Add comment explaining the startup mutex.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@723665 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/modules/cluster/mod_heartbeat.c b/modules/cluster/mod_heartbeat.c
index df530f6dd3b44e060af80ef208b0c6c4d14c1cf4..4eac07cffbaa4fcd7bd4f480dfb4725b2bad10f0 100644 (file)
--- a/modules/cluster/mod_heartbeat.c
+++ b/modules/cluster/mod_heartbeat.c
@@ -191,6 +191,9 @@ static void start_hb_worker(apr_pool_t *p, hb_ctx_t *ctx)
         return;
     }
 
+    /* This mutex fixes problems with a fast start/fast end, where the pool 
+     * cleanup was being invoked before the thread completely spawned. 
+     */
     apr_thread_mutex_lock(ctx->start_mtx);
 
     apr_pool_cleanup_register(p, ctx, hb_pool_cleanup, apr_pool_cleanup_null);