<table><tr><td style="">dfaure requested changes to this revision.<br />dfaure added a comment.<br />This revision now requires changes to proceed.
</td><a style="text-decoration: none; padding: 4px 8px; margin: 0 8px 8px; float: right; color: #464C5C; font-weight: bold; border-radius: 3px; background-color: #F7F7F9; background-image: linear-gradient(to bottom,#fff,#f1f0f1); display: inline-block; border: 1px solid rgba(71,87,120,.2);" href="https://phabricator.kde.org/D24752">View Revision</a></tr></table><br /><div><div><p><tt style="background: #ebebeb; font-size: 13px;">slotReport</tt> isn't the only problem, all of the subjob handling etc. seems very racy to me.</p>
<p>I suggest to start from scratch and write the smallest possible worker, whose only job is to delete a list of files, and report progress/completion via signal/slots or invokeMethod.</p></div></div><br /><div><strong>INLINE COMMENTS</strong><div><div style="margin: 6px 0 12px 0;"><div style="border: 1px solid #C7CCD9; border-radius: 3px;"><div style="padding: 0; background: #F7F7F7; border-color: #e3e4e8; border-style: solid; border-width: 0 0 1px 0; margin: 0;"><div style="color: #74777d; background: #eff2f4; padding: 6px 8px; overflow: hidden;"><a style="float: right; text-decoration: none;" href="https://phabricator.kde.org/D24752#inline-140004">View Inline</a><span style="color: #4b4d51; font-weight: bold;">deletejob.cpp:161</span></div>
<div style="font: 11px/15px "Menlo", "Consolas", "Monaco", monospace; white-space: pre-wrap; clear: both; padding: 4px 0; margin: 0;"><div style="padding: 0 8px; margin: 0 4px; background: rgba(251, 175, 175, .7);"> <span class="n">connect</span><span class="p">(</span><span class="n">d_func</span><span class="p">()</span><span style="color: #aa2211">-></span><span class="n">m_reportTimer</span><span class="p">,</span> <span class="bright"></span><span class="n"><span class="bright">SIGNAL</span></span><span class="bright"></span><span class="p"><span class="bright">(</span></span><span class="n">timeout<span class="bright"></span></span><span class="bright"></span><span class="p"><span class="bright">())</span>,</span> <span style="color: #aa4000">this</span><span class="p">,</span> <span class="bright"></span><span class="n"><span class="bright">SLOT</span></span><span class="bright"></span><span class="p"><span class="bright">(</span></span><span class="bright"></span><span class="n"><span class="bright">slotReport</span></span><span class="bright"></span><span class="p"><span class="bright">()));</span></span>
</div><div style="padding: 0 8px; margin: 0 4px; background: rgba(151, 234, 151, .6);"> <span class="n">connect</span><span class="p">(</span><span class="n">d_func</span><span class="p">()</span><span style="color: #aa2211">-></span><span class="n">m_reportTimer</span><span class="p">,</span> <span class="bright"></span><span style="color: #aa2211"><span class="bright">&</span></span><span class="bright"></span><span class="n"><span class="bright">QTimer</span></span><span class="bright"></span><span style="color: #aa2211"><span class="bright">::</span></span><span class="n">timeout</span><span class="p">,</span> <span style="color: #aa4000">this</span><span class="p">,</span> <span class="bright"></span><span class="p"><span class="bright">[</span></span><span class="bright"></span><span style="color: #aa4000"><span class="bright">this</span></span><span class="bright"></span><span class="p"><span class="bright">]</span></span><span class="bright"> </span><span class="p"><span class="bright">()</span></span><span class="bright"> </span><span class="p"><span class="bright">{</span></span>
</div><div style="padding: 0 8px; margin: 0 4px; background: rgba(151, 234, 151, .6);"> <span class="n">d_func</span><span class="p">()</span><span style="color: #aa2211">-></span><span class="n">slotReport</span><span class="p">();</span>
</div><div style="padding: 0 8px; margin: 0 4px; background: rgba(151, 234, 151, .6);"> <span class="p">});</span>
</div></div></div>
<div style="margin: 8px 0; padding: 0 12px;"><p style="padding: 0; margin: 8px;">This calls slotReport in the main thread, where it will read many values from the worker. Those values are written by the worker, from a secondary thread. This is the very definition of a race condition.</p>
<p style="padding: 0; margin: 8px;">I thought the plan (in the task's pseudo-code) was to move into a worker, as little data as possible. And to never access that data from two concurrent threads.</p>
<p style="padding: 0; margin: 8px;">In this patch, almost all of the members are moved to the worker, which creates race conditions all around.</p>
<p style="padding: 0; margin: 8px;">I'm updating my "thread sanitizer" build of Qt and KIO to prove it, but I'm pretty sure :-)</p></div></div><br /><div style="border: 1px solid #C7CCD9; border-radius: 3px;"><div style="padding: 0; background: #F7F7F7; border-color: #e3e4e8; border-style: solid; border-width: 0 0 1px 0; margin: 0;"><div style="color: #74777d; background: #eff2f4; padding: 6px 8px; overflow: hidden;"><a style="float: right; text-decoration: none;" href="https://phabricator.kde.org/D24752#inline-140002">View Inline</a><span style="color: #4b4d51; font-weight: bold;">deletejob.cpp:180</span></div>
<div style="font: 11px/15px "Menlo", "Consolas", "Monaco", monospace; white-space: pre-wrap; clear: both; padding: 4px 0; margin: 0;"><div style="padding: 0 8px; margin: 0 4px; background: rgba(251, 175, 175, .7);"> <span class="bright"></span><span class="n"><span class="bright">statNextSrc</span></span><span class="p">();</span>
</div><div style="padding: 0 8px; margin: 0 4px; background: rgba(151, 234, 151, .6);"> <span class="bright"></span><span class="n"><span class="bright">ownThread</span></span><span class="bright"> </span><span style="color: #aa2211"><span class="bright">=</span></span><span class="bright"> </span><span class="n"><span class="bright">QThread</span></span><span class="bright"></span><span style="color: #aa2211"><span class="bright">::</span></span><span class="bright"></span><span class="n"><span class="bright">currentThread</span></span><span class="p">();</span>
</div><div style="padding: 0 8px; margin: 0 4px; background: rgba(151, 234, 151, .6);"> <span class="n">m_ioThread</span> <span style="color: #aa2211">=</span> <span style="color: #aa4000">new</span> <span class="n">QThread</span><span class="p">();</span>
</div><div style="padding: 0 8px; margin: 0 4px; background: rgba(151, 234, 151, .6);"> <span class="n">ioWorker</span><span class="p">.</span><span class="n">moveToThread</span><span class="p">(</span><span class="n">m_ioThread</span><span class="p">);</span>
</div></div></div>
<div style="margin: 8px 0; padding: 0 12px;"><p style="padding: 0; margin: 8px;">Where is the corresponding <tt style="background: #ebebeb; font-size: 13px;">delete</tt> statement?</p></div></div></div></div></div><br /><div><strong>REPOSITORY</strong><div><div>R241 KIO</div></div></div><br /><div><strong>REVISION DETAIL</strong><div><a href="https://phabricator.kde.org/D24752">https://phabricator.kde.org/D24752</a></div></div><br /><div><strong>To: </strong>meven, dfaure<br /><strong>Cc: </strong>kde-frameworks-devel, LeGast00n, GB_2, michaelh, ngraham, bruns<br /></div>