mpm_event,mpm_worker: Comment about pollset sizing when APR_POLLSET_WAKEABLE.

Follow up to r1916925 and r1916926.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1916929 13f79535-47bb-0310-9956-ffa450edef68

Author: ylavic

server/mpm/event/event.c

@@ -2628,7 +2628,10 @@ static void setup_threads_runtime(void)
         clean_child_exit(APEXIT_CHILDFATAL);
     }
 
-    /* Create the main pollset */
+    /* Create the main pollset. When APR_POLLSET_WAKEABLE is asked we account
+     * for the wakeup pipe explicitely with pollset_size+1 because some pollset
+     * implementations don't do it implicitely in APR.
+     */
     pollset_flags = APR_POLLSET_THREADSAFE | APR_POLLSET_NOCOPY |
                     APR_POLLSET_WAKEABLE | APR_POLLSET_NODEFAULT;
     for (i = 0; i < sizeof(good_methods) / sizeof(good_methods[0]); i++) {

server/mpm/worker/worker.c

@@ -909,7 +909,10 @@ static void setup_threads_runtime(void)
         clean_child_exit(APEXIT_CHILDFATAL);
     }
 
-    /* Create the main pollset */
+    /* Create the main pollset. When APR_POLLSET_WAKEABLE is asked we account
+     * for the wakeup pipe explicitely with num_listensocks+1 because some
+     * pollset implementations don't do it implicitely in APR.
+     */
     pollset_flags = APR_POLLSET_NOCOPY | APR_POLLSET_WAKEABLE;
     rv = apr_pollset_create(&worker_pollset, num_listensocks + 1, pruntime,
                             pollset_flags);