commit 15bfb0312030a79c1985564dcbf7ee18101388b4
Author: Leonid Evdokimov <l...@darkk.net.ru>
Date: Mon Oct 10 23:06:50 2016 +0300
Fix #612 deadlock confirmed by TestScheduler.test_thundering_herd
The trivial fix makes sense as current SchedulerService ticks every 30
seconds and imprecise scheduling is acceptable.
---
ooni/agent/scheduler.py | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/ooni/agent/scheduler.py b/ooni/agent/scheduler.py
index f6b52b7..969602a 100644
--- a/ooni/agent/scheduler.py
+++ b/ooni/agent/scheduler.py
@@ -61,6 +61,11 @@ class DidNotRun(Exception):
class ScheduledTask(object):
+ """
+ Two ScheduledTask instances with same identifier are not permited to run
+ concurrently. There should be no ScheduledTask queue waiting for the lock
+ as SchedulerService ticks quite often.
+ """
_time_format = "%Y-%m-%dT%H:%M:%SZ"
schedule = None
identifier = None
@@ -117,6 +122,9 @@ class ScheduledTask(object):
@defer.inlineCallbacks
def run(self):
+ if self._last_run_lock.locked:
+ # do not allow the queue to grow forever
+ raise DidNotRun
yield self._last_run_lock.acquire()
if not self.should_run:
self._last_run_lock.release()
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