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7.2.6 Tuning a workload management configuration

7.2.6 Tuning a workload management configuration

The workload management service uses several parameters to control the behavior of the workload management run time. In the majority of cases, you do not need to explicitly set the values of these parameters.  However, if you are experiencing problems with your workload management configuration, you can adjust these properties to tune the behavior of the workload management run time.

Important: Set the values of these properties only in response to problems that you encounter in your environment. If workload management is functioning correctly, changing these properties can produce undesirable results.

Workload management client properties

A workload management client can be a cloned resource or an application server that acts as an EJB client to a cloned resource. The following properties can be used to control the behavior of the workload management client run time. They are set as command-line arguments for the Java Virtual Machine (JVM) process in which the workload management client is running. In many cases, such as where a servlet is a client to an enterprise bean, this means that these parameters are specified as part of the command- line arguments for the application server where the servlet is running.

  • com.ibm.CORBA.requestTimeout. This property specifies the timeout period for responding to workload management requests.  Set this value in the Command Line Arguments field by using the -D option as follows:
    -Dcom.ibm.CORBA.requestTimeout=timeout_interval 

    where timeout_interval is the timeout period in seconds. If your network is subject to extreme latency, specify a large value to prevent timeouts. If you specify a value that is too small, an application server that particpates in workload management can ttime out before it receives a response.

Note: Be very careful when you specify this property: it has no recommended value. Set it only if your application is experiencing problems with timeouts.

  • com.ibm.ejs.wlm.MaxCommFailures. This property specifies the number of attempts that a workload management client makes to contact the administrative server that manages workloads for the client. The workload management client run time does not identify an administrative server as unavailable until a certain number of attempts to access it have failed. This allows workload management to continue if the server suffers from transient errors that can briefly prevent it from communicating with a client. However, it can also propagate nontransient administrative server failures to the client.  Set this value in the Command Line Arguments field in the administrative console by using the -D option as follows:
    -Dcom.ibm.ejs.wlm.MaxCommFailures=max_failures

    where max_failures specifies how many times the client attempts to contact the administrative server after the first failure.  The default value is zero, which means that the workload management run time does not attempt to use the administrative server after the first failure until a timeout interval (specified by the com.ibm.ejs.wlm.UnusableInterval parameter) expires.  This reduces the possibility of further server failures being propagated to the client.

  • com.ibm.ejs.wlm.UnusableInterval. This property specifies the time interval that the workload management client run time waits after it marks an administrative server as unavailable before it attempts to contact the server again. Set this value in the Command Line Arguments field in the administrative console by using the -D option as follows:
    -Dcom.ibm.ejs.wlm.UnusableInterval=interval 

    where interval is the time in seconds between attempts.  The default value is 900 seconds. If this parameter is set to a large value, the server is marked as unavailable for a long period of time. This prevents the workload management refresh protocol from refreshing the workload management state of the client until after this time period has ended.

Administrative server properties

The administrative server for the cloned resources that participate in a workload managment group (such as an application server cluster) acts as the workload management server. 

  • com.ibm.ejs.wlm.RefreshInterval. This property specifies the interval at which the administrative server updates the server group information to the cloned application servers that participate in workload management. It is appended to the arguments for the com.ibm.ejs.sm.util.process.Nanny.adminServerJvmArgs entry in the administrative server configuration file. The value of this property is specified as follows:
    com.ibm.ejs.wlm.RefreshInterval=interval

    where interval is the number of seconds that elapse between the administrative server updates. The default value is 300 seconds.

Go to previous article: Using workload management - a sample procedure Go to next article: Run-time exceptions and failover strategies for workload management

 

 
Go to previous article: Using workload management - a sample procedure Go to next article: Run-time exceptions and failover strategies for workload management