Java Refuses to Start - Could not reserve enough space for object heap

Question

Background  We have a pool of aproximately 20 linux blades   Some are running Suse  some are running Redhat   ALL share NAS space which contains the following 3 folders     NAS app java - a symlink that points to an installation of a Java JDK   Currently version 1 5 0 10  NAS app lib - a symlink that points to a version of our application   NAS data - directory where our output is written   All our machines have 2 processors  hyperthreaded  with 4gb of physical memory and 4gb of swap space   We limit the number of  jobs  each machine can process at a given time to 6  this number likely needs to change  but that does not enter into the current problem so please ignore it for the time being    Some of our jobs set a Max Heap size of 512mb  some others reserve a Max Heap size of 2048mb   Again  we realize we could go over our available memory if 6 jobs started on the same machine with the heap size set to 2048  but to our knowledge this has not yet occurred   The Problem  Once and a while a Job will fail immediately with the following message   Error occurred during initialization of VM Could not reserve enough space for object heap Could not create the Java virtual machine    We used to chalk this up to too many jobs running at the same time on the same machine   The problem happened infrequently enough  MAYBE once a month  that we d just restart it and everything would be fine   The problem has recently gotten much worse   All of our jobs which request a max heap size of 2048m fail immediately almost every time and need to get restarted several times before completing   We ve gone out to individual machines and tried executing them manually with the same result   Debugging  It turns out that the problem only exists for our SuSE boxes   The reason it has been happening more frequently is becuase we ve been adding more machines  and the new ones are SuSE      cat  proc version  on the SuSE boxes give us   Linux version 2 6 5-7 244-bigsmp  geeko buildhost   gcc version 3 3 3  SuSE Linux    1 SMP Mon Dec 12 18 32 25 UTC 2005    cat  proc version  on the RedHat boxes give us   Linux version 2 4 21-32 0 1 ELsmp  bhcompile bugs build redhat com   gcc version 3 2 3 20030502  Red Hat Linux 3 2 3-52    1 SMP Tue May 17 17 52 23 EDT 2005    uname -a  gives us the following on BOTH types of machines   UTC 2005 i686 i686 i386 GNU Linux   No jobs are running on the machine  and no other processes are utilizing much memory   All of the processes currently running might be using 100mb total    top  currently shows the following   Mem    4146528k total   3536360k used    610168k free    132136k buffers Swap   4194288k total         0k used   4194288k free   3283908k cached    vmstat  currently shows the following   procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy id wa 0  0      0 610292 132136 3283908    0    0     0     2   26    15  0  0 100  0   If we kick off a job with the following command line  Max Heap of 1850mb  it starts fine   java bin java -Xmx1850M -cp helloworld jar HelloWorld Hello World   If we bump up the max heap size to 1875mb it fails   java bin java -Xmx1875M -cp helloworld jar HelloWorld Error occurred during initialization of VM Could not reserve enough space for object heap Could not create the Java virtual machine    It s quite clear that the memory currently being used is for Buffering Caching and that s why so little is being displayed as  free   What isn t clear is why there is a magical 1850mb line where anything higher means Java can t start   Any explanations would be greatly appreciated

User · Answer

I am using SOA env  Decreased Xmx from 1024 to 768 in setSOADomainENV cmd resolved the issue   REM set DEFAULT MEM ARGS -Xms512m -Xmx1024m set DEFAULT MEM ARGS -Xms512m -Xmx768m

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Given that none of the other suggestions have worked  including many things I d have suggested myself   to help troubleshoot further  could you try running   sysctl -a   On both the SuSE and RedHat machines to see if there are any differences  I m guessing the default configurations are different between these two distributions that s causing this

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I recently faced this issue   I have 3 java applications that start with 1024m or 1280m heap size  Java is looking at the available space in swap  and if there is not enough memory available  the jvm exits   To resolve the issue  I had to end several programs that had a large amount of virtual memory allocated   I was running on x86-64 linux with a 64-bit jvm

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What is the JVM used   I know that BEA JRockit does not exceed 1850mB for max heap size  It does not fail but warns the user that it will not use more than 1850mB   I don t know why there is such a limit but I know it exists for BEA JRockit   Best regards

User · Answer

ulimit max memory size and virtual memory set to unlimited

User · Answer

This maybe way off the track  but there are two things that spring to mind  Both of the following assume that you are running a 32bit version of Linux   There is a process size limit on linux  seem to remember on CentOS was around 2 5gb and is configured in the kernel  i e  a recomple to change   Your process might be hitting that once you add up all the JVM code   Permgen space and all the rest of the JVM libraries   The second thing is something I ve come across that you may be running out of address space  sounds wierd I know  Had a problem running Glassfish with a 1 5Gb heap  when it tried to complie a JSP my forking javac it would fail because the OS couldn t allocate enough address space for the newly created process even though there was 12gb of memory in the box  There may be something similar going on here   I m afraid the only solutions to the above two where to upgrade to a 64bit kernel   Hope this is of some use

User · Answer

You re using a 32-bit OS  so you re going to be seeing limits on the total size due to that   Other answers have covered this in more detail  so I ll avoid repeating their information   A behaviour that I noticed with our servers recently is that specifying a maximum heap size with -Xmx while not specifying a minimum heap size with -Xms would lead to Java s server VM immediately attempting to allocate all of the memory needed for the maximum heap size   And sure  if the app gets up to that heap size  that s the amount of memory that you ll need   But the chances are  your apps will be starting out with comparitively small heaps and may require the larger heap at some later point   Additionally specifying the minimum heap size will let you start your app start with a smaller heap and gradually grow that heap   All of this isn t going to help you increase your maximum heap size  but I figured it might help  so

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I upgraded the memory of a machine from 2GB to 4GB  and started to get the error straight away     java -version Error occurred during initialization of VM Could not reserve enough space for object heap Could not create the Java virtual machine    The problem was the ulimit  which I had set at 1GB for the addressable space  Increasing it to 2GB solved the issue   -Xms and -Xmx had no effect   Looks like java tries to get memory in proportion to the available memory  and fails if it can t

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I wrote two applications  one medium sized  and the other  fairly small  I d fire up the medium sized one  on linux  centos   without any args   java server   and it would run just fine  But when I then fired up the smaller app with  java client   it would tell me it couldn t reserve enough space  and wouldn t run  I experimented  and used the -Xms and -Xmx both with 10m  and they would both run without complaint    Go figure

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It seems that for 32-bit servers there is a JVM limitation that cannot be overcome  unless you find a special 32-bit JVM that does not impose a 2GB limit or less    This thread on The Server Side has more details including several people who tested out various JVMs on 32-bit architectures   IBM s JVM seems to allow 100 more MB but that s not really going to get you what you want   http   www theserverside com discussions thread tss thread id 26347  The  real  solution is to use a 64-bit server with a 64-bit JVM to get heaps larger than 2GB per process   However  it s important to also consider the impact of increasing your address size  not just the addressable space  by using a 64-bit JVM   There will likely be performance and memory impacts for processing using less than 4GB of memory   Food for thought  do each of these jobs really require 2GB of memory  Is there any way for the jobs to be modified to run within 1 8GB so this limit is not a problem

User · Answer

You need to look at upgrading your OS and Java   Java 5 0 is EOL but if you cannot update to Java 6  you could use the latest patch level 22   32-bit Windows is limited to   1 3 GB so you are doing well to se the maximum to 1 8   Note  this is a problem with continous memory  and as your system runs its memory space can get fragmented so it does not suprise me you have this problem   A 64-bit OS  doesn t have this problem as it has much more virtual space  you don t even have to upgrade to a 64-bit version of java to take advantage of this   BTW  in my experience  32-bit Java 5 0 can be faster than 64-bit Java 5 0   It wasn t until many years later that Java 6 update 10 was faster for 64-bit

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Running a 32-bit OS is a mistake  you should definitely upgrade at the earliest convenience   I don t know whether Java requires its heap to be in a single contiguous chunk  but if it does  asking for 1 8G of heap on a 32-bit box sounds like a tall order  You re assuming that there is a chunk of address space  almost half of it  free at JVM startup time   Depending on what other libraries are loaded at the time  there may not be  Libraries can allocate memory anywhere they like  so it could fragment your address space sufficiently that 1 8G is not available in one chunk   There is only about 3G address space max available on Linux 32-bit anyway  Libraries and the JVM itself uses some to start with

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In Windows  I solved this problem editing directly the file  bin cassandra bat  changing the value of the  Xms  and  Xmx  JVM OPTS parameters  You can try to edit the  bin cassandra file  In this file I see an commented variable JVM OPTS  try to uncomment and edit it

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Steps to be execute      to resolve the  Error occurred during initialization of VM Could not reserve enough space for object heap Could not create the Java virtual machine   Step 1  Reduce the memory what earlier you used   java  -Xms128m -Xmx512m -cp simple jar   step 2  Remove the RAM some time from the mother board and plug it and restart    may it will release the blocking heap area memory   java  -Xms512m -Xmx1024m -cp simple jar   Hope it will work well now     -

User · Answer

As suggested in other responses the problem is causes by exhaustion of virtual address space  A 32bit linux userspace program is usually limited to 3GB of AS  the remaining 1GB is used by the kernel  rationale  since the top 1GB is kernel fixed mapping it s not necessary to touch the page table when serving syscalls    RHEL kernels  however  implement the so called 4GB 4GB split where the full 4GB AS is available to userspace processes at cost of a slight runtime overhead  the kernel lives in a separate 4GB virtual AS

[java] Java Refuses to Start - Could not reserve enough space for object heap

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