threaded.c

Apache V2.0.15 Alpha For Linuxhttpd-2_0_15-alpha.tar.Z

    }
    my_info->pid = my_child_num;
    my_info->tid = i;
    my_info->sd = 0;
    apr_pool_create(&my_info->tpool, pchild);
    ap_update_child_status(my_child_num, i, SERVER_STARTING, 
                           (request_rec *) NULL);
    worker_thread(my_info);
}

static int make_child(server_rec *s, int slot) 
{
    int pid;

    if (slot + 1 > ap_max_daemons_limit) {
	ap_max_daemons_limit = slot + 1;
    }

    if (one_process) {
	set_signals();
        ap_scoreboard_image->parent[slot].pid = getpid();
	child_main(slot);
    }

    /* Tag this slot as occupied so that perform_idle_server_maintenance
     * doesn't try to steal it */
    (void) ap_update_child_status(slot, 0, SERVER_STARTING, (request_rec *) NULL);

    if ((pid = fork()) == -1) {
        ap_log_error(APLOG_MARK, APLOG_ERR, errno, s, "fork: Unable to fork new process");

        /* fork didn't succeed. Fix the scoreboard or else
         * it will say SERVER_STARTING forever and ever
         */
        (void) ap_update_child_status(slot, 0, SERVER_DEAD, (request_rec *) NULL);

	/* In case system resources are maxxed out, we don't want
	   Apache running away with the CPU trying to fork over and
	   over and over again. */
	sleep(10);

	return -1;
    }

    if (!pid) {
#ifdef AIX_BIND_PROCESSOR
      /* By default, AIX binds to a single processor.  This bit unbinds
	 children which will then bind to another CPU.
      */
#include <sys/processor.h>
        int status = bindprocessor(BINDPROCESS, (int)getpid(),
			       PROCESSOR_CLASS_ANY);
	if (status != OK)
	    ap_log_error(APLOG_MARK, APLOG_NOERRNO|APLOG_WARNING, errno, ap_server_conf,
			 "processor unbind failed %d", status);
#endif

        RAISE_SIGSTOP(MAKE_CHILD);

        apr_signal(SIGTERM, just_die);
        child_main(slot);

        clean_child_exit(0);
    }
    /* else */
    ap_scoreboard_image->parent[slot].pid = pid;
    return 0;
}

/* start up a bunch of children */
static void startup_children(int number_to_start)
{
    int i;

    for (i = 0; number_to_start && i < ap_daemons_limit; ++i) {
	if (ap_scoreboard_image->parent[i].pid != 0) {
	    continue;
	}
	if (make_child(ap_server_conf, i) < 0) {
	    break;
	}
	--number_to_start;
    }
}


/*
 * idle_spawn_rate is the number of children that will be spawned on the
 * next maintenance cycle if there aren't enough idle servers.  It is
 * doubled up to MAX_SPAWN_RATE, and reset only when a cycle goes by
 * without the need to spawn.
 */
static int idle_spawn_rate = 1;
#ifndef MAX_SPAWN_RATE
#define MAX_SPAWN_RATE	(32)
#endif
static int hold_off_on_exponential_spawning;

static void perform_idle_server_maintenance(void)
{
    int i, j;
    int idle_thread_count;
    short_score *ss;
    int free_length;
    int free_slots[MAX_SPAWN_RATE];
    int last_non_dead;
    int total_non_dead;
    apr_size_t one = 1;
    apr_status_t rv;

    /* initialize the free_list */
    free_length = 0;

    idle_thread_count = 0;
    last_non_dead = -1;
    total_non_dead = 0;

    ap_sync_scoreboard_image();
    for (i = 0; i < ap_daemons_limit; ++i) {
	/* Initialization to satisfy the compiler. It doesn't know
	 * that ap_threads_per_child is always > 0 */
	int status = SERVER_DEAD;
	int any_dying_threads = 0;
	int all_dead_threads = 1;
	int idle_thread_addition = 0;

	if (i >= ap_max_daemons_limit && free_length == idle_spawn_rate)
	    break;
	for (j = 0; j < ap_threads_per_child; j++) {
            ss = &ap_scoreboard_image->servers[i][j];
	    status = ss->status;

	    any_dying_threads = any_dying_threads || (status == SERVER_DEAD)
                                    || (status == SERVER_GRACEFUL);
	    all_dead_threads = all_dead_threads && (status == SERVER_DEAD);

	    /* We consider a starting server as idle because we started it
	     * at least a cycle ago, and if it still hasn't finished starting
	     * then we're just going to swamp things worse by forking more.
	     * So we hopefully won't need to fork more if we count it.
	     * This depends on the ordering of SERVER_READY and SERVER_STARTING.
	     */
	    if (status <= SERVER_READY) {
	        ++idle_thread_addition;
	    }
	}
	if (all_dead_threads && free_length < idle_spawn_rate) {
	    free_slots[free_length] = i;
	    ++free_length;
	}
	if (!all_dead_threads) {
            last_non_dead = i;
	}
        if (!any_dying_threads) {
            ++total_non_dead;
	    idle_thread_count += idle_thread_addition;
        }
    }
    ap_max_daemons_limit = last_non_dead + 1;

    if (idle_thread_count > max_spare_threads) {
        /* Kill off one child */
        char char_of_death = '!';
        if ((rv = apr_file_write(pipe_of_death_out, &char_of_death, &one)) != APR_SUCCESS) {
            ap_log_error(APLOG_MARK, APLOG_WARNING, rv, ap_server_conf, "write pipe_of_death");
        }
        idle_spawn_rate = 1;
    }
    else if (idle_thread_count < min_spare_threads) {
        /* terminate the free list */
        if (free_length == 0) {
	    /* only report this condition once */
	    static int reported = 0;
	    
	    if (!reported) {
	        ap_log_error(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, 0, ap_server_conf,
			     "server reached MaxClients setting, consider"
			     " raising the MaxClients setting");
		reported = 1;
	    }
	    idle_spawn_rate = 1;
	}
	else {
	    
	    if (idle_spawn_rate >= 8) {
	        ap_log_error(APLOG_MARK, APLOG_NOERRNO|APLOG_INFO, 0, ap_server_conf,
			     "server seems busy, (you may need "
			     "to increase StartServers, ThreadsPerChild "
                             "or Min/MaxSpareThreads), "
			     "spawning %d children, there are around %d idle "
                             "threads, and %d total children", idle_spawn_rate,
			     idle_thread_count, total_non_dead);
	    }
	    for (i = 0; i < free_length; ++i) {
	        make_child(ap_server_conf, free_slots[i]);
	    }
	    /* the next time around we want to spawn twice as many if this
	     * wasn't good enough, but not if we've just done a graceful
	     */
	    if (hold_off_on_exponential_spawning) {
	        --hold_off_on_exponential_spawning;
	    }
	    else if (idle_spawn_rate < MAX_SPAWN_RATE) {
	        idle_spawn_rate *= 2;
	    }
	}
    }
    else {
      idle_spawn_rate = 1;
    }
}

static void server_main_loop(int remaining_children_to_start)
{
    int child_slot;
    apr_wait_t status;
    apr_proc_t pid;
    int i;

    while (!restart_pending && !shutdown_pending) {
        ap_wait_or_timeout(&status, &pid, pconf);
        
        if (pid.pid != -1) {
            ap_process_child_status(&pid, status);
            /* non-fatal death... note that it's gone in the scoreboard. */
            child_slot = find_child_by_pid(&pid);
            if (child_slot >= 0) {
                for (i = 0; i < ap_threads_per_child; i++)
                    ap_update_child_status(child_slot, i, SERVER_DEAD, (request_rec *) NULL);
                
		if (remaining_children_to_start
		    && child_slot < ap_daemons_limit) {
		    /* we're still doing a 1-for-1 replacement of dead
                     * children with new children
                     */
		    make_child(ap_server_conf, child_slot);
		    --remaining_children_to_start;
		}
#if APR_HAS_OTHER_CHILD
	    }
	    else if (apr_proc_other_child_read(&pid, status) == 0) {
		/* handled */
#endif
	    }
	    else if (is_graceful) {
		/* Great, we've probably just lost a slot in the
		 * scoreboard.  Somehow we don't know about this child.
		 */
		ap_log_error(APLOG_MARK, APLOG_NOERRNO|APLOG_WARNING, 0,
		             ap_server_conf,
		             "long lost child came home! (pid %ld)",
		             (long)pid.pid);
	    }
	    /* Don't perform idle maintenance when a child dies,
             * only do it when there's a timeout.  Remember only a
             * finite number of children can die, and it's pretty
             * pathological for a lot to die suddenly.
             */
	    continue;
	}
	else if (remaining_children_to_start) {
	    /* we hit a 1 second timeout in which none of the previous
	     * generation of children needed to be reaped... so assume
	     * they're all done, and pick up the slack if any is left.
	     */
	    startup_children(remaining_children_to_start);
	    remaining_children_to_start = 0;
	    /* In any event we really shouldn't do the code below because
	     * few of the servers we just started are in the IDLE state
	     * yet, so we'd mistakenly create an extra server.
	     */
	    continue;
	}

	perform_idle_server_maintenance();
    }
}

int ap_mpm_run(apr_pool_t *_pconf, apr_pool_t *plog, server_rec *s)
{
    int remaining_children_to_start;
    apr_status_t rv;
    apr_size_t one = 1;

    pconf = _pconf;
    ap_server_conf = s;
    rv = apr_file_pipe_create(&pipe_of_death_in, &pipe_of_death_out, pconf);
    if (rv != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_ERR, rv,
                     (const server_rec*) ap_server_conf,
                     "apr_file_pipe_create (pipe_of_death)");
        exit(1);
    }

    if ((rv = apr_file_pipe_timeout_set(pipe_of_death_in, 0)) != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_ERR, rv,
                     (const server_rec*) ap_server_conf,
                     "apr_file_pipe_timeout_set (pipe_of_death)");
        exit(1);
    }
    ap_server_conf = s;
    if ((num_listensocks = ap_setup_listeners(ap_server_conf)) < 1) {
        /* XXX: hey, what's the right way for the mpm to indicate a fatal error? */
        ap_log_error(APLOG_MARK, APLOG_NOERRNO|APLOG_ALERT, 0, s,
            "no listening sockets available, shutting down");
        return 1;
    }
    ap_log_pid(pconf, ap_pid_fname);

    /* Initialize cross-process accept lock */
    lock_fname = apr_psprintf(_pconf, "%s.%u",
                             ap_server_root_relative(_pconf, lock_fname),
                             ap_my_pid);
    rv = apr_lock_create(&accept_mutex, APR_MUTEX, APR_LOCKALL,
                   lock_fname, _pconf);
    if (rv != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s,
                     "Couldn't create accept lock");
        return 1;
    }


    if (!is_graceful) {
        ap_create_scoreboard(pconf, SB_SHARED);
    }

    set_signals();
    /* Don't thrash... */
    if (max_spare_threads < min_spare_threads + ap_threads_per_child)
	max_spare_threads = min_spare_threads + ap_threads_per_child;

    /* If we're doing a graceful_restart then we're going to see a lot
     * of children exiting immediately when we get into the main loop
     * below (because we just sent them SIGWINCH).  This happens pretty
     * rapidly... and for each one that exits we'll start a new one until
     * we reach at least daemons_min_free.  But we may be permitted to
     * start more than that, so we'll just keep track of how many we're
     * supposed to start up without the 1 second penalty between each fork.
     */
    remaining_children_to_start = ap_daemons_to_start;
    if (remaining_children_to_start > ap_daemons_limit) {
	remaining_children_to_start = ap_daemons_limit;
    }
    if (!is_graceful) {
	startup_children(remaining_children_to_start);
	remaining_children_to_start = 0;
    }
    else {
	/* give the system some time to recover before kicking into
	    * exponential mode */
	hold_off_on_exponential_spawning = 10;