Experimental Physics and
Industrial Control System

Ralph Lange <[email protected]> · Mon, 16 Aug 2010 12:03:10 -0400

Hi Andrew,


it looks as I have found the reason for the segfaults, which I think is

a bug in CAC.



In the cac::~cac() destructor, a private member

"this->iiuExistenceCount" is used to determine if cac should wait for

TCP threads to shutdown. While this counter gets correctly decreased in

cac::destroyIIU(), it never gets increased or set (except initialized to

0 in the cpp constructor).



So cac::~cac() was never waiting for the TCP threads to shutdown, and

happily kept tearing down the timer/mutex infrastructure. If the threads

were not fast enough, they were hitting on destroyed semaphores when

cancelling their watchdog timers - that was causing the exceptions and

segfaults.


This one-line fix will take care of the problem:


=== modified file 'src/ca/cac.cpp'

--- src/ca/cac.cpp      2010-04-15 21:06:16 +0000
+++ src/ca/cac.cpp      2010-08-16 15:24:13 +0000
@@ -287,6 +287,7 @@
             //
             // shutdown all tcp circuits
             //
+            this->iiuExistenceCount = this->circuitList.count();
             tsDLIter < tcpiiu > iter = this->circuitList.firstIter ();
             while ( iter.valid() ) {
                 // this causes a clean shutdown to occur


Maybe it actually takes care of several shutdown related issues...

Yay!
Ralph



Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System