Fri Feb 14 16:34:46 UTC 2014 Steve Huston <shuston@riverace.com>

        * ace/Dev_Poll_Reactor.cpp (dispatch_io_event): Do not dispatch to
          a handler that is suspended. Prevents multiple callbacks to the
          same handler at the same time when multiple threads are dispatching
          and changing registrations at the same time. Fixes Bugzilla 4129.
          Thank you to Alexey Zubko and Howard Finer for both coming up with
          the same answer independently!

        * THANKS: Added Alexey Zubo to the Hall of Fame.

1 files changed, 6 insertions, 0 deletions

diff --git a/ACE/ace/Dev_Poll_Reactor.cpp b/ACE/ace/Dev_Poll_Reactor.cpp
index adc72f23c1f..739bffd52b3 100644
--- a/ACE/ace/Dev_Poll_Reactor.cpp
+++ b/ACE/ace/Dev_Poll_Reactor.cpp
@@ -1177,6 +1177,12 @@ ACE_Dev_Poll_Reactor::dispatch_io_event (Token_Guard &guard)
         info = this->handler_rep_.find (handle);
         if (info == 0)   // No registered handler any longer
           return 0;
+	// It is possible another thread has changed (and possibly re-armed)
+	// this handle mask before current thread obtained the repo lock.
+	// If that did happen and this handler is still suspended, don't
+	// dispatch on top of another callback. See Bugzilla 4129.
+	if (info->suspended)
+	  return 0;
 
         // Figure out what to do first in order to make it easier to manage
         // the bit twiddling and possible pfds increment before releasing