event: avoid possible hang in clean_child_exit

If the pthread_create failure isn't on the first worker thread,
another one is likely to hold the queue mutex already. The cleanup
of pchild will try to cleanup the queue and block on destroying
the condition.

ST_UNGRACEFUL as we have no listener thread yet.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1916241 13f79535-47bb-0310-9956-ffa450edef68

Author: covener

server/mpm/event/event.c

@@ -2749,6 +2749,7 @@ static void *APR_THREAD_FUNC start_threads(apr_thread_t * thd, void *dummy)
                              APLOGNO(03104)
                              "ap_thread_create: unable to create worker thread");
                 /* let the parent decide how bad this really is */
+                signal_threads(ST_UNGRACEFUL);
                 clean_child_exit(APEXIT_CHILDSICK);
             }
             threads_created++;