IBM User Guide for Java V7 on Windows > Troubleshooting and support > Using diagnostic tools > Shared classes diagnostic data > Understanding shared classes diagnostics output

VerboseIO output

The verboseIO output is far more detailed, and is used at run time to show classes being stored and found in the cache.

VerboseIO output provides information about the I/O activity occurring with the cache, with basic information about find and store calls. You enable verboseIO output by using the verboseIO suboption of -Xshareclasses. With a cold cache, you see trace like this example

Finding class org/eclipse/ui/internal/UIWorkspaceLock in shared cache for cldr id 0... Failed.
Finding class org/eclipse/ui/internal/UIWorkspaceLock in shared cache for cldr id 3... Failed.
Finding class org/eclipse/ui/internal/UIWorkspaceLock in shared cache for cldr id 17... Failed.
Storing class org/eclipse/ui/internal/UIWorkspaceLock in shared cache for cldr id 17... Succeeded.

Each class loader is given a unique ID. The bootstrap loader has an ID of 0. In the example trace, class loader 17 follows the class loader hierarchy by asking its parents for the class. Each parent asks the shared cache for the class. Because the class does not exist in the cache, all the find calls fail, so the class is stored by class loader 17.

After the class is stored, you see the following output for subsequent calls:

Finding class org/eclipse/ui/internal/UIWorkspaceLock in shared cache for cldr id 0... Failed.
Finding class org/eclipse/ui/internal/UIWorkspaceLock in shared cache for cldr id 3... Failed.
Finding class org/eclipse/ui/internal/UIWorkspaceLock in shared cache for cldr id 17... Succeeded.

Again, the class loader obeys the hierarchy, because parents ask the cache for the class first. This time, the find call succeeds. With other class loading frameworks, such as OSGi, the parent delegation rules are different. In such cases, the output might be different.

Parent: Understanding shared classes diagnostics output

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