Commit 844964d8 authored by Yann Ylavic's avatar Yann Ylavic
Browse files

Merge r1821558, r1821561, r1821595 from trunk: 

mod_event: Let the listener thread do its maintenance job on resources shortage.

PR 61979.


Follow up to r1821558: CHANGES typo.


mpm_event: Follow up to r1821558.

Don't crash (in listener) if we can't create the ptrans allocator.


Submitted by: ylavic
Reviewed by: ylavic, jim, icing


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1823644 13f79535-47bb-0310-9956-ffa450edef68
parent 6f67b16e

CHANGES

+3 −0
Original line number Diff line number Diff line 
                                                         -*- coding: utf-8 -*-

Changes with Apache 2.4.30

 

  *) mpm_event: Let the listener thread do its maintenance job on resources

     shortage.  PR 61979.  [Yann Ylavic]



  *) mpm_event: Wakeup the listener to re-enable listening sockets.

     [Yann Ylavic]

server/mpm/event/event.c

+64 −42
Original line number Diff line number Diff line
@@ -177,7 +177,6 @@ static volatile int dying = 0; 
static volatile int workers_may_exit = 0;

static volatile int start_thread_may_exit = 0;

static volatile int listener_may_exit = 0;

static volatile int listeners_disabled = 0;

static int listener_is_wakeable = 0;        /* Pollset supports APR_POLLSET_WAKEABLE */

static int num_listensocks = 0;

static apr_int32_t conns_this_child;        /* MaxConnectionsPerChild, only access
@@ -441,6 +440,8 @@ static pid_t ap_my_pid; /* Linux getpid() doesn't work except in main 
static pid_t parent_pid;

static apr_os_thread_t *listener_os_thread;



static int ap_child_slot;       /* Current child process slot in scoreboard */



/* The LISTENER_SIGNAL signal will be sent from the main thread to the

 * listener thread to wake it up for graceful termination (what a child

 * process from an old generation does when the admin does "apachectl
@@ -454,23 +455,29 @@ static apr_os_thread_t *listener_os_thread; 
 */

static apr_socket_t **worker_sockets;



static void disable_listensocks(int process_slot)

static volatile apr_uint32_t listensocks_disabled;



static void disable_listensocks(void)

{

    int i;

    listeners_disabled = 1;

    if (apr_atomic_cas32(&listensocks_disabled, 1, 0) != 0) {

        return;

    }

    if (event_pollset) {

        for (i = 0; i < num_listensocks; i++) {

            apr_pollset_remove(event_pollset, &listener_pollfd[i]);

        }

    ap_scoreboard_image->parent[process_slot].not_accepting = 1;

    }

    ap_scoreboard_image->parent[ap_child_slot].not_accepting = 1;

}



static void enable_listensocks(int process_slot)

static void enable_listensocks(void)

{

    int i;

    if (listener_may_exit) {

    if (listener_may_exit

            || apr_atomic_cas32(&listensocks_disabled, 0, 1) != 1) {

        return;

    }

    listeners_disabled = 0;

    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf, APLOGNO(00457)

                 "Accepting new connections again: "

                 "%u active conns (%u lingering/%u clogged/%u suspended), "
@@ -486,7 +493,12 @@ static void enable_listensocks(int process_slot) 
     * XXX: This is not yet optimal. If many workers suddenly become available,

     * XXX: the parent may kill some processes off too soon.

     */

    ap_scoreboard_image->parent[process_slot].not_accepting = 0;

    ap_scoreboard_image->parent[ap_child_slot].not_accepting = 0;

}



static APR_INLINE apr_uint32_t listeners_disabled(void)

{

    return apr_atomic_read32(&listensocks_disabled);

}



static APR_INLINE int connections_above_limit(void)
@@ -496,9 +508,9 @@ static APR_INLINE int connections_above_limit(void) 
        apr_uint32_t c_count = apr_atomic_read32(&connection_count);

        apr_uint32_t l_count = apr_atomic_read32(&lingering_count);

        if (c_count <= l_count

                /* Off by 'listeners_disabled' to avoid flip flop */

                /* Off by 'listeners_disabled()' to avoid flip flop */

                || c_count - l_count < (apr_uint32_t)threads_per_child +

                                       (i_count - (listeners_disabled != 0)) *

                                       (i_count - listeners_disabled()) *

                                       (worker_factor / WORKER_FACTOR_SCALE)) {

            return 0;

        }
@@ -561,6 +573,7 @@ static void close_worker_sockets(void) 
static void wakeup_listener(void)

{

    listener_may_exit = 1;

    disable_listensocks();



    /* Unblock the listener if it's poll()ing */

    if (event_pollset && listener_is_wakeable) {
@@ -754,7 +767,7 @@ static apr_status_t decrement_connection_count(void *cs_) 
    is_last_connection = !apr_atomic_dec32(&connection_count);

    if (listener_is_wakeable

            && ((is_last_connection && listener_may_exit)

                || (listeners_disabled && !connections_above_limit()))) {

                || (listeners_disabled() && !connections_above_limit()))) {

        apr_pollset_wakeup(event_pollset);

    }

    return APR_SUCCESS;
@@ -1206,17 +1219,16 @@ static void check_infinite_requests(void) 
    }

}



static void close_listeners(int process_slot, int *closed)

static void close_listeners(int *closed)

{

    if (!*closed) {

        int i;

        disable_listensocks(process_slot);

        ap_close_listeners_ex(my_bucket->listeners);

        *closed = 1;

        dying = 1;

        ap_scoreboard_image->parent[process_slot].quiescing = 1;

        ap_scoreboard_image->parent[ap_child_slot].quiescing = 1;

        for (i = 0; i < threads_per_child; ++i) {

            ap_update_child_status_from_indexes(process_slot, i,

            ap_update_child_status_from_indexes(ap_child_slot, i,

                                                SERVER_GRACEFUL, NULL);

        }

        /* wake up the main thread */
@@ -1590,8 +1602,9 @@ static void * APR_THREAD_FUNC listener_thread(apr_thread_t * thd, void *dummy) 
    if (rc != APR_SUCCESS) {

        ap_log_error(APLOG_MARK, APLOG_ERR, rc, ap_server_conf,

                     "failed to initialize pollset, "

                     "attempting to shutdown process gracefully");

        signal_threads(ST_GRACEFUL);

                     "shutdown process now");

        resource_shortage = 1;

        signal_threads(ST_UNGRACEFUL);

        return NULL;

    }
@@ -1613,7 +1626,7 @@ static void * APR_THREAD_FUNC listener_thread(apr_thread_t * thd, void *dummy) 
            check_infinite_requests();



        if (listener_may_exit) {

            close_listeners(process_slot, &closed);

            close_listeners(&closed);

            if (terminate_mode == ST_UNGRACEFUL

                || apr_atomic_read32(&connection_count) == 0)

                break;
@@ -1699,7 +1712,7 @@ static void * APR_THREAD_FUNC listener_thread(apr_thread_t * thd, void *dummy) 
                 * need to update timeouts (logic is above, so simply restart

                 * the loop).

                 */

                if (!listener_may_exit && !listeners_disabled) {

                if (!listener_may_exit && !listeners_disabled()) {

                    continue;

                }

                timeout_time = 0;
@@ -1714,13 +1727,13 @@ static void * APR_THREAD_FUNC listener_thread(apr_thread_t * thd, void *dummy) 
        }



        if (listener_may_exit) {

            close_listeners(process_slot, &closed);

            close_listeners(&closed);

            if (terminate_mode == ST_UNGRACEFUL

                || apr_atomic_read32(&connection_count) == 0)

                break;

        }



        while (num) {

        for (; num; --num, ++out_pfd) {

            listener_poll_type *pt = (listener_poll_type *) out_pfd->client_data;

            if (pt->type == PT_CSD) {

                /* one of the sockets is readable */
@@ -1781,16 +1794,16 @@ static void * APR_THREAD_FUNC listener_thread(apr_thread_t * thd, void *dummy) 
                    ap_assert(0);

                }

            }

            else if (pt->type == PT_ACCEPT && !listeners_disabled) {

            else if (pt->type == PT_ACCEPT && !listeners_disabled()) {

                /* A Listener Socket is ready for an accept() */

                if (workers_were_busy) {

                    disable_listensocks(process_slot);

                    disable_listensocks();

                    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf,

                                 "All workers busy, not accepting new conns "

                                 "in this process");

                }

                else if (connections_above_limit()) {

                    disable_listensocks(process_slot);

                    disable_listensocks();

                    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf,

                                 "Too many open connections (%u), "

                                 "not accepting new conns in this process",
@@ -1808,22 +1821,31 @@ static void * APR_THREAD_FUNC listener_thread(apr_thread_t * thd, void *dummy) 


                    if (ptrans == NULL) {

                        /* create a new transaction pool for each accepted socket */

                        apr_allocator_t *allocator;

                        apr_allocator_t *allocator = NULL;



                        apr_allocator_create(&allocator);

                        rc = apr_allocator_create(&allocator);

                        if (rc == APR_SUCCESS) {

                            apr_allocator_max_free_set(allocator,

                                                       ap_max_mem_free);

                        apr_pool_create_ex(&ptrans, pconf, NULL, allocator);

                            rc = apr_pool_create_ex(&ptrans, pconf, NULL,

                                                    allocator);

                            if (rc == APR_SUCCESS) {

                                apr_pool_tag(ptrans, "transaction");

                                apr_allocator_owner_set(allocator, ptrans);

                        if (ptrans == NULL) {

                            }

                        }

                        if (rc != APR_SUCCESS) {

                            ap_log_error(APLOG_MARK, APLOG_CRIT, rc,

                                         ap_server_conf, APLOGNO(03097)

                                         "Failed to create transaction pool");

                            if (allocator) {

                                apr_allocator_destroy(allocator);

                            }

                            resource_shortage = 1;

                            signal_threads(ST_GRACEFUL);

                            return NULL;

                            continue;

                        }

                    }

                    apr_pool_tag(ptrans, "transaction");



                    get_worker(&have_idle_worker, 1, &workers_were_busy);

                    rc = lr->accept_func(&csd, lr, ptrans);
@@ -1850,9 +1872,7 @@ static void * APR_THREAD_FUNC listener_thread(apr_thread_t * thd, void *dummy) 
                    }

                }

            }               /* if:else on pt->type */

            out_pfd++;

            num--;

        }                   /* while for processing poll */

        } /* for processing poll */



        /* XXX possible optimization: stash the current time for use as

         * r->request_time for new requests
@@ -1924,14 +1944,14 @@ static void * APR_THREAD_FUNC listener_thread(apr_thread_t * thd, void *dummy) 
            }

        }



        if (listeners_disabled

        if (listeners_disabled()

                && !workers_were_busy

                && !connections_above_limit()) {

            enable_listensocks(process_slot);

            enable_listensocks();

        }

    } /* listener main loop */



    close_listeners(process_slot, &closed);

    close_listeners(&closed);

    ap_queue_term(worker_queue);



    apr_thread_exit(thd, APR_SUCCESS);
@@ -2379,6 +2399,7 @@ static void child_main(int child_num_arg, int child_bucket) 
    retained->mpm->mpm_state = AP_MPMQ_STARTING;



    ap_my_pid = getpid();

    ap_child_slot = child_num_arg;

    ap_fatal_signal_child_setup(ap_server_conf);

    apr_pool_create(&pchild, pconf);
@@ -3356,6 +3377,7 @@ static int event_pre_config(apr_pool_t * pconf, apr_pool_t * plog, 
    event_pollset = NULL;

    worker_queue_info = NULL;

    listener_os_thread = NULL;

    listensocks_disabled = 0;



    return OK;

}