) {













            ap_wait_or_timeout(&exitwhy, &status, &pid, pconf);













            













            if (pid.pid != -1) {













                child_slot = find_child_by_pid(&pid);













                if (child_slot >= 0) {













                    (void) ap_update_child_status_from_indexes(child_slot, 0, 













                                            SERVER_DEAD, (request_rec *) NULL);













                }













            }













        }



























        /* cleanup pid file */













        {













            const char *pidfile = NULL;













            pidfile = ap_server_root_relative (pconf, ap_pid_fname);













            if ( pidfile != NULL && unlink(pidfile) == 0)













                ap_log_error(APLOG_MARK, APLOG_INFO,













                                0, ap_server_conf,













                                "removed PID file %s (pid=%ld)",













                                pidfile, (long)getpid());













        }



























        ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, ap_server_conf,













           "caught " AP_SIG_GRACEFUL_STOP_STRING ", shutting down gracefully");



























        if (graceful_shutdown_timeout) {













            cutoff = apr_time_now() + 













                     apr_time_from_sec(graceful_shutdown_timeout);













        }



























        /* Don't really exit until each child has finished */













        shutdown_pending = 0;













        do {













            active_children = 0;













            for (index = 0; index < ap_daemons_limit; ++index) {













                if (ap_scoreboard_image->servers[index][0].status != SERVER_DEAD) {













                    if (kill(ap_scoreboard_image->parent[index].pid, 0) == 0) {













                        active_children++;













                    }













                }













            }



























            for (index = 0; index < active_children; ++index) {













                /* Gather any now finished children */













                ap_wait_or_timeout(&exitwhy, &status, &pid, pconf);



























                if (pid.pid != -1) {













                    child_slot = find_child_by_pid(&pid);













                    if (child_slot >= 0) {













                        (void) ap_update_child_status_from_indexes(child_slot, 













                                         0, SERVER_DEAD, (request_rec *) NULL);













                    }













                }













            }













        } while (!shutdown_pending && active_children &&













                 (!graceful_shutdown_timeout || apr_time_now() < cutoff));



























        /* We might be here because we received SIGTERM, either













         * way, try and make sure that all of our processes are













         * really dead.













         */













        unixd_killpg(getpgrp(), SIGTERM);





























        return 1;















    }


























@@ -1363,6 +1473,16 @@ static const char *set_server_limit (cmd_parms *cmd, void *dummy, const char *ar













    return NULL;















}





























static const char *set_graceful_shutdown(cmd_parms *cmd, void *dummy, const char *arg) 













{













    const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);













    if (err != NULL) {













        return err;













    }













    graceful_shutdown_timeout = atoi(arg);













    return NULL;













}





























static const command_rec prefork_cmds[] = {















UNIX_DAEMON_COMMANDS,















LISTEN_COMMANDS,









@@ -1376,6 +1496,9 @@ AP_INIT_TAKE1("MaxClients", set_max_clients, NULL, RSRC_CONF,













              "Maximum number of children alive at the same time"),















AP_INIT_TAKE1("ServerLimit", set_server_limit, NULL, RSRC_CONF,















              "Maximum value of MaxClients for this run of Apache"),













AP_INIT_TAKE1("GracefulShutdownTimeout", set_graceful_shutdown, NULL, RSRC_CONF,













              "Time in seconds to wait for child processes to complete " 













              "transactions during shutdown"),















{ NULL }















};