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*** ../pwlib/src/ptlib/unix/tlibthrd.cxx.orig Thu Nov 16 11:14:48 2000
--- ../pwlib/src/ptlib/unix/tlibthrd.cxx Thu Nov 16 11:15:21 2000
*************** void PThread::PX_NewThread(BOOL startSus
*** 386,391 ****
--- 386,409 ----
// pthread_attr_t threadAttr;
// pthread_attr_init(&threadAttr);
PAssertOS(pthread_create(&PX_threadId, NULL, PX_ThreadStart, this) == 0);
+
+ #if defined(P_FREEBSD)
+ // There is a potential race condition here which shows up with FreeBSD 4.2
+ // and later, but really applies to all pthread libraries.
+ // If a thread is started in suspend mode, we need to make sure
+ // the thread (PX_ThreadStart) has had a chance to execute and block on the
+ // sigwait() (blocking on the Resume Signal) before this function returns.
+ // Otherwise the main program may issue a Resume Signal on the thread
+ // by calling PThread::Resume() before the thread is ready for it.
+ // If that happens the program will abort with an unhandled signal error.
+ // A workaround (not 100% guaranteed) is to yield here, which gives
+ // the newly created thread (PX_ThreadStart) a chance to execute.
+
+ if (startSuspended) {
+ sched_yield();
+ }
+ #endif
+
}
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