This topic applies only on the z/OS operating system.

Timer overview

Timers define a limit to the amount of time that is required for a specific operation to complete. The type of operation a timer controls determines when the time period, that is set for that timer, starts to elapse.

Most timers have a default value that defines a reasonable time period, during which a particular operation should complete. When the time limit specified for the timer elapses, the product takes one of the following actions:
  • Sends a minor code to the client if the time limit elapses before the client request is dispatched to a servant.
  • Abnormally ends the servant with an EC3 ABEND if the time limit elapses while the client request is being processed by an application component running in the servant.

    In this situation all of the threads in this servant are terminated. The servant is also terminated to prevent the application from holding resources, and thereby preventing other requests from using these resources. After the servant is terminated, workload management (WLM) starts a new servant to take the place of the servant that was terminated.

    Avoid trouble: The total transaction lifetime timeout and the maximum transaction timeout have grace periods beyond the timeout value specified of approximately four minutes. This extended time period must elapse before an ABEND occurs. gotcha
Different types of timers might reach their time limits simultaneously, because the operations they control might overlap to a certain degree. For example, suppose the application server receives an IIOP client request that is processed by an application component that uses transaction support. In this case, both of the following timers count down simultaneously:
  • control_region_wlm_dispatch_timeout, which limits both the amount of time a client request waits on the WLM queue, as well as the time required for the application component to process the request
  • transaction_defaultTimeout, which limits the amount of time the controller waits for a transaction to be either committed or rolled back

These timers overlap only for the time during which the transaction is processed. To determine which timer cause the error, you can use the symptoms- specific minor codes or EC3 abend reason codes.

To determine the occurrence of a timeout as quickly as possible and to prevent further resource locking, WebSphere Application Server prevents further transactional work on the transactional path where the timeout condition has taken place. This applies equally to attempting to perform work under the current transaction context and to attempting to perform work under a different transactional context.

The timers that are used to control processing behavior can be classified into five general types. These general types, and the operations that they control, are summarized in the following table.

General type Timer processing Timeout symptoms
Input Input timers define limits for receiving a complete request; the countdown starts when a connection to the J2EE server is established. The communication protocol (HTTP, HTTPS) determines the timer used for the request. The session is closed.
Session Session timers define limits for the use of session connections. These timers start the countdown as soon as a session becomes idle. The session is closed.
WLM dispatch Dispatch timers control how long a complete client request waits to be dispatched in a servant region for processing. The countdown starts when the controller places the request on the WLM queue. Depending on the specific timer, the time limit can include not only wait time on the WLM queue, but also the time required for processing a response to the client request. Message BBOO0232W and an EC3 ABEND in the servant (region), with one of these accompanying reason codes:
  • 04130003
  • 04130004
  • 04130006
Transaction Transaction timers define how long:
  • An application or controller waits for one transaction to complete. The countdown starts when the container starts a transaction on behalf of the application component.
  • A controller attempts to recover in-doubt transactions during peer restart and recovery mode.
  • Message BBOT0003W or BBOO0232W
  • An EC3 ABEND in the servant (region), with one of these accompanying reason codes:
    • 04130002
    • 04130005
Output Output timers define how long a controller waits to receive output for a client request. The countdown starts when the client request is dispatched to the servant region for processing. The communication protocol (HTTP or HTTPS) determines the timer used for the request. Message BBOO0232W and an EC3 ABEND in the servant (region), with reason code 04130007



Related tasks
Troubleshooting administration
Related reference
Guidelines for analyzing diagnostic data for timeout conditions
Timeout conditions - possible causes and fixes
Guidelines for altering timeout values
Timeout properties summary
Reference topic    

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Last updated: Aug 29, 2010 10:43:27 PM CDT
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