> > As I understand it, it would actually not work because > instances that > > peak at 512M but then go back down to, say, 128M, would still never > > return the unused memory to the OS so it can be used by > other instances. > > Not true - that's the whole point of the -Xms setting. If GC > can squeeze the heap down, it will do so and avoid > allocations in the now unused virtual space. There are some > heuristics in place within GC to avoid bouncing up and down, > so heap usage has to stay low for a while before you'll see a > lower upper limit and a corresponding reduction in the real > memory usage. (Note that the unused virtual space may not be > returned to the OS, but the real space behind it won't be > referenced so the pages will age out - but only if the OS > needs the space for some other process.) > > - Chuck > >
This is great feedback, Chuck. Right now we have 200+ instances running on the same server, most of which are set to 64MB min and max heap. Like I daid, we do not see OOM messages or paging, and top shows about 27GB of 32GB in use. Based on your comments, I would expect that changing the instances to 32M min and 512M max would not cause a negative impact. I will give this a try and report the effect. --Eric Disclaimer - February 8, 2011 This email and any files transmitted with it are confidential and intended solely for Tomcat Users List. If you are not the named addressee you should not disseminate, distribute, copy or alter this email. Any views or opinions presented in this email are solely those of the author and might not represent those of Physicians' Managed Care or Physician Select Management. Warning: Although Physicians' Managed Care or Physician Select Management has taken reasonable precautions to ensure no viruses are present in this email, the company cannot accept responsibility for any loss or damage arising from the use of this email or attachments. This disclaimer was added by Policy Patrol: http://www.policypatrol.com/ --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
