IBM User Guide for Java V7 on Windows > Troubleshooting and support > Using diagnostic tools > Tracing Java applications and the JVM > Where does the data go?

Writing trace data to a file

You can write trace data to a file continuously as an extension to the in-storage trace, but, instead of one buffer per thread, at least two buffers per thread are allocated, and the data is written to the file before wrapping can occur.

This allocation allows the thread to continue to run while a full trace buffer is written to disk. Depending on trace volume, buffer size, and the bandwidth of the output device, multiple buffers might be allocated to a given thread to keep pace with trace data that is being generated.

A thread is never stopped to allow trace buffers to be written. If the rate of trace data generation greatly exceeds the speed of the output device, excessive memory usage might occur and cause out-of-memory conditions. To prevent this, use the nodynamic option of the buffers trace option. For long-running trace runs, a wrap option is available to limit the file to a given size. It is also possible to create a sequence of files when the trace output will move back to the first file once the sequence of files are full. See the output option for details. You must use the trace formatter to format trace data from the file.

Because trace data is buffered, if the JVM does not exit normally, residual trace buffers might not be flushed to the file. If the JVM encounters a fatal error, the buffers can be extracted from a system dump if that is available. When a snap file is created, all available buffers are always written to it.

Parent: Where does the data go?

Error 404 - Not Found

The document you are looking for may have been removed or re-named. Please contact the web site owner for further assistance.