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.


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:

  1. Use the following command-line option to revert to behavior that is closer to earlier versions and monitor application performance:
    -Xlockword:mode=all
  2. 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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