G1: higher perm gen footprint or a possible perm gen leak?

[Srinivas Ramakrishna]

I haven't narrowed it down sufficiently yet, but has anyone noticed if G1
causes a higher perm gen footprint or, worse, a perm gen leak perhaps?
I do realize that G1 does not today (as of 7u40 at least) collect the perm
gen concurrently, rather deferring its collection to a stop-world full
gc. However, it has just come to my attention that despite full stop-world
gc's (on account of the perm gen getting full), G1 still uses more perm gen
space (in some instacnes substantially more) than ParallelOldGC even after
the full stop-world gc's, in some of our experiments. (PS: Also noticed
that the default gc logging for G1 does not print the perm gen usage at
full gc, unlike other collectors; looks like an oversight in logging
perhaps one
that has been fixed recently; i was on 7u40 i think.)

While I need to collect more data using non-ParallelOld, non-G1 collectors
(escpeially CMS) to see how things look and to get closer to the root
cause, I wondered if anyone else had come across a similar issue and to
check if this is a known issue.

I'll post more details after gathering more data, but in case anyone has
experienced this, please do share.

thank you in advance, and Happy New Year!
-- ramki
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mail.openjdk.java.net/pipermail/hotspot-gc-use/attachments/20140103/cffda9b9/attachment.html