diff options
Diffstat (limited to 'synapse')
| -rw-r--r-- | synapse/util/async.py | 24 |
1 files changed, 22 insertions, 2 deletions
diff --git a/synapse/util/async.py b/synapse/util/async.py index bb252f75d7..0fd5b42523 100644 --- a/synapse/util/async.py +++ b/synapse/util/async.py @@ -203,7 +203,26 @@ class Linearizer(object): except: logger.exception("Unexpected exception in Linearizer") - logger.info("Acquired linearizer lock %r for key %r", self.name, key) + logger.info("Acquired linearizer lock %r for key %r", self.name, + key) + + # if the code holding the lock completes synchronously, then it + # will recursively run the next claimant on the list. That can + # relatively rapidly lead to stack exhaustion. This is essentially + # the same problem as http://twistedmatrix.com/trac/ticket/9304. + # + # In order to break the cycle, we add a cheeky sleep(0) here to + # ensure that we fall back to the reactor between each iteration. + # + # (There's no particular need for it to happen before we return + # the context manager, but it needs to happen while we hold the + # lock, and the context manager's exit code must be synchronous, + # so actually this is the only sensible place. + yield run_on_reactor() + + else: + logger.info("Acquired uncontended linearizer lock %r for key %r", + self.name, key) @contextmanager def _ctx_manager(): @@ -211,7 +230,8 @@ class Linearizer(object): yield finally: logger.info("Releasing linearizer lock %r for key %r", self.name, key) - new_defer.callback(None) + with PreserveLoggingContext(): + new_defer.callback(None) current_d = self.key_to_defer.get(key) if current_d is new_defer: self.key_to_defer.pop(key, None) |