Implicit syncpoint

IBM MQ Version 9.0.5 adds an implicit syncpoint for persistent messages put outside of syncpoint.

When putting persistent messages, IBM MQ is optimized for putting persistent messages under syncpoint. Multiple applications concurrently putting persistent messages to the same queue typically perform better if those applications use syncpoint. This is because the locking strategy of IBM MQ is more efficient if syncpoint is used when putting persistent messages.

The ImplSyncOpenOutput parameter in the qm.ini file, controls whether an implicit syncpoint can be added when applications put persistent messages outside of syncpoint. This can provide a performance improvement, without applications being aware of the implicit syncpoint.

Implicit syncpoint only provides a performance boost when there are multiple applications concurrently putting to the queue, because it reduces lock contention. ImplSyncOpenOutput specifies the minimum number of applications that have a queue open for output before an implicit syncpoint can be added. The default value is 2. This means, that if we do not explicitly specify ImplSyncOpenOutput, implicit syncpoint is only added if multiple applications are putting to the queue.

If you add an implicit syncpoint, statistics reflect that happening, and you might see a transaction output from runmqsc display conn.

Set ImplSyncOpenOutput=OFF if you never want an implicit syncpoint added.

See Tuning parameters for more information.