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Rational Functional Tester playback results in "com.rational.test.ft.svs.Mutex$TimeoutException" error

Technote (troubleshooting)


Attempts to run IBM Rational Functional Tester (RFT) scripts result in the error "com.rational.test.ft.svs.Mutex$TimeoutException".


During playback, Rational Functional Tester halts with the following exception and Rational Functional Tester must be restarted:



The default SpyHeapSize is set to low for your environment.

Resolving the problem

The default SpyHeapSize is 1048576.

This value can be increased by adding a DWORD value named SpyHeapSize to the Microsoft registry and set its value to 2097152 decimal.

Note: If setting this value does not resolve the issue, contact Rational support for assistance to perform a root cause analysis for your environment.


This solution contains information about modifying the system registry. Before making any modifications to the Microsoft Registry Editor, it is strongly recommended that you make a backup of the existing registry. For more information describing how to back up the registry, refer to Microsoft Knowledge Base article 256986


  1. Open the Windows Registry Editor (Start > Run and type regedit).

  2. Navigate to [HKEY_LOCAL_MACHINE\SOFTWARE\Rational Software\Rational Test\8]

  3. Create a new DWORD value named SpyHeapSize and set its value data to 2097152 (or 200000 hexadecimal)

Document information

More support for: Rational Functional Tester
Test Execution

Software version: 7.0,,,, 7.0.1,,,, 8.0,,,,, 8.1,,,, 8.1.1,,,, 8.2,,, 8.2.1,, 8.2.2,, 8.3,,, 8.5,, 8.5.1,

Operating system(s): Windows

Reference #: 1318359

Modified date: 29 January 2010