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BUG/MEDIUM: checks: don't needlessly take the server lock in health_adjust()

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The server lock was taken preventively for anything in health_adjust(),
including the static config checks needed to detect that the lock was not
needed, while the function is always called on the response path to update
a server's status. This was responsible for huge contention causing a
performance drop of about 17% on 16 threads. Let's move the lock only
where it should be, i.e. inside the function around the critical sections
only. By doing this, a 16-thread process jumped back from 575 to 675 krps.

This should be backported to 2.3 as the situation degraded there, and
maybe later to 2.2.
This commit is contained in:
Willy Tarreau 2021-02-17 15:20:19 +01:00
parent 64ba5ebadc
commit 4e9df2737d
2 changed files with 14 additions and 13 deletions
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6
include/haproxy/check.h
View File

@ -60,15 +60,11 @@ void set_srv_agent_port(struct server *srv, int port);
*/
static inline void health_adjust(struct server *s, short status)
{
HA_SPIN_LOCK(SERVER_LOCK, &s->lock);
/* return now if observing nor health check is not enabled */
if (!s->observe || !s->check.task) {
HA_SPIN_UNLOCK(SERVER_LOCK, &s->lock);
if (!s->observe || !s->check.task)
return;
}
__health_adjust(s, status);
HA_SPIN_UNLOCK(SERVER_LOCK, &s->lock);
}
#endif /* _HAPROXY_CHECKS_H */

21
src/check.c
View File

@ -404,7 +404,7 @@ void check_notify_stopping(struct check *check)
}
/* note: use health_adjust() only, which first checks that the observe mode is
* enabled.
* enabled. This will take the server lock if needed.
*/
void __health_adjust(struct server *s, short status)
{
@ -444,6 +444,13 @@ void __health_adjust(struct server *s, short status)
chunk_printf(&trash, "Detected %d consecutive errors, last one was: %s",
s->consecutive_errors, get_analyze_status(status));
if (s->check.fastinter)
expire = tick_add(now_ms, MS_TO_TICKS(s->check.fastinter));
else
expire = TICK_ETERNITY;
HA_SPIN_LOCK(SERVER_LOCK, &s->lock);
switch (s->onerror) {
case HANA_ONERR_FASTINTER:
/* force fastinter - nothing to do here as all modes force it */
@ -476,16 +483,14 @@ void __health_adjust(struct server *s, short status)
break;
}
HA_SPIN_UNLOCK(SERVER_LOCK, &s->lock);
s->consecutive_errors = 0;
_HA_ATOMIC_ADD(&s->counters.failed_hana, 1);
if (s->check.fastinter) {
expire = tick_add(now_ms, MS_TO_TICKS(s->check.fastinter));
if (tick_is_lt(expire, s->check.task->expire)) {
s->check.task->expire = expire;
/* requeue check task with new expire */
task_queue(s->check.task);
}
if (tick_is_lt(expire, s->check.task->expire)) {
/* requeue check task with new expire */
task_schedule(s->check.task, expire);
}
}