Commit e7cf20d7 authored by Jeff Trawick's avatar Jeff Trawick
Browse files

mpm_event, mpm_worker: Remain active amidst prevalent child process 

resource shortages.

Submitted by: trawick
Reviewed by: wrowe, rjung


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@1374330 13f79535-47bb-0310-9956-ffa450edef68
parent 3f05127d

CHANGES

+3 −0
Original line number Diff line number Diff line
@@ -5,6 +5,9 @@ Changes with Apache 2.2.23 
     envvars: Fix insecure handling of LD_LIBRARY_PATH that could lead to the

     current working directory to be searched for DSOs. [Stefan Fritsch]



  *) mpm_event, mpm_worker: Remain active amidst prevalent child process

     resource shortages.  [Jeff Trawick]



  *) mod_proxy_balancer: Restore balancing after a failed worker has

     recovered when using lbmethod_bybusyness.  PR 48735.  [Jeff Trawick]

STATUS

+0 −8
Original line number Diff line number Diff line
@@ -112,14 +112,6 @@ PATCHES ACCEPTED TO BACKPORT FROM TRUNK: 
    2.2.x patch: http://people.apache.org/~jim/patches/mod_proxy_ajp-erroroverride.patch

    +1: igalic, jim, rpluem



   * mpm_event, mpm_worker: Remain active amidst prevalent child process

     resource shortages.

     trunk patch: http://svn.apache.org/viewvc?rev=1363557&view=rev

     trunk patch: http://svn.apache.org/viewvc?rev=1364601&view=rev

     2.4.x patch: trunk patch works

     2.2.x patch: http://people.apache.org/~trawick/r1363557_1364601_to_2.2.x.txt

     +1: trawick, wrowe, rjung



PATCHES PROPOSED TO BACKPORT FROM TRUNK:

  [ New proposals should be added at the end of the list ]

server/mpm/experimental/event/event.c

+16 −7
Original line number Diff line number Diff line
@@ -148,6 +148,7 @@ static int ap_daemons_limit = 0; 
static int server_limit = DEFAULT_SERVER_LIMIT;

static int first_server_limit = 0;

static int thread_limit = DEFAULT_THREAD_LIMIT;

static int had_healthy_child = 0;

static int first_thread_limit = 0;

static int changed_limit_at_restart;

static int dying = 0;
@@ -1657,6 +1658,7 @@ static void perform_idle_server_maintenance(void) 
        int any_dying_threads = 0;

        int any_dead_threads = 0;

        int all_dead_threads = 1;

        int child_threads_active = 0;



        if (i >= ap_max_daemons_limit

            && totally_free_length == idle_spawn_rate)
@@ -1686,10 +1688,11 @@ static void perform_idle_server_maintenance(void) 
                    ++idle_thread_count;

                }

                if (status >= SERVER_READY && status < SERVER_GRACEFUL) {

                    ++active_thread_count;

                    ++child_threads_active;

                }

            }

        }

        active_thread_count += child_threads_active;

        if (any_dead_threads

            && totally_free_length < idle_spawn_rate

            && free_length < MAX_SPAWN_RATE
@@ -1713,6 +1716,9 @@ static void perform_idle_server_maintenance(void) 
            }

            ++free_length;

        }

        else if (child_threads_active == ap_threads_per_child) {

            had_healthy_child = 1;

        }

        /* XXX if (!ps->quiescing)     is probably more reliable  GLA */

        if (!any_dying_threads) {

            last_non_dead = i;
@@ -1721,21 +1727,23 @@ static void perform_idle_server_maintenance(void) 
    }



    if (sick_child_detected) {

        if (active_thread_count > 0) {

            /* some child processes appear to be working.  don't kill the

             * whole server.

        if (had_healthy_child) {

            /* Assume this is a transient error, even though it may not be.  Leave

             * the server up in case it is able to serve some requests or the

             * problem will be resolved.

             */

            sick_child_detected = 0;

        }

        else {

            /* looks like a basket case.  give up.

            /* looks like a basket case, as no child ever fully initialized; give up.

             */

            shutdown_pending = 1;

            child_fatal = 1;

            ap_log_error(APLOG_MARK, APLOG_ALERT, 0,

                         ap_server_conf,

                         "No active workers found..."

                         " Apache is exiting!");

                         "A resource shortage or other unrecoverable failure "

                         "was encountered before any child process initialized "

                         "successfully... httpd is exiting!");

            /* the child already logged the failure details */

            return;

        }
@@ -2198,6 +2206,7 @@ static int worker_pre_config(apr_pool_t * pconf, apr_pool_t * plog, 
    ap_pid_fname = DEFAULT_PIDLOG;

    ap_lock_fname = DEFAULT_LOCKFILE;

    ap_max_requests_per_child = DEFAULT_MAX_REQUESTS_PER_CHILD;

    had_healthy_child = 0;

    ap_extended_status = 0;

#ifdef AP_MPM_WANT_SET_MAX_MEM_FREE

    ap_max_mem_free = APR_ALLOCATOR_MAX_FREE_UNLIMITED;

server/mpm/worker/worker.c

+16 −7
Original line number Diff line number Diff line
@@ -124,6 +124,7 @@ static int first_server_limit = 0; 
static int thread_limit = DEFAULT_THREAD_LIMIT;

static int first_thread_limit = 0;

static int changed_limit_at_restart;

static int had_healthy_child = 0;

static int dying = 0;

static int workers_may_exit = 0;

static int start_thread_may_exit = 0;
@@ -1419,6 +1420,7 @@ static void perform_idle_server_maintenance(void) 
        int any_dying_threads = 0;

        int any_dead_threads = 0;

        int all_dead_threads = 1;

        int child_threads_active = 0;



        if (i >= ap_max_daemons_limit && totally_free_length == idle_spawn_rate)

            break;
@@ -1449,10 +1451,11 @@ static void perform_idle_server_maintenance(void) 
                    ++idle_thread_count;

                }

                if (status >= SERVER_READY && status < SERVER_GRACEFUL) {

                    ++active_thread_count;

                    ++child_threads_active;

                }

            }

        }

        active_thread_count += child_threads_active;

        if (any_dead_threads && totally_free_length < idle_spawn_rate

                && free_length < MAX_SPAWN_RATE

                && (!ps->pid               /* no process in the slot */
@@ -1475,6 +1478,9 @@ static void perform_idle_server_maintenance(void) 
            }

            ++free_length;

        }

        else if (child_threads_active == ap_threads_per_child) {

            had_healthy_child = 1;

        }

        /* XXX if (!ps->quiescing)     is probably more reliable  GLA */

        if (!any_dying_threads) {

            last_non_dead = i;
@@ -1483,21 +1489,23 @@ static void perform_idle_server_maintenance(void) 
    }



    if (sick_child_detected) {

        if (active_thread_count > 0) {

            /* some child processes appear to be working.  don't kill the

             * whole server.

        if (had_healthy_child) {

            /* Assume this is a transient error, even though it may not be.  Leave

             * the server up in case it is able to serve some requests or the

             * problem will be resolved.

             */

            sick_child_detected = 0;

        }

        else {

            /* looks like a basket case.  give up.

            /* looks like a basket case, as no child ever fully initialized; give up.

             */

            shutdown_pending = 1;

            child_fatal = 1;

            ap_log_error(APLOG_MARK, APLOG_ALERT, 0,

                         ap_server_conf,

                         "No active workers found..."

                         " Apache is exiting!");

                         "A resource shortage or other unrecoverable failure "

                         "was encountered before any child process initialized "

                         "successfully... httpd is exiting!");

            /* the child already logged the failure details */

            return;

        }
@@ -2011,6 +2019,7 @@ static int worker_pre_config(apr_pool_t *pconf, apr_pool_t *plog, 
    ap_pid_fname = DEFAULT_PIDLOG;

    ap_lock_fname = DEFAULT_LOCKFILE;

    ap_max_requests_per_child = DEFAULT_MAX_REQUESTS_PER_CHILD;

    had_healthy_child = 0;

    ap_extended_status = 0;

#ifdef AP_MPM_WANT_SET_MAX_MEM_FREE

        ap_max_mem_free = APR_ALLOCATOR_MAX_FREE_UNLIMITED;