From: Frederic Lecaille <flecaille@haproxy.com>
Date: Fri, 21 Aug 2026 16:26:38 +0000 (+0200)
Subject: BUG/MINOR: haload: split the rate exactly across threads
X-Git-Tag: v3.5-dev6~83
X-Git-Url: https://git.kaiwu.me/?a=commitdiff_plain;h=98093c5105fdc7b04c7ceb3348f010fa52ac1986;p=haproxy.git

BUG/MINOR: haload: split the rate exactly across threads

hld_usr_schedule() and hld_rate_task() gave every thread ceil(rate /
arg_thrd), so a low rate on a machine with many threads was quietly
served several times over (e.g. rate=1 on 200 threads gave ~200 req/s
instead of 1). Use the same exact split already used elsewhere in
haload (thread <tid> gets (rate + tid) / arg_thrd): most threads then
get 0 and only <rate> of them get 1, so the total always matches
<rate> regardless of the thread count.

A thread with no budget now just checks back in 1s instead of being
bumped to 1 by the old max ? max : 1 fallback.
---

diff --git a/src/haload.c b/src/haload.c
index fa44cd931..0dbae94c6 100644
--- a/src/haload.c
+++ b/src/haload.c
@@ -1413,11 +1413,19 @@ static inline void hld_usr_schedule(struct hld_usr *usr, int rate)
 	if (ti->curusrs < maxusrs && throttle)
 		max = 0;
 	else if (throttle)
-		max = (mul32hi(rate, throttle) + arg_thrd - 1) / arg_thrd;
+		max = (mul32hi(rate, throttle) + tid) / arg_thrd;
 	else
-		max = (rate + arg_thrd - 1) / arg_thrd;
+		max = (rate + tid) / arg_thrd;
+
+	if (!max) {
+		/* this thread has no budget right now (its exact share of
+		 * <rate> is 0, or it's still ramping up under -s): nothing
+		 * to send from here, just check back shortly.
+		 */
+		task_schedule(usr->task, tick_add(now_ms, MS_TO_TICKS(1000)));
+		return;
+	}
 
-	max = max ? max : 1;
 	wait = hld_next_event_delay(&ti->req_rate, max,
 	                            ti->curusrs - ti->cur_req, date);
 	task_schedule(usr->task, tick_add(now_ms, MS_TO_TICKS(wait)));