From: Willy Tarreau <w@1wt.eu>
Date: Wed, 13 May 2020 12:30:25 +0000 (+0200)
Subject: MINOR: soft-stop: let the first stopper only signal other threads
X-Git-Tag: v2.2-dev8~78
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d645574;p=thirdparty%2Fhaproxy.git

MINOR: soft-stop: let the first stopper only signal other threads

When the first thread stops and wakes others up, it's possible some of
them will also start to wake others in parallel. Let's make give this
notification task to the very first one instead since it's enough and
can reduce the amount of needless (though harmless) wakeup calls.
---

diff --git a/src/haproxy.c b/src/haproxy.c
index c3b7be6491..2675bf7157 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -2835,11 +2835,12 @@ void run_poll_loop()
 			int i;
 
 			if (stopping) {
-				_HA_ATOMIC_OR(&stopping_thread_mask, tid_bit);
-				/* notify all threads that stopping was just set */
-				for (i = 0; i < global.nbthread; i++)
-					if (((all_threads_mask & ~stopping_thread_mask) >> i) & 1)
-						wake_thread(i);
+				if (_HA_ATOMIC_OR(&stopping_thread_mask, tid_bit) == tid_bit) {
+					/* notify all threads that stopping was just set */
+					for (i = 0; i < global.nbthread; i++)
+						if ((all_threads_mask >> i) & 1)
+							wake_thread(i);
+				}
 			}
 
 			/* stop when there's nothing left to do */