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Performance and scalability: Tomcat 6 increase heap beyond 1024 M

  1. Tomcat 6 increase heap beyond 1024 M (7 messages)

    We're trying to increase the memory through service.bat to 2048. We install the service fine, but when we start tomcat, we can an error message saying it was unable to start. When we change the memory heap max back to 1024, it works. Anyone know why this is and how we can up the heap? We have an 8GB RAM server and would like to use atleast 4GB for tomcat. I've read there's a 2GB limit (is this still true with jre 1.6?), but we're trying to get as much as we can out of tomcat.

    Threaded Messages (7)

  2. Use 64 bit OS[ Go to top ]

    If your OS is 32 bit, you can have only 2 GB limit. If you would like to use your 8 GB or 4 GB for JVM, you would need to move to 64 bit OS. :) ~Rajesh.B
  3. Re: Use 64 bit OS[ Go to top ]

    Well then, how can we utilize the 2 GB limit, as I stated in my previous post, tomcat won't let us use anything over 1 GB as it crashes when we try to start the server with anything more.
  4. Re: Use 64 bit OS[ Go to top ]

    You may need to check if you have enough memory left out. Are you trying to set -Xms and -Xmx to the same value and more than 1024?. Are you sure you dont have any other process which is memory intensive running in that system?. What is the error message you see in the console? ~Rajesh.B
  5. Re: Use 64 bit OS[ Go to top ]

    It does not matter if system has any other process running on it and this virtual is not mapped to the physical memory , please understand that. What might be the proobelm is that even though Windows assuming its windows allows 2GB per process and so it allows 2GB for the JVM but the whole two GB cant be used by the JVM so it has other system specific overheads that need to be taken care of by the OS and thus th emax that could be allotted using the Xmx optiobn is somewhere aroubnd 1.4 to 1.5 GB
  6. Memory fragmentation[ Go to top ]

    There is an issue with memory fragmentation in the OS that prevents the JVM from going above =< 1500mb At least on windows.
  7. http://www.ittvis.com/services/techtip.asp?ttid=3346
  8. http://www.theserverside.com/tt/articles/article.tss?l=ScalingYourJavaEEApplications