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BUG: backend: stop looking for queued connections once there's no more

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Commit ae0b12ee0 ("MEDIUM: queue: use a trylock on the server's queue")
introduced a hard to trigger bug that's more visible with a single thread:
if a server dequeues a connection and finds another free slot with no
connection to place there, process_srv_queue() will never break out of
the loop. In multi-thread it almost does not happen because other threads
bring new connections.

No backport is needed as it's only in -dev.
This commit is contained in:
Willy Tarreau 2021-06-24 15:51:12 +02:00
parent d03adce575
commit 19c5581b43
1 changed files with 4 additions and 3 deletions
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7
src/queue.c
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@ -330,6 +330,7 @@ void process_srv_queue(struct server *s)
struct server *ref = s->track ? s->track : s;
struct proxy *p = s->proxy;
int maxconn;
int stop = 0;
int done = 0;
int px_ok;
@ -345,13 +346,13 @@ void process_srv_queue(struct server *s)
* for the same server will give up, knowing that at least one of
* them will check the conditions again before quitting.
*/
while (s->served < (maxconn = srv_dynamic_maxconn(s))) {
while (!stop && s->served < (maxconn = srv_dynamic_maxconn(s))) {
if (HA_SPIN_TRYLOCK(SERVER_LOCK, &s->queue.lock) != 0)
break;
while (s->served < maxconn) {
int ret = pendconn_process_next_strm(s, p, px_ok);
if (!ret)
stop = !pendconn_process_next_strm(s, p, px_ok);
if (stop)
break;
_HA_ATOMIC_INC(&s->served);
done++;