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Cap worker-lock retry interval to fix int-str overflow crash (fixes #19315 #18221) #19726

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Cap worker-lock retry interval to fix int-str overflow crash (fixes #19315 #18221) #19726

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cap worker-lock retry interval at 10 minutes to avoid unbounded int g…
George3d6 Apr 24, 2026
835dc78
added changelog
George3d6 Apr 24, 2026
a9b504b
proper changelog name
George3d6 Apr 24, 2026
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17 changes: 9 additions & 8 deletions synapse/handlers/worker_lock.py
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Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,7 @@


logger = logging.getLogger(__name__)
_LOCK_RETRY_CAP_SECS = Duration(minutes=10).as_secs()
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@MadLittleMods MadLittleMods Apr 24, 2026

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There is already a PR to address this kind of thing: #19394

🤔 I think we can continue with the other PR which is a bit more fleshed out and is currently stuck at the stage of the review being addressed.


# This lock is used to avoid creating an event while we are purging the room.
# We take a read lock when creating an event, and a write one when purging a room.
Expand Down Expand Up @@ -274,11 +275,11 @@ async def __aexit__(
return r

def _get_next_retry_interval(self) -> float:
next = self._retry_interval
self._retry_interval = max(5, next * 2)
if self._retry_interval > Duration(minutes=10).as_secs(): # >7 iterations
prev = self._retry_interval
self._retry_interval = min(_LOCK_RETRY_CAP_SECS, max(5, prev * 2))
if self._retry_interval == _LOCK_RETRY_CAP_SECS and prev < _LOCK_RETRY_CAP_SECS:
logger.warning(
"Lock timeout is getting excessive: %ss. There may be a deadlock.",
"Lock timeout hit cap of %ss. There may be a deadlock.",
self._retry_interval,
)
return next * random.uniform(0.9, 1.1)
Expand Down Expand Up @@ -361,11 +362,11 @@ async def __aexit__(
return r

def _get_next_retry_interval(self) -> float:
next = self._retry_interval
self._retry_interval = max(5, next * 2)
if self._retry_interval > Duration(minutes=10).as_secs(): # >7 iterations
prev = self._retry_interval
self._retry_interval = min(_LOCK_RETRY_CAP_SECS, max(5, prev * 2))
if self._retry_interval == _LOCK_RETRY_CAP_SECS and prev < _LOCK_RETRY_CAP_SECS:
logger.warning(
"Lock timeout is getting excessive: %ss. There may be a deadlock.",
"Lock timeout hit cap of %ss. There may be a deadlock.",
self._retry_interval,
)
return next * random.uniform(0.9, 1.1)