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We have a PHP webapp that calls a Java binary to produce a PDF report (with JasperReports). The Java binary outputs the PDF to standard output and exits; the PHP then sends the PDF to browser. This Java command lasts about 3 to 6 seconds, and I think when it lasts 6 second it's because the GC kicks in. I would like to disable the GC because anyway when the command exits all memory is returned.
I would like to know how to disable it for Java 1.4.2 and for Java 1.6.0 because we are currently testing both JVM to see which performs faster..
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The best approach to tuning Java garbage collection is setting flags on the JVM. Flags can adjust the garbage collector to be used (e.g. Serial, G1, etc.), the initial and maximum size of the heap, the size of the heap sections (e.g. Young Generation, Old Generation), and more.
The advantages of Garbage Collection in Java are: It makes java memory-efficient because the garbage collector removes the unreferenced objects from heap memory. It is automatically done by the garbage collector(a part of JVM), so we don't need extra effort.
Under the Additional Properties section, click Java Virtual Machine. Uncheck the Verbose garbage collection check box. In the Generic JVM Arguments field, enter the non-standard JVM command-line options that enable the desired Garbage Collector data logging behavior.
G1 Garbage Collector is the default garbage collection of Java 9. G1 collector replaced the CMS collector since it's more performance efficient.
It sounds like you are trying to save time, but going about it the wrong way. The time saved in disabling garbage collection would be trivial (for a single task) compared to the time taken to launch and shutdown the java process. You might want to consider having a java process launch that you can ask multiple times to do the work you require if run-time performance is your goal.
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There is no way to disable garbage collection entirely. Garbage collection is only run when the JVM runs out of space, so you could give the program more memory. Add these command line options to the Java command
-Xmx256M -Xms256M This gives the program 256Mb of ram (the default is 64Mb). Garbage collection will not take 3 seconds for a default size JVM though, so you might want to investigate more closely what the program is doing. Yourkit profiler is very useful for figuring out what is taking a long time.
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