How to reset loaded classes fast in java?

Question

I'm using a custom classloader to load some java classes. I need to execute some methods from these loaded classes in a loop. For each loop iteration I need a fresh initialization of all the classes (all static fields). I have measured that the execution time is three times slower if I use a new classloader for each iteration than the execution time when not using a fresh classloader in each iteration.

Can I reset the loaded classes to their initial state without loading them with a new classloader?

Or is there a way to speed up recurring loading of the same classes in different classloaders?

score 2 · Answer 1 · answered Apr 21 '12 at 21:05

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When you load the class with a new classloader, the JMV will almost certainly have to re-jit the byte code. Until it does, the first uses of the newly loaded classes will be slower.

I assume these classes are library code which you cannot modify? Because the fact that you're having to use the classes in this way suggests flawed design to me.

answered Apr 21 '12 at 21:05

ulmangt

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It's a security feature. The classes are uploaded by the user and executed inside the server system. – tangens Apr 22 '12 at 06:12

score 0 · Answer 2 · answered Apr 23 '12 at 15:05

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Just from the top of my head: can you take a snapshot of the initial state of the class using reflection and then restoring it?

answered Apr 23 '12 at 15:05

slvr

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What if the fields are final? – Martin Tuskevicius Apr 23 '12 at 15:11
See this http://stackoverflow.com/questions/3301635/change-private-static-final-field-using-java-reflection – slvr Apr 24 '12 at 05:51

How to reset loaded classes fast in java?

2 Answers2