Reclaim GcGem slow performance
Under certain conditions, the Reclaim GcGem will stop reclaiming pages in a given transaction until the time limit specified in GcUser UserGlobals parameter #maxTransactionDuration is crossed, where the work accomplished before the stop will be committed and reclaim can continue. But note that the pattern may then repeat, with some pages reclaimed before stopping until #maxTransactionDuration is again crossed and the prior work committed.
This bug can be detected in statmonitor data by noting that commits from the Reclaim GcGem occur in #maxTransactionDuration steps.
Workaround
Reduce the setting of #maxTransactionDuration to improve throughput. It is generally safe to reduce this to 60 seconds. Further reductions are possible, but setting too low may also impact reclaim performance.
Last updated: 12/14/15