Sun Java System Message Queue 4.3 Developer's Guide for C Clients

Connection Exceptions

When a connection exception occurs, the Message Queue C library thread that is provided to the connection calls its MQConnectionExceptionListenerFunc callback if one exists. If an MQConnectionExceptionListenerFunc callback is used for multiple connections, it can potentially be called concurrently from different connection threads.

You should not call the MQCloseConnection function in an MQConnectionExceptionListenerFunc callback. Instead the callback function should notify another thread to call MQCloseConnection and return.