Signals during MQI calls

 

MQI functions do not return the code EINTR or any equivalent to application programs. If a signal occurs during an MQI call, and the handler calls return, the call continues to run as if the signal had not happened. In particular, MQGET cannot be interrupted by a signal to return control immediately to the application. If you want to break out of an MQGET, set the queue to GET_DISABLED; alternatively, use a loop around a call to MQGET with a finite time expiry (MQGMO_WAIT with gmo.WaitInterval set), and use your signal handler (in a nonthreaded environment) or equivalent function in a threaded environment to set a flag which breaks the loop.

In the AIX environment, WebSphere MQ requires that system calls interrupted by signals are restarted. When establishing your own signal handler with sigaction(2), set the SA_RESTART flag in the sa_flags field of the new action structure otherwise WebSphere MQ might be unable to complete any call interrupted by a signal.

 

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Additional considerations

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