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<p>Recently added ThreadPoolExecutor limits number of worker threads to number of logical processors.<br>
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<p>This might cause deadlock in case one's doing nested calls to parallel_for_each, like this:<br>
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<p><br>
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<p>void Bar() { ... <span style="font-size: 12pt;">}</span></p>
<p><br>
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<p>void Foo() {<br>
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<p> parallel_for_each(Begin, End, Bar);<br>
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<p>}</p>
<p><br>
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<p>void main() {<br>
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<p> parallel_for_each(Begin, End, Foo);<br>
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<p>}<br>
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<p><br>
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<p>This happens because both parallel_for_each and parallel_for_each_n wait for task group to finish<br>
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<p>and this may actually never happen in case they're executed from worker threads. In such case worker</p>
<p>thread is blocked in TaskGroup destructor. This does happen <span style="font-size: 12pt;">in lld, when it writes output sections as </span></p>
<p><span style="font-size: 12pt;">th</span><span style="font-size: 12pt;">ere is a nested call to parallel_for_each_n to write each </span><span style="font-size: 12pt;">output section inputs.</span><span style="font-size: 12pt;"> </span></p>
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