My Empty infinity loop
public static void main(String[] args) {
while (true) {}
}
And profiling in Java VisualVM (picture)
As you can see, I do not create objects. Why change a heap?
Please explain the effect. Why?
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couatl
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Nice pictures! But sorry, I didn't get your question. – Stephan Dec 13 '12 at 21:24
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See also: http://stackoverflow.com/questions/12711106/simple-java-program-increasingly-consuming-memory – assylias Dec 13 '12 at 21:35
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@assylias in your link create new object, and Swing. In my example Empty loop. – couatl Dec 13 '12 at 21:39
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@couatl Absolutely - I only mentioned it because it is related and some of the comments there do apply but your question is different. – assylias Dec 13 '12 at 21:41
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Basically any Java application is multithreaded, the fact that your main thread does not allocate memory does not mean that the others do not allocate either. In fact it is very likely that by attaching via VisualVM and showing the GC tab you have spawned some threads in the VM to monitor GC resources and feed VisualVM the metrics that become those shiny charts. And that monitoring will likely allocate some resources of its own to do its job.
gpeche
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I do not think you can. The most you can do is use some OS level tools (vmstat, top, etc). And anyway even if you do not monitor the application with VisualVM, there is JMX, the finalizer thread, the AWT thread etc etc etc. Assume that your application *will have* some thread allocating some resources in the background – gpeche Dec 13 '12 at 21:46