This section describes the notes on using the user-extended trace based performance analysis.

• If the methods to be traced are invoked frequently, it might be difficult to identify the method that causes performance deterioration, due to the performance deterioration caused by the processing overhead of the user-extended trace based performance analysis. Therefore, in the methods to be traced, specify a method that serves as the entry to the processing that can identify the cause of deterioration.
  For example, in the case of applications with a method invocation relationship as shown in the following figure, take method 1 (trace collection point 1) that serves as an entry to processing as the target. If you specify the methods 4, 5, and 6 of the trace collection point 2, and if the processing of the user-extended trace based performance analysis for these methods takes time, the performance measurement of this application might be affected.
  

  Figure 7-16 Method invocation relationship in an application

  

• If you use the user-extended trace based performance analysis for a method invoked before the root application information is acquired, the root application information might be output with 0.
• If you increase the frequency of invoking the method to be traced and specify a property that increases the amount of trace output, the amount of PRF trace file output increases. In this case, increase the number of PRF trace files or the PRF trace file size. For details on how to change the number and size of PRF trace files, see 10.3.1 Setting up the performance tracer in the uCosminexus Application Server Management Portal Operation Guide.
  Note that the increase in the amount of PRF trace files that are output causes the following events:
  
  • Overhead occurs due to the writing to the trace files and leads to performance deterioration.
  • The number of trace files is switched due to a large amount of writing, and the J2EE server can no longer obtain the trace that could be obtained.
  For normal operations, specify the contents of the user-extended trace based performance analysis configuration file appropriately and adjust the trace collection amount.
  
• The application classes are rewritten in the user-extended trace based performance analysis. At this time, if the rewritten class size exceeds 64 KB, the rewriting fails. In this case, take actions such as dividing the class to reduce the class size.