comphelper: fix MSVC hang in ThreadPool::shutdown()

Commit aa68c99d88fd7abe08c4aee5206c859a0cdba38e added some code using
std::condition_variable to comphelper.

Built with MSVC 2017, this causes many cppunittester.exe processes to
deadlock in ThreadPool::shutdown():

    maTasksChanged.notify_all();

This ultimately calls NtReleaseKeyedEvent(), which never returns.

The reason appears to be a bug in Windows 7, for which a "hotfix"[1] is
avaiable here, but it's apparently not distributed via Windows Update
so we likely can't rely on users or even developers having this installed.

However, the documentation of DllMain[2] and ExitProcess[3] indicates
that during shutdown, by the time global destructors are invoked
all threads other than the one that called ExitProcess have already
been terminated.

Returning from main() implicitly calls ExitProcess [4].

As it turns out the problem only happens for some CppUnitTests because
soffice.bin will call ThreadPool::shutdown() from Desktop::doShutdown()
while it is still safe.

[1] http://support.microsoft.com/kb/2582203
[2] https://msdn.microsoft.com/en-US/library/windows/desktop/ms682583(v=vs.85).aspx
[3] https://msdn.microsoft.com/en-us/library/windows/desktop/ms682658(v=vs.85).aspx
[4] https://blogs.msdn.microsoft.com/oldnewthing/20100827-00/?p=13023

Change-Id: I6137461ca7efe9a5fbe4f8f8478fb96de3570469
Reviewed-on: https://gerrit.libreoffice.org/35066
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Stahl <mstahl@redhat.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/unotest/source/python/org/libreoffice/unotest.py b/unotest/source/python/org/libreoffice/unotest.py
index 13b00845bb36..38c6b2266b31 100644
--- a/unotest/source/python/org/libreoffice/unotest.py
+++ b/unotest/source/python/org/libreoffice/unotest.py
@@ -182,6 +182,9 @@ class UnoInProcess:
         global havePonies
         if not(havePonies):
             pyuno.private_initTestEnvironment()
+            # note: this will be called early enough, from Py_Finalize
+            import atexit
+            atexit.register(pyuno.private_initTestEnvironment, False)
             havePonies = True
     def openEmptyWriterDoc(self):
         assert(self.xContext)