Willy Tarreau 1a8f3a368f MINOR: queue: add a function to check for TOCTOU after queueing ... There's a rare TOCTOU case that happens from time to time with maxconn 1 and multiple threads. Between the moment we see the queue full and the moment we queue a request, it's possible that the last request on the server or proxy ended and that no other one is left to offer it its place. Given that all this code path is performance-critical and we cannot afford to increase the lock duration, better recheck for the condition after queueing. For this we need to be able to check for the condition and cleanly dequeue a request. That's what this patch provides via the new function pendconn_must_try_again(). It will catch more requests than absolutely needed though it will catch them all. It may find that around 1/1000 of requests are at risk, though testing shows that in practice, it's around 1 per million that really gets stuck (other ones benefit from timing and finishing late requests). Maybe in the future some conditions might be refined but it's harmless. What happens to such requests is that they're dequeued and their pendconn freed, so that the caller can decide to try to LB or queue them again. For now the function is not used, it's just added separately for easier tracking.		2024-07-29 09:27:01 +02:00
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haproxy	MINOR: queue: add a function to check for TOCTOU after queueing	2024-07-29 09:27:01 +02:00
import	MAJOR: import: update mt_list to support exponential back-off (try #2)	2024-07-09 16:46:38 +02:00
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