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This is an automatically generated e-mail. To reply, visit:
<a href="https://git.reviewboard.kde.org/r/128762/">https://git.reviewboard.kde.org/r/128762/</a>
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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;">Actually ... I think the problem here is in clang, not JS. The JS locking code is inefficient, but not wrong. Calling BackgroundParser::isQueued() or so with the DUChainLock held should be allowed.</p>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">What really causes the deadlocks (https://bugs.kde.org/show_bug.cgi?id=367825, http://blog.svenbrauch.de/2016/06/16/kdevelop-5-0-standalone-executable-for-linux/#comment-529) is that Clang's parsejob constructor acquires a DUChain lock (in translationUnitForURL()). That must not happen, because createParseJob is called from BackgroundParser::parseDocuments(), and that holds the background parser mutex. So clang first acquires the background parser mutex, then the duchain lock; and JS first acquires the duchain lock and then the background parser mutex (by calling isQueued() with the duchain lock held) -> deadlock. The second lock ordering (used by JS and other languages) is far more sensible, because the background parser mutex is needed for much shorter times much less frequently.</p>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">I'll see that I can fix that in clang.</p></pre>
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<p>- Sven Brauch</p>
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<p>On September 1st, 2016, 8:22 p.m. UTC, Sven Brauch wrote:</p>
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<div>Review request for KDevelop and Kevin Funk.</div>
<div>By Sven Brauch.</div>
<p style="color: grey;"><i>Updated Sept. 1, 2016, 8:22 p.m.</i></p>
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<b style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Bugs: </b>
<a href="http://bugs.kde.org/show_bug.cgi?id=367825">367825</a>
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<b style="color: #575012; font-size: 10pt;">Repository: </b>
kdevelop
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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;">We <em style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: normal;">must not</em> hold a duchain lock when contextOfFile() is called. That
might try to add something to the background parser queue, which locks
the background parser mutex; then both locks are held, which causes
deadlocks.</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;">Opened some test project, no crashes, no freezes, and the (I think) reason for the freeze is gone.</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>languages/qmljs/codecompletion/context.cpp <span style="color: grey">(3a44f45)</span></li>
<li>languages/qmljs/codecompletion/tests/test_qmljscompletion.cpp <span style="color: grey">(b689418)</span></li>
<li>languages/qmljs/duchain/declarationbuilder.cpp <span style="color: grey">(fb0cb5d)</span></li>
<li>languages/qmljs/duchain/expressionvisitor.cpp <span style="color: grey">(3b641f5)</span></li>
<li>languages/qmljs/duchain/frameworks/nodejs.cpp <span style="color: grey">(41964e4)</span></li>
<li>languages/qmljs/duchain/helper.cpp <span style="color: grey">(e537103)</span></li>
<li>languages/qmljs/duchain/parsesession.cpp <span style="color: grey">(d1ad4a9)</span></li>
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<p><a href="https://git.reviewboard.kde.org/r/128762/diff/" style="margin-left: 3em;">View Diff</a></p>
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