severity changed

boost-bugs@… — Fri, 18 Jul 2014 11:23:06 GMT

severity Showstopper → Problem

Tue, 22 Jul 2014 21:09:12 GMT

We hit this bug and fixed it with the following patch:

--- a/boost/asio/detail/posix_event.hpp
+++ b/boost/asio/detail/posix_event.hpp
@@ -58,8 +58,8 @@ public:
   {
     BOOST_ASIO_ASSERT(lock.locked());
     signalled_ = true;
-    lock.unlock();
     ::pthread_cond_signal(&cond_); // Ignore EINVAL.
+    lock.unlock();
   }
   // Reset the event.

The issue is that in the task_io_service, the thread_info contains an event, and the thread_info lifetime is protected by the mutex associated with the lock passed into signal_and_unlock, so there is a race where the event is destroyed after the lock.unlock() but before the pthread_cond_signal().

The "Ignore EINVAL" comment suggests that someone hit this issue before. Unfortunately, relying on pthread_cond_signal to return an error (and not crash) is not a sufficient solution.

boost-bugs@… — Wed, 23 Jul 2014 13:38:02 GMT

I can confirm that the crash is gone with this change, thanks for posting.

ikostov@… — Thu, 21 Sep 2017 11:18:54 GMT

found similar issues https://svn.boost.org/trac10/ticket/12690. Patch works for me as well

Boost C++ Libraries: Ticket #10213: Reproducible crash with Boost Asio and io_service::post

severity changed