Understanding passivation and requestor timeouts

Passivation details can be saved either as disk files on each Process Commander server, or as database rows in the PegaRULES database. Which option you choose affects which passivation features are possible.

File System

By default, passivation details are saved as files on each Process Commander server. This corresponds to the following prconfig.xml file setting:

<env name="initialization/persistrequestor/storage"
  value="file system" />

The saved information is converted to Java serialization file (SER file type) in a directory named PassivationData, a subdirectory of the temporary files directory. For performance reasons, files are distributed in up to 36 subdirectories of this directory.

On a large system, ensure that adequate disk space is available for these files. Optionally, you can use tactics such as disk striping and RAID over multiple disks for maximum performance. Through a symbolic link, you can place this directory on a dedicated high-performance disk or disk array.

PegaRULES database

In releases before V5.5, passivation details are saved in the PegaRULES database. This is no longer the default for V5.5+.

To save passivation details in the database rather than the server file system, add the following setting to the prconfig.xml file.

<env name="initialization/persistrequestor/storage" value="database" />

When this option is set, the passivation daemon saves requestor information as an instance of the System-Requestor-Context class, corresponding to the pr_sys_context database table. The daemon saves page details as an instance of the System-SavedPages class in the pr_page_store database table.

To recover database space, the system automatically purges pages saved through this mechanism after three days.

When a requestor creates a page but does not access it for a long period, the passivation daemon may passivate the page class, and remove it from the clipboard. Other pages for that requestor remain in memory; requestor processing can continue normally until that page is needed (for read access or for update). On demand, the page is reactivated into memory.

Similarly, when an entire Thread or requestor is inactive, the Thread context or requestor context can be passivated (including the associated clipboard pages).

By default, the passivation daemon passivates:

• Pages that are idle for at least 15 minutes
• Threads that are idle for at least 30 minutes, and
• Requestors that are idle for at least 60 minutes

Typically, page passivation improves performance for production systems that may have 50 or more simultaneously connected requestors (not counting agents). For smaller systems (with adequate JVM memory), the benefits may be small or nil.

To disable page passivation, add the following element to the prconfig.xml file:

<env "initialization/persistrequestor/usepagelevelpassivation" value="false" />

When enabled (through Initialization/PersistRequestor settings in the prconfig.xml file), each HTTP requestor session can be saved after a specific time period of no activity.

To enable timeout passivation, use the following prconfig.xml setting:

<env name="Initialization/PersistRequestor" value="OnTimeout"/>

To prevent timeout passivation, use the Never value:

<env name="Initialization/PersistRequestor" value="Never"/>

If the PersistRequestor element is not present, the system assumes OnTimeout.

Reauthentication

Ordinarily, users are challenged to resubmit username and password credentials after resuming a timed-out, persisted requestor session. You can eliminate this challenge through a prconfig.xml setting:

<env name="Initialization/NoAuthenticateOnActivate" value="true" />

The default value is false.

In a multinode cluster (with appropriate configuration), such requestor passivation can promote high availability and load balancing across nodes, since the reactivated session can resume on a different node than the node that previously supported the user. (The previous node may be down or very busy.)

To support this capability, add the following elements to the prconfig.xml file:

<env name="initialization/persistrequestor/storage" value="database" />

<env name="Initialization/PersistRequestor" value="AtInteractionEnd"/>

The system saves requestor state and user pages into the PegaRULES database at the end of each user interaction. This provides potentially higher availability, but with greater overhead.

HTTP passivation is possible only when passivation details are saved to the PegaRULES database, rather than the file system.

Each user interaction with the browser may involve multiple HTTP messages and responses from the server. To minimize overhead, the passivation daemon attempts to passivate only after the final HTTP response in a series..

Clipboard pages that remain unused for long periods may indicate a design or implementation flaw that can hurt performance; the application created a page but neglected to use the Page-Remove method to remove the page after it was no longer needed.

When building or testing an application, you can discover whether your own processing has created such "orphan" or "near-orphan" page:

1. Select Tools > Clipboard to start the Clipboard tool.
2. From the Action menu in the right panel, select Analyze Clipboard.
3. In the resulting grid of data, look in the Est Size (KB), Last Passivation, and Last Activation columns to identify any pages that were automatically passivated but never reactivated.
4. Research whether such pages are needed at all, and whether they can be removed at specific points in the application, to reduce clipboard size.

To see a list of passivated requestors on the PegaRULES database, open and run the standard list view report System-Requestor-Context.RequestorContextList.ALL. This information is also available from the System Management Application:

1. Select Tools > System Management Application to start the System Management Application.
2. Select a server node.
3. Select Advanced > Passivation Management. The 100 most recently passivated requestors appear at the bottom on the right panel.

When a user exits a requestor session by logging off, all user clipboard pages are erased, including any not saved to the PegaRULES database by the Obj-Save method and Commit method are erased. No passivation occurs.

Agent requestors have a BATCH requestor type. They are never passivated.

V4.2 includes an additional PersistRequestor value UseHTTPSession. This setting is not functional in V5.X.