IBM FileNet P8, Version 5.2.1

Queue sweeps

Queue sweeps provide a generic queuing service. They are especially useful in controlling the flow of work to a slow or resource-intensive process. Queue sweeps are optimized for continuous processing of queues.

In the sweep subsystem, items to be processed asynchronously are placed in a queue table. These items, referred to as queue entries, include the necessary information to allow processing by a queue sweep. For example, if you install the Thumbnail Extensions add-on, a queue table is created for thumbnail request entries. An instance of a queue sweep, Thumbnail Request Sweep, is also created. When it is enabled, the sweep runs continuously to process the requests and to generate document thumbnails.

Other queue sweep examples can be found in association with advanced storage areas. If you create an advanced storage area, the server adds queue sweep instances that assist in the operation of the advanced storage area.

In the administration console, queue sweeps are listed in the navigation pane under Sweep Management > Queue Sweeps.

A queue sweep runs at the start time for which it is configured. If a start time is not set, then the sweep is eligible to start immediately. (It will not start immediately if, for example, the sweep is disabled, or if time slots are set to times in the future.) An end time when the sweep stops running can also be configured.

Sweep results

A queue sweep includes counter properties that reflect the results of the sweep. There are properties for the iteration that is currently running and properties for the cumulative total of all of the iterations that previously ran. The following table lists the properties that reflect the current iteration and the total of all of the iterations.

Counter property	Description
Current iteration: CurrentExaminedObjectCount All iterations: ExaminedObjectCount	Number of objects that the queue sweep evaluated but did not necessarily process
Current iteration: CurrentProcessedObjectCount All iterations: ProcessedObjectCount	Number of objects that met the criteria for processing
Current iteration: CurrentFailedObjectCount All iterations: FailedObjectCount	Number of objects that met the criteria for processing but failed to process
Current iteration: CurrentDeferredObjectCount All iterations: DeferredObjectCount	Number of objects for which the processing is deferred.

When a queue entry is processed successfully, the item is removed from the queue. Items that do not process successfully are given a status, as follows:

WAITING - Indicates that the operation did not start on the queue entry.
IN-PROGRESS - Indicates that the operation is in progress.
RETRY-WAIT - Indicates that the operation failed and is being retried on the queue entry. Alternatively, the queue sweep deferred processing on the queue entry because certain conditions are not met, but can be corrected.
FAILED - Indicates that the operation failed on the queue entry and is no longer being retried.

Using the administrator console, you can access queue entries in the RETRY-WAIT or FAILED state. Navigate to the Queue Entries tab of the queue sweep. For more information, see Queue sweep troubleshooting.

Deferred queue entries

A deferred queue entry is one in which a queue sweep determines that the entry cannot currently be processed because of a correctable problem. For example, when an advanced storage area is used, a content deletion request would be deferred if the content is on a storage device that is offline. When the storage device is restored, the request would then process successfully. Deferred entries are scheduled for retry in five minutes.

Failed queue entries

A failed queue entry is one that cannot be processed because of an unexpected problem with the entry. For correctable problems that are fixed, failed queue entries can be retried.

The sweep subsystem sets a failed queue entry to either a FAILED or RETRY-WAIT status, depending on how the MaximumFailures property is set on the queue sweep. This property determines how many times the sweep retries processing a queue entry. For each failure, the sweep subsystem increments the FailureCount property and sets the LastFailureReason property on the queue entry.

If the MaximumFailures property is set to a non-zero value, the queue sweep retries processing until the FailureCount value equals or exceeds the current MaximumFailures value. At that point, the QueueEntryStatus property is set to FAILED and reprocessing is no longer attempted on the queue entry.

If the MaximumFailures property is set to a zero value, there are no maximum processing attempts, and the sweep continuously retries to process a failed queue entry. The QueueEntryStatus property is set to RETRY-WAIT.

If you fix the problem for a queue entry with a RETRY-WAIT status, the queue entry will be successfully processed when it is scheduled for a retry.

If you fix the problem for a queue entry with a FAILED status, you must also reset the entry's FailureCount property to zero before processing restarts. After you reset the FailureCount property to zero, the QueueEntryStatus property is changed from FAILED to RETRY_WAIT.

If you cannot fix the underlying problem of a failed queue entry, you can delete the queue entry.