Some of the observations during the GC call monitoring / heap dump from JMAP:
Tomcat Version Stages Java Heap Usage Java Heap Capacity Virtual memory (by top) Resident Memory (by top) Tomcat 6 After tomcat startup 17.18 MB 367.8 MB 6712 MB 175 MB After functional operation 18.77 MB 367.8 MB 6745 MB 207 MB After Operation 45.51 MB 331.0 MB 6745 MB 235 MB Tomcat 7 After tomcat startup 57.90 MB 655.8 MB 6795 MB 423 MB After functional operation 97.64 MB 655.8 MB 6828 MB 558 MB After Operation 142.58 MB 1864.0 MB 6828 MB 1000 MB Observation: • Top’s reported virtual memory is approximately same. • Resident memory correlates with Java heap capacity. Refer to next slide for details. -----Original Message----- From: André Warnier [mailto:a...@ice-sa.com] Sent: Tuesday, March 24, 2015 9:00 PM To: Tomcat Users List Subject: Re: Tomcat 7 (7.0.54) memory consuption is very high(3 times) than Tomcat 6 (6.0.28) Johan Compagner wrote: >> >> I understand all that. But the basic view, from a sysadmin's point >> of view is this : >> >> Tomcat 6(6.0.28) >> Virtual Memory: 6772 MB >> Resident Memory: 81 MB >> >> Tomcat 7(7.0.54) >> Virtual Memory: 6778 MB >> Resident Memory: 148 MB >> >> > what does that Resident exactly mean here? > i guess the total heap the java vm has taken after startup? > > Because that could be quite logical, maybe tomcat 7 needs a lot more > data because of that annotation scanning Doesn't it load in way more > classes? > All that processing and then also maybe loading in up front way more > classes then before will mean that the heap (and none heap in this > scenario) is already way more loaded. > That's the kind of thing that I mean. The OP is asking : assuming the same host, the same JVM, the same startup parameters, the same default ROOT application, why does Tomcat 7 seem to be using 70 MB more RAM at startup than Tomcat 6 ? The answer can be : - it doesn't matter. The numbers shown are wrong, and if you run 10 instances of Tomcat 7 at the same time, you will see that they are not really using 700 MB more than before. or - it is normal and expected. Tomcat 7 - because of the new Servlet Spec - needs to borogrove the watchamecalits, and this is using 70 MB more heap than before. In return, you get a 25% performance improvement later.. or - we have no clue. It does not happen on other machines, so there must be something special on your machine, and to find out what we need heap dumps. or ??? The OP just wants to know which, but instead we are just telling him that he should take heap dumps or examine cryptic memory allocation displays etc.. He may not be adverse to that in the end, but some basic preliminary guidance may be helpful. --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org<mailto:users-unsubscr...@tomcat.apache.org> For additional commands, e-mail: users-h...@tomcat.apache.org<mailto:users-h...@tomcat.apache.org> DISCLAIMER: ----------------------------------------------------------------------------------------------------------------------- The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only. It shall not attach any liability on the originator or NEC or its affiliates. Any views or opinions presented in this email are solely those of the author and may not necessarily reflect the opinions of NEC or its affiliates. Any form of reproduction, dissemination, copying, disclosure, modification, distribution and / or publication of this message without the prior written consent of the author of this e-mail is strictly prohibited. If you have received this email in error please delete it and notify the sender immediately. . -----------------------------------------------------------------------------------------------------------------------
