Service bulletin 212: Potential system outage from a deadlock condition during IBM MQ processing

When an application ECB issues an MQPUT or MQGET API for an IBM MQ queue, a CORHC API is issued to hold a resource for the target IBM MQ queue. The problem occurs if the application ECB is running in a transaction scope and ends abnormally; for example, if a 000010 (CTL-10) system error occurs while the z/TPF system is processing an MQGET or MQPUT API. When an ECB exits, a separate ECB is created to perform a transaction rollback on behalf of the exiting application ECB. If the application ECB is still holding the CORHC resource on the IBM MQ queue, a deadlock condition can occur. The deadlock occurs because the ECB that is created to roll back the transaction scope tries to obtain the CORHC resource on the same IBM MQ queue. The resulting deadlock condition prevents IBM MQ checkpoint from completing, which causes the recovery log to fill and results in a 00C117 (OPR-00C117) catastrophic system error.

APAR PJ47264 resolves this issue.

Note: The issue affects both 31-bit and 64-bit IBM MQ queues and has existed since z/TPF 1.1 was initially released.

For more information, see the PJ47264 APEDIT.