very slow perm gen verification

Y. Srinivas Ramakrishna y.s.ramakrishna at oracle.com
Thu May 12 12:23:35 PDT 2011


John, Here you go:-

http://hg.openjdk.java.net/jdk7/hotspot-gc/hotspot/rev/5134fa1cfe63

More historical data (of how the problem first surfaced of a
day-one badness) can be found in the CR.

Don't know though if this is related to what you are seeing, especially
if you're only seeing this with the perm gen.

- ramki

On 5/12/2011 11:49 AM, Y. Srinivas Ramakrishna wrote:
> With the framework collectors there was a badness that
> would cause O(n^2) in the size of the perm gen in the phase
> that checks that clean cards do not have cross-generational
> pointers. I fixed it a few weeks ago so it is now O(n) -- i can dig up the
> CR if you can't find it. Are you seeing this with a specific
> collector or all?
>
> -- ramki
>
> On 5/12/2011 10:33 AM, John Coomes wrote:
>> John Coomes (John.Coomes at oracle.com) wrote:
>>> When running some nsk tests, I saw several timeouts which appear to be
>>> due to very slow verification of the perm gen (i.e., 10+ minutes to
>>> verify a 64MB perm gen (par scavenge)), which is done as the jvm is
>>> exiting. Happens frequently, but not every time; and w/my changes as
>>> well as w/jdk7-b141.
>>>
>>> I vaguely recall some discussion of this a few months ago, but can't
>>> find any record of it :-(. Sound familiar to anyone?
>>
>> In case it's not obvious to some, the verification is done only in
>> non-product builds.
>>
>> -John
>



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