prefork MPM: Ignore mutex errors during graceful restart. For

certain types of mutexes (particularly SysV semaphores), we
should expect to occasionally fail to obtain or release the
mutex during restart processing.

These mutex failures seem to be a pretty rare occurrence, but
it was fatal.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@95665 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/CHANGES b/CHANGES
index e9f1bf7720c94819f355e6c593a501aaa6343112..32c3c828822946f71d9ec4da7639380a84d0150e 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -1,5 +1,10 @@
 Changes with Apache 2.0.38
 
+  *) prefork MPM: Ignore mutex errors during graceful restart.  For
+     certain types of mutexes (particularly SysV semaphores), we
+     should expect to occasionally fail to obtain or release the
+     mutex during restart processing.  [Jeff Trawick]
+
   *) Fix install-bindist.sh so that it finds any perl instead of just
      early perl 5.x versions.  This is consistent with a build/install
      from source, and it allows the perl scripts installed by a bindist 

diff --git a/server/mpm/prefork/prefork.c b/server/mpm/prefork/prefork.c
index 87c13f2775b8b6560a0b443e39e97379acc70117..3d13b13638cf6042e781ecad20a6d902e362acb5 100644 (file)
--- a/server/mpm/prefork/prefork.c
+++ b/server/mpm/prefork/prefork.c
@@ -172,6 +172,7 @@ static pid_t parent_pid;
 #ifndef MULTITHREAD
 static int my_child_num;
 #endif
+ap_generation_t volatile ap_my_generation=0;
 
 #ifdef TPF
 int tpf_child = 0;
@@ -239,8 +240,17 @@ static void accept_mutex_on(void)
 {
     apr_status_t rv = apr_proc_mutex_lock(accept_mutex);
     if (rv != APR_SUCCESS) {
-        ap_log_error(APLOG_MARK, APLOG_EMERG, rv, NULL, "couldn't grab the accept mutex");
-        exit(APEXIT_CHILDFATAL);
+        const char *msg = "couldn't grab the accept mutex";
+
+        if (ap_my_generation != 
+            ap_scoreboard_image->global->running_generation) {
+            ap_log_error(APLOG_MARK, APLOG_DEBUG, rv, NULL, msg);
+            clean_child_exit(0);
+        }
+        else {
+            ap_log_error(APLOG_MARK, APLOG_EMERG, rv, NULL, msg);
+            exit(APEXIT_CHILDFATAL);
+        }
     }
 }
 
@@ -248,8 +258,20 @@ static void accept_mutex_off(void)
 {
     apr_status_t rv = apr_proc_mutex_unlock(accept_mutex);
     if (rv != APR_SUCCESS) {
-        ap_log_error(APLOG_MARK, APLOG_EMERG, rv, NULL, "couldn't release the accept mutex");
-        exit(APEXIT_CHILDFATAL);
+        const char *msg = "couldn't release the accept mutex";
+
+        if (ap_my_generation != 
+            ap_scoreboard_image->global->running_generation) {
+            ap_log_error(APLOG_MARK, APLOG_DEBUG, rv, NULL, msg);
+            /* don't exit here... we have a connection to
+             * process, after which point we'll see that the
+             * generation changed and we'll exit cleanly
+             */
+        }
+        else {
+            ap_log_error(APLOG_MARK, APLOG_EMERG, rv, NULL, msg);
+            exit(APEXIT_CHILDFATAL);
+        }
     }
 }
 
@@ -364,7 +386,6 @@ static void just_die(int sig)
 static int volatile shutdown_pending;
 static int volatile restart_pending;
 static int volatile is_graceful;
-ap_generation_t volatile ap_my_generation=0;
 
 static void sig_term(int sig)
 {