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Performance-Tips.txt
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Performance-Tips.txt
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- Don't believe all of the so called "performance-tips" on the net. If you
think you have found an optimization try it out in the real implementation
and not in a simulation. Let the implementation run at minimum 10 times, calculate
the average time, do the same with the not optimized implementation and compare.
- Keep in mind that there are different VM vendors and that they can behave differently.
- The java runtime optimizer seems to do an excellent job. So coding style is more important than
micro-level optimizations.
- Prevent as far as possible to create an iterator to iterate over an ArrayList.
- Prevent unnecessary instantiation of List's, Map's and such. Collections.emptyList() should be used
when we now beforehand that the List will be empty.
- switch instead of if..else
(e.g.
switch(XMLEvent.getEventType())
{
case XMLStreamConstants.START_ELEMENT:
//do something with the start element
break;
case XMLStreamConstants.END_ELEMENT:
//do something with the end element
break;
}
- Dynamic CPU frequency-scaling (ondemand) has a big impact (it doubles the processing time in the worst case)
to the streaming wss performance. An exact explanation for this is outstanding. I guess it has something to-do
with the pipe in the decryptionProcessor and its decryptionThread.
- Newer Intel-CPU's (Core i) are going to overclock itself (turbo mode) when just one core is in use. This is an advantage for
WSS4J-DOM but swssf can't take profit of it since we have two threads for decryption.