IBM Support

Stubs run slowly and require a lot of memory

Technote (troubleshooting)


IBM Rational Test Workbench stubs have poor performance.


The stub shows one of the following symptoms:

  • The processing of messages is very slow, especially large messages.
  • High memory consumption.
  • Process hang.


The stub is producing too much logging information to its console. By default the logging level is set to "Debug". This can result in excessive CPU usage, because the logging requires processing. It can also result in high memory usage, because memory retains console output.

For a stub that runs inside Rational Integration Tester (RIT) all console output from tests and stubs is retained in memory. This includes all message data. With this data the user can display messages in the Message Difference window. For multiple large messages, this can result in all of the process memory being consumed.

Resolving the problem


Reduce the logging and reduce the amount of messages that are retained in the consoles.

Reduce the Logging level

  1. Open the stub in Test Factory.

  2. Click Logging.

  3. Click the drop-down and select Normal.

  4. Save the stub.

Reduce the messages retained in memory

  1. Exit from RIT.

  2. Start Library Manager and add the following entry to JVM Arguments on its own line.

    -Dcom.ghc.ghTester.gui.console.trim=true (trims to 300000 characters)

    or specify the character limit

    -Dcom.ghc.ghTester.gui.console.trim=5000 (trims to 5000 characters)

    Note: Limiting the console output might prevent you from using the Message Difference window to view and edit messages that have been sent and received.

  3. Click OK to save and exit Library Manager.

  4. Start RIT.


Console output is not retained in memory when running a stub on an Agent so there is no need to trim the output. The single change here is to reduce the logging level.

There are two ways to do this.
  • Change the logging level in RIT as detailed above and republish and re-start the stub.

  • Re-start the existing stub in Rational Test Control Panel with reduced logging as follows.

  1. Log in to the Rational Test Control Panel.

  2. Go to the VIE page and locate the stub.

  3. Click Start stub.

  4. Click Configuration.

  5. Click Logging.

  6. Click the Normal radio button.

  7. Click Start stub.

  • See the IBM Rational Integration Tester Reference Guide for full details of stub configuration. This includes information on how to increase Worker threads for improved throughput.
  • See the IBM Rational Test Virtualization Server Reference Guide for full details of stub deployment.

Document information

More support for: Rational Test Workbench
Rational Integration Tester

Software version: 8.0

Operating system(s): AIX, Linux, Solaris, Windows

Reference #: 1627742

Modified date: 15 March 2013

Translate this page: