handle a possible (unlikely?) deadlock in threadpool cleanup

Change-Id: I4886989816662bad50db145fd1ff1466e8a3a140
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/106700
Tested-by: Jenkins
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/comphelper/source/misc/threadpool.cxx b/comphelper/source/misc/threadpool.cxx
index 3c335e7f4761..4ff7bac3aede 100644
--- a/comphelper/source/misc/threadpool.cxx
+++ b/comphelper/source/misc/threadpool.cxx
@@ -167,7 +167,14 @@ void ThreadPool::shutdownLocked(std::unique_lock<std::mutex>& aGuard)
     else
     {
         while( !maTasks.empty() )
+        {
             maTasksChanged.wait( aGuard );
+            // In the (unlikely but possible?) case pushTask() gets called meanwhile,
+            // its notify_one() call is meant to wake a up a thread and process the task.
+            // But if this code gets woken up instead, it could lead to a deadlock.
+            // Pass on the notification.
+            maTasksChanged.notify_one();
+        }
     }
     assert( maTasks.empty() );