Reporting large Java heap allocations (was Re: RMI Activity Threads Lock GC o/p)

Y Srinivas Ramakrishna Y.S.Ramakrishna at Sun.COM
Fri Apr 4 12:40:48 PDT 2008




Hi Fino --

> Yes, there is an environment variable on AIX called
> ALLOCATION_THRESHOLD=<size in bytes> that when set will have the JVM 
> send on
> error to stdout (or stderr not sure) when an allocation greater than <size
> in bytes> occurs. This could be useful, well at least for us, when dealing
> with code that sends back way too much data. By the heap blowing up, I 
> mean
> a sudden huge jump in memory consumption from which the heap may have 
> a real
> hard time recovering if at all. Even better would be a flag that threw 
> a
> stack trace when that allocation occurs.

...

I don't think there is a jvm (or env option) w/Hotspot that would do that
(but i may be wrong).

However, I also wonder whether (with appropriate caveats, see below, on appropriate
platforms) one might be able to elicit (an approximation to) that data (at
sufficiently large values of <size_in_bytes>) by leveraging dtrace; someone
on hotspot-gc-runtime at o.j.n might be able to help, so i have cross-posted
to that list.

-- ramki

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