Bug 42295 - [Regression] Premature exit of AutoResetEvent.WaitOne(timeoutInMs)
Summary: [Regression] Premature exit of AutoResetEvent.WaitOne(timeoutInMs)
Status: RESOLVED DUPLICATE of bug 42688
Alias: None
Product: Runtime
Classification: Mono
Component: io-layer ()
Version: 4.4.0 (C7)
Hardware: PC Linux
: --- normal
Target Milestone: 4.6.0 (C8)
Assignee: Ludovic Henry
Depends on:
Reported: 2016-06-30 23:06 UTC by mamo
Modified: 2016-07-22 22:01 UTC (History)
6 users (show)

Is this bug a regression?: Yes
Last known good build:

timeout script (428 bytes, text/plain)
2016-06-30 23:06 UTC, mamo

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Description mamo 2016-06-30 23:06:50 UTC
Created attachment 16538 [details]
timeout script

We found that the AutoReset.WaitOne(timeoutInMs) is exiting prematurely in our code with 4.4.1 and not blocking for the entire timeout duration.

We are running mono version:
mono --version
Mono JIT compiler version 4.4.1 (Nightly Thu Jun 30 06:24:08 PDT 2016)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
        TLS:           __thread
        SIGSEGV:       altstack
        Notifications: epoll
        Architecture:  amd64
        Disabled:      none
        Misc:          softdebug
        LLVM:          supported, not enabled.
        GC:            sgen

Using IronPython, below is a test script that exhibits the problem.  Notice that the first call to Timeout(2) blocks for 2min.  But the second call Timeout(30), which should block for 30 min, only blocks for 1min 22sec.

>>> import System
>>> import System.Threading
>>> from System.Threading import *
>>> from System import DateTime
>>> def Timeout(numMinutes):
...     event = AutoResetEvent(False)
...     start = DateTime.Now
...     print "Waiting..." + start.ToString()
...     event.WaitOne(numMinutes * 60 * 1000)
...     finished = DateTime.Now
...     diff = finished - start
...     print "Finished at: " + finished.ToString() + " Elapsed: " + diff.ToString()
>>> Timeout(2)
Waiting...6/30/2016 8:36:39 AM
Finished at: 6/30/2016 8:38:39 AM Elapsed: 00:02:00.0011030
>>> Timeout(30)
Waiting...6/30/2016 8:39:41 AM
Finished at: 6/30/2016 8:41:03 AM Elapsed: 00:01:22.0137040
Comment 1 David Evans 2016-07-01 04:19:08 UTC
We also reproduced the problem on today, btw.
Comment 2 David Evans 2016-07-01 04:20:09 UTC
Problem does not occur on which is what we're running on regularly now. I don't believe i've seen it when testing against though I'm not 100% sure of that.
Comment 3 Łukasz Domeradzki 2016-07-06 03:38:58 UTC
This is the same as https://bugzilla.xamarin.com/show_bug.cgi?id=41701 - no need for duplicate.
Comment 4 Ludovic Henry 2016-07-22 22:01:17 UTC

*** This bug has been marked as a duplicate of bug 42688 ***