4 Replies Latest reply on Jan 25, 2007 3:55 PM by 843829

    calling java program from makefile with Xmx2G argument

    843829
    843829 Jan 17, 2007 12:30 AM
      Hello,

      a have makefile with one target, which runs java program. 
      all:
        java -Xmx2G -cp ./numerika_java/classes/ numeric.fem.vector.ElementVe
ctorStatic
      When I run the program with -Xmx2G 'manually' from command line 
      java -Xmx2G -cp ./numerika_java/classes/ numeric.fem.scalar.ElementScalarStatic
      everything works fine.

      When I call the make target by make all, I recieved error 
      Error occurred during initialization of VM
Could not reserve enough space for object heap
Could not create the Java virtual machine.
make: *** [all] Error 1
      I have to go down with Xmx memory to approx 1500M, then it runs from make with no error too.

      I use linux with standard make.

      I'll be thankfull for any suggestions.

      Miro
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        • 1. Re: calling java program from makefile with Xmx2G argument
          843829
          843829 Jan 19, 2007 5:18 AM (in response to 843829)
          When make is running there isn't enough swap space to let us reserve 2GB for the Java object heap. We try to mmap the space and fail, so we print that error message. When make isn't running we are able to mmap the 2GB and we are happy. I'm sort of guessing here, based on a lot of experience. You could use something like vmstat to watch your available swap space.

          If you are running that close to the edge of running out of swap space (well, 500MB isn't that close to the edge) you will have to be careful what else you run even if you are able to get your Java application started. You don't say how much physical memory (and swap space) you have, but if you don't have enough physical memory to run your Java application you won't like the performance you get (paging for each reference to the heap is painful).
          • 2. Re: calling java program from makefile with Xmx2G argument
            843829
            843829 Jan 20, 2007 3:14 PM (in response to 843829)
            Thank you for input.

            I have 2.5GB of RAM + another 768MB of swap space.
            Right now, when trying to run the make command, system has 2.1GB of RAM free and 740MB of swap free.
            vmstat gives following output: 
            procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 0  0  25188 2225148   4924  81980    0    1    27    53 1160  807 12  2 85  1  0
            I made another experiments. With make, I can run program with Xmx1840M (Xmx1850 fails), without make, I can run program with Xmx2620M.
            Difference seams to be the whole swap space... I tried the experiment without mounted swap and results are same.

            Message was edited by:
            miroslav_simko

            added results when not mounted swap
            • 3. Re: calling java program from makefile with Xmx2G argument
              843829
              843829 Jan 25, 2007 1:02 PM (in response to 843829)
              Hi,
              I have the same problem too.
              I'm using Linux fedora with jdk1.5.0_09
              and a Dell with two
              Intel(R) Xeon(R) CPU
              5130 @ 2.00GHz

              and 4151240 kB of ram

              well the java -Xmx gets up to 2630m
              thus preventing me to use more than this.
              Any suggestions to break the wall?
              • 4. Re: calling java program from makefile with Xmx2G argument
                843829
                843829 Jan 25, 2007 3:55 PM (in response to 843829)
                Basic solution is to move to 64-bit system.

                While you may try to fight for hundred MB here and there, general problem is that under linux (and most other 32-bit operating systems) there is a limit to maximum memory one process can allocate. I think (but I'm not an expert here) that for linux you will get 3GB for everything (code, libraries, heap, stack etc) and there are some limits how you can split memory between these parts.

                I recall seeing some kernel patch which allowed to push this limit a bit - but generally, if you are so close to the border it is time to think about either changnig the approach (more jvms, cluster, etc) or moving to big heaps (64-bit systems or Azul applicance).