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 12:43:16 PDT 2008


Sorry, corrected the runtime list address below. Apologies for the resulting clutter.

-- ramki

----- Original Message -----
From: Y Srinivas Ramakrishna <Y.S.Ramakrishna at Sun.COM>
Date: Friday, April 4, 2008 12:40 pm
Subject: Reporting large Java heap allocations (was Re: RMI Activity Threads Lock GC o/p)
To: Michael Finocchiaro <michael.finocchiaro at gmail.com>
Cc: Keith Holdaway <Keith.Holdaway at sas.com>, "hotspot-gc-use at openjdk.java.net" <hotspot-gc-use at openjdk.java.net>, hotspot-runtime-dev at openjdk.java.net


> 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-runtime-dev at o.j.n might be able to help, so i have cross-posted
> to that list.
> 
> -- ramki
> 
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