[Issue 20680] core.thread.Thread leaks OS handle when not joined

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20680

Sebastiaan Koppe <mail at skoppe.eu> changed:

           What    |Removed                     |Added
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                 CC|                            |mail at skoppe.eu
                 OS|Windows                     |All

--- Comment #1 from Sebastiaan Koppe <mail at skoppe.eu> ---
This is the case as well under Linux.

With GDB attached I have put a breakpoint at the core.thread.osthread.Thread's
destructor and confirmed it doesn't get run (I spawned 100k threads and let
them run till finish).

As a workaround I am calling `pthread_detach(pthread_self);` right before the
thread terminates. This is not a good solution though since the Thread's
destructor (if it did ran), would also call pthread_detach, which results in
undefined behaviour.

Better would be to do a thread_detachThis as well, since that will cause a
different branch in the Thread's destructor and avoid the call to
pthread_detach.

Sadly, using thread_detachThis and the pthread_detach I get spurious crashes in
std.concurrency's tls module teardown (sometimes).

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