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This is an automatically generated e-mail. To reply, visit:
<a href="https://git.reviewboard.kde.org/r/121134/">https://git.reviewboard.kde.org/r/121134/</a>
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<p style="margin-top: 0;">On November 16th, 2014, 3:58 p.m. CET, <b>Milian Wolff</b> wrote:</p>
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<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">as I said before: Did you check whether that is actually the case? Did you add some assertions to see what other thread is calling this code?</p>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">I'm not sure whether this is supposed to be threadsafe or not. If it must be threadsafe, you'll also need to make s_allowQuit threadsafe (QAtomicBool).</p></pre>
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<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">I have indeed looked at this aspect, but not exhaustively and haven't found evidence of cross-thread reference counting. Yet.
It's unclear what you mean with "that" (the thing actually the case). It "that" refers to the quitting issue, I can of course never prove that it is due to a reference counting race condition because the issue isn't reproducible reliably. I can only invalidate the idea that it is due to such a race condition, whenever it happens again with properly protected reference counting.</p>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">I think we have to leave it up to the kdelibs maintainers/authors to decide whether or not this has to be thread safe. The doxygen documentation for KJob does not mention anything about thread safety. It does however note that <em style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: normal;">KJob and its subclasses is meant to be used in a fire-and-forget way. It's deleting itself when it has finished using deleteLater() so the job instance disappears after the next event loop run.</em> . It is not said that a KJob cannot use a KJob itself, which could lead to concurrent reference (de)counting, nor whether a KJob instance is guaranteed to be deleted in the same thread it was created, and I think that a <em style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: normal;">concurrent processing</em> class that does not explicitly mention it does thread unsafe things can be assumed to be thread safe.</p>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">There's no QAtomicBool, btw.</p></pre>
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<p>- René J.V.</p>
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<p>On November 16th, 2014, 3:12 p.m. CET, René J.V. Bertin wrote:</p>
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<div>Review request for KDE Software on Mac OS X and kdelibs.</div>
<div>By René J.V. Bertin.</div>
<p style="color: grey;"><i>Updated Nov. 16, 2014, 3:12 p.m.</i></p>
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<b style="color: #575012; font-size: 10pt;">Repository: </b>
kdelibs
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<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
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<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">I have been experiencing unexpected exits from KDevelop that were not due to any kind of error in the KDevelop code; it was as if someone told the application to exit normally. This happens mostly on OS X, but also sometimes on Linux.
I finally traced this to <code style="text-rendering: inherit;color: #4444cc;padding: 0;white-space: normal;margin: 0;line-height: inherit;">KGlobal::deref</code> reaching a zero reference count and invoking <code style="text-rendering: inherit;color: #4444cc;padding: 0;white-space: normal;margin: 0;line-height: inherit;">QCoreApplication::quit</code> when called from one of KDevelop's KJob dtors. There does not appear to be a reference counting mismatch in the code, so the issue might be due to a race condition in KGlobal::ref/deref.</p>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">This patch introduces thread-safety to KGlobal's reference counting by turning the simple global <code style="text-rendering: inherit;color: #4444cc;padding: 0;white-space: normal;margin: 0;line-height: inherit;">static int s_refCount</code> into a <code style="text-rendering: inherit;color: #4444cc;padding: 0;white-space: normal;margin: 0;line-height: inherit;">static QAtomicInt s_refCount</code>. I consider this an important bug fix regardless of whether it corrects the issue I have with KDevelop.</p></pre>
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<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Testing </h1>
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<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">On OS X 10.6.8 only for now.</p></pre>
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<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
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<li>kdecore/kernel/kglobal.cpp <span style="color: grey">(cf003a4)</span></li>
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<p><a href="https://git.reviewboard.kde.org/r/121134/diff/" style="margin-left: 3em;">View Diff</a></p>
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