CPU Timing

With the timing method, mBProfiler records the precise number of times each method of the executed application is invoked, and the time duration of each method execution.

The CPU timing method is recommended for use with applications that execute very briefly (within milliseconds) or have many threads serving small requests (such as servlet applications). The advantage of this method is that it is very precise. The disadvantages, however, are that it slows down considerably the tested application, and that it is not scalable and cannot be used for long time running applications. The considerable slow down can lead to distortion of the collected information. This slow down is due to the fact that this profiler runs in the tested application's threads and all method calls are slower.

Timing mode is not available for some JVMs.

Turn Timing On

To s up the timing method to be your way for collecting CPU profiling information:

1. Go to the CPU Call Tree view.
2. In the right upper corner of the view, open the pull-down menu.
3. Switch to Timing Mode.

   

or

1. Go to Window > Preferences > mBProfiler (or to Eclipse >Preferences if you are using OS X).
2. In the Preferences window, check the timing option under CPU Method.

   

   Next to the timing option, use the Filter methods less than field if needed to see only methods/stack frames whose duration is greater than certain execution time (in milliseconds).

3. Click OK.

   If you change this setting after the CPU profiling has already begun, the new setting will take effect the next time you start profiling.

Together with the timing method you can use the Use real CPU time option, available in the mBProfiler preferences and in the pull-down menu of the CPU Call Tree view. The option defines if mBProfiler will show the real time of the CPU usage, or the total execution time of the tested thread/method. For example, let's have a thread that was started at 1:30 PM and stopped at 2:30 PM. However, the thread wasn't active all the time but was active (did some work and caused CPU usage) for a total of 5 minutes. If the Use real CPU time option is not checked, mBProfiler will show a whole 1 hour of work for the tested thread. If that option is checked, however, mBProfiler will show only 5 minutes of work for the thread.

If the profiler agent does not support real CPU profiling, the mBProfiler will show an error in the CPU Call Tree view:

"Real CPU profiling is not supported for this platform"

Without the Use real CPU time option

The figure below shows the CPU tree when the timing CPU method is used, and the Use real CPU time option is not active.

• [total] 1 shows the total number of the threads. The time(ms) entry at the same row shows the total time of the CPU profiling session.
• Thread nodes show the total time under time the thread has existed on this CPU profiling session as well as its actual run time under own time in case thread profiling is started.
• Method nodes show the total execution time the method has occupied, method's own time (without children's time) and the number of invocations of the method.

With the Use real CPU time option

The figure below shows the CPU tree when the timing CPU method is chosen, and the Use real CPU time option is active.

• [total] 1 shows the total number of threads. The time entry at the same row shows the total time of the CPU profiling session. The own time (ms) entry shows the total CPU time consumed by the profiled application during the session.
• Thread nodes show the CPU time of the threads in both the time and own time columns.
• Method nodes show total CPU time the method has occupied, the method's run time (without children's time) and the number of invocations of the method.