KB17542: After purging all report caches, users are still able to view History List messages in MicroStrategy Web 8.x

SYMPTOM:
When a report is sent to a user's History List, a cache of type 'matching-history' is created on the Strategy Intelligence Server 8.x. When the History List message is read, this cache is used to retrieve the data. When all report caches are purged, History List messages are not removed but all of the associated cache files they retrieve from are delete. This means that users should encounter an error when requesting History List messages.
 
However, consider the following scenario:
 

• Send a report to history via Strategy Desktop 8.x or Strategy Web 8.x, as shown below:
  

• A Matching-History cache is created for this report and can be seen in the cache monitor in Strategy Desktop 8.x.
• Login to Strategy Web 8.x and request the History List message. The History List message is retrieved from the Matching-History cache created; an XML cache is also created for this report.
• While still logged into Strategy Web 8.x with the same web session, purge all of the report caches using a Strategy Administrator - Command Manager 8.x script or via the Project Configuration Editor in Strategy Desktop 8.x, as shown below:
  

• All report caches, even caches associated with History List messages are deleted. This can be verified by viewing the Cache Monitor in Strategy Desktop 8.x; even the XML caches created are deleted, as shown below:
  

• From the still open and active Strategy Web 8.x session, navigate to the History List page and try to access the History List message from step three. The message will display exactly as it did before even though there is no longer a cache file to retrieve the data from. This is unexpected behavior as the History List message should report that the results for the report are no longer available, as shown below:
  

CAUSE:
The History List message still reports data even after the purge because the data is still available in memory for the working set for the web session. Since the History List message was accessed once in a web session, that page is stored in the working set memory until either the web session is closed (when the user logs out or closes the web browser), the page is overwritten by more user activity in the same web session, or the working set memory is cleared by an restart of the Strategy Intelligence Server 8.x.
 
ACTION:
There is no way to clear the working set memory except to restart the Strategy Intelligence Server 8.x or log the user off the web session. When the user logs out of the web session, they will receive a new clean working set the next time they log in which will correctly inform them that the data is not available for the History List message, as shown below:
 

 
Job Expired
The results for this report are no longer available. Please submit the request again.