IBM User Guide for Java V7 on Windows > Troubleshooting and support > Problem determination > Windows problem determination > Debugging performance problems
Testing JVM optimizations
Performance problems might be associated with new optimizations that have been introduced for this release.
Java™ monitor optimizations
This release introduces new optimizations that are expected to improve CPU efficiency. However, there might be some situations where lower CPU utilization is achieved, but overall application performance decreases. You can test whether the new optimizations are negatively affecting your application by reverting to the behavior of earlier versions.
- If performance is affected as soon as you start using this release, use the following command-line option to revert to the old behavior.
-Xthr:secondarySpinForObjectMonitorsUse the following command-line option to reestablish the new behavior.-Xthr:noSecondarySpinForObjectMonitors- If performance is affected after the application has run for some time, or after a period of heavy load, use the following command-line option to revert to the old behavior.
-Xthr:noAdaptSpinUse the following command-line option to reestablish the new behavior.-Xthr:AdaptSpin
Lock optimizations
This release introduces new locking optimizations that are expected to reduce memory usage and improve performance. However, there might be some situations where a smaller heap size is achieved for an application, but overall application performance decreases.
For example, if your application synchronizes on objects that are not typically synchronized on, such as Java.lang.String, run the following test:
- Use the following command-line option to revert to behavior that is closer to earlier versions and monitor application performance:
-Xlockword:mode=all- If performance does not improve, remove the previous command-line options or use the following command-line option to reestablish the new behavior:
-Xlockword:mode=default
Parent: Debugging performance problems
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