Re: [Geary] [PATCH] Fix synchronization deadlock in SpinWaiter.wait()

[Jim Nelson <jim yorba org>]

Good catch, Mark.  I've applied your patch to master.  As I mentioned on the ticket, I'm contemplating an 0.8.3 release, and your fix would be a part of that.

-- Jim


On Sun, Nov 30, 2014 at 12:51 PM, Mark R. Pariente <markpariente gmail com> wrote:

The new implementation of g_cond_wait_until() in glib 2.42 uses futex on linux if available which results in a very tight window of time between acquiring the mutex and releasing it. In some systems this window of time is not sufficient for the SpinWaiter.notify() thread to ever acquire the mutex, leading to deadlocks where SpinWaiter.wait() keeps re-acquiring the mutex and endlessly trying cond.wait_until() even though the notify() thread is trying to signal the condition. The "fix" here is to intentionally release the mutex when calling into the PollService callback to give the notify() thread a chance to acquire the mutex. This addresses https://bugzilla.gnome.org/show_bug.cgi?id=737811 which is marked resolved/fixed which at least for my system wasn't fixed yet. --- src/engine/util/util-synchronization.vala | 3 +++ 1 file changed, 3 insertions(+) diff --git a/src/engine/util/util-synchronization.vala b/src/engine/util/util-synchronization.vala index 9416d12..5296b53 100644 --- a/src/engine/util/util-synchronization.vala +++ b/src/engine/util/util-synchronization.vala @@ -64,10 +64,13 @@ public class SpinWaiter : BaseObject { int64 end_time = get_monotonic_time() + (actual_poll_msec * TimeSpan.MILLISECOND); if (!cond.wait_until(mutex, end_time)) { // timeout passed, allow the callback to run + mutex.unlock(); if (!cb()) { // PollService returned false, abort + mutex.lock(); break; } + mutex.lock(); } }

--

2.1.3 --Mark _______________________________________________ geary-list mailing list geary-list gnome org https://mail.gnome.org/mailman/listinfo/geary-list