why perm generation is continuously increasing?
fancyerii at gmail.com
Thu Feb 16 22:52:13 PST 2012
I want to use btrace to locate which function call String.intern()
it seems it's not feasible
any other methods?
I tried trace method call of String, constructor method and trim method is
ok. but native method like intern is not.
On Fri, Feb 17, 2012 at 2:00 PM, Alexey Ragozin <alexey.ragozin at gmail.com>wrote:
> Normally permanent generation is collect only during Full GC.
> -XX:+CMSClassUnloadingEnabled will enable permanent space collection as a
> part of concurrent old space collection.
> Date: Thu, 16 Feb 2012 20:53:59 +0800
>> From: Li Li <fancyerii at gmail.com>
>> Subject: Re: why perm generation is continuously increasing?
>> To: hotspot-gc-use <hotspot-gc-use at openjdk.java.net>
>> 0cTCpCB74wD03VgYe_GhgPj78mcU_pk3syaQ at mail.gmail.com>
>> Content-Type: text/plain; charset="iso-8859-1"
>> I got it. we use String.intern for temporary variables.
>> I used jmap -permstat and found that.
>> btw jmap -permstat will cause jvm hang and should be carefully used.
>> it hangs for a few minutes!
>> On Thu, Feb 16, 2012 at 6:55 PM, Li Li <fancyerii at gmail.com> wrote:
>> > hi all,
>> > I found our application's perm generation size is continuously
>> > increasing and will reach 100%(we limit maxPermSize to 256MB) and
>> perform a
>> > full gc(which will pause for 10s).after gc, perm size usage falls to
>> > 50% and again increasing. what kind of objects will be allocated to perm
>> > generation? we don't use reflection in our application.
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