MDEV-20206 : Crash inside timer_callback()[threadpool_win.cc:419]

The most likely cause of the crash is that a timer fired, after it was closed.

MSDN documents such a possibility, in the documentation for
CloseThreadpoolTimer() function, and recommends disabling the timer before
calling WaitForThreadpoolTimerCallbacks()/CloseThreadpoolTimer().

The fix follows this recommendation.

Note, that 5.5-10.1 disabled the timer before close, but this code
was lost in threadpool refactoring in 10.2

1 files changed, 1 insertions, 0 deletions

diff --git a/sql/threadpool_win.cc b/sql/threadpool_win.cc
index 10d6e96b22f..1e2084b9c07 100644
--- a/sql/threadpool_win.cc
+++ b/sql/threadpool_win.cc
@@ -308,6 +308,7 @@ TP_connection_win::~TP_connection_win()
 
   if (timer)
   {
+    SetThreadpoolTimer(timer, 0, 0, 0);
     WaitForThreadpoolTimerCallbacks(timer, TRUE);
     CloseThreadpoolTimer(timer);
   }