What is the exact function and results behind the ‘Expire App Server Cache’? Is it like clearing cache without restarting the app server?

6 Comments »

  1. Admin said,

    June 22, 2016 @ 12:59 pm

    This feature updates a table in the database which informs any psappsrv or process scheduler attached to that database that objects are to be re-cached on their next use. This does not physically clear cache, but has the same effect.

    Note that the object being migrated will always be re-cached on their next use by the psappsrv or process scheduler. This feature goes deeper to force ALL objects to be re-cached.

    There is role-based permission to control who can use this feature. There is also a master switch in the domain setup to turn the feature off, if you want it to be completely unavailable.

  2. CPA said,

    January 11, 2017 @ 12:19 pm

    Can you please elaborate more on this? (without referring us to Oracle support for cache clearing issues). Please focus on what Phire does and helps with.
    We use Phire for most of our migrations, from development to test, to user acceptance to production. In production we have multiple application servers and multiple process schedulers.
    It has been a known PeopleTools issue for quite a few years that certain type of object (may not be clearly defined) migrations (without clearing cache) will cause the cache to get out of sync/corrupted and users start getting various kinds of online errors right after such migrations, forcing Admins to perform a total cache clear on all app servers and possibly all prcs schedulers and/or other actions.
    So the statement that “object being migrated will always be re-cached on their next use by the app server or prcs sched” does not seem to be accurate, because of the above mentioned issue.
    Is the “Expire App Server Cache” feature intended to solve this problem?
    Is the table being updated by this feature, at the object level, or the object type level (pslock/psversion)? and does not cause all cache needed to be cleared.
    Has this feature been implemented in environments with more than 10 or 15 applications servers, such that cache is automatically re-loaded for only the migrated objects?
    Obviously, we would like to be able to migrate from dev all the way to production w/o having to do total cache clearing, but allowing the tools rebuild it as needed; and so the reason for this question is to find out if this would solve the known PeopleTools cache clearing need when migrating projects.

  3. Admin said,

    April 28, 2017 @ 3:09 pm

    Generally speaking, what we stated is true that the objects being migrated will get re-cached automatically by the app servers and process schedulers (whether it’s one or many servers). That is because the VERSION numbers are being updated in PSLOCK/PSVERSION, as they are when using App Designer to move objects.

    However, in some cases the re-caching doesn’t happen smoothly. Sometimes it’s due to the version number updates not working properly. In other cases, it’s due to the app server not managing cache properly. Both scenarios have been reported over the years whether migrating with App Designer or Phire. We continually make enhancements to our application to keep pace with PeopleTools changes and react to bug reports, so if you have predictable and repeatable situations where migrations cause cache issues then please bring them to us in support (support@phire-soft.com) so they can be analyzed and understood.

    The “expire cache” option in Phire, as we explained earlier in this thread, updates the database table PSSTATUS with a new date time stamp. In theory that will force the app servers to re-cache all objects, not just those that were migrated. The effect is for it to assume that the entire cache is invalid and refresh each object from the database upon next reference. This was not really intended to overcome cache issues. In fact, we’ve been deprecating this feature because of confusion about what it does/doesn’t do, and also because of uncertainty with how the app servers behave in the different PeopleTools version or in different configurations.

    If you have any further questions please do contact us in support to discuss your particular situation. (support@phire-soft.com)

  4. CPA said,

    January 11, 2017 @ 2:51 pm

    Forgot to mention or ask if what you do is updating the table psstatus.

  5. Admin said,

    April 28, 2017 @ 12:11 pm

    Sorry for the delay in responding. Yes, that is an update to the PSSTATUS table, setting the LASTCHANGEDTTM to the current date/time.

  6. Admin said,

    August 8, 2018 @ 11:42 am

    Here is an update regarding this feature. In recent releases of Phire we began deprecating this feature because of confusion that it causes. We have also noted concerns that it may lead to caching issues in the target databases depending on how cache management is setup in the psappsrv.

    So new installation are configured with this feature hidden, but can be turned on in the Domain Setup (see the flag labeled: “Enable Expire App Server Cache”). To prevent this feature from being used in your installation, just uncheck that option in the Domain setup and it will be completely hidden.

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