Increase heap size in Java to prevent java.lang.OutOfMemoryError

Java programs executes in JVM uses Heap of memory to manage the data. If your Java program requires a large amount of memory, it is possible that the virtual machine will begin to throw OutOfMemoryError instances when attempting to instantiate an object. The default heap size if 1 MB and can increase as much as 16 MB.

Setting/Increase JVM heap size

It is possible to increase heap size allocated by the Java Virtual Machine (JVM) by using command line options.
Following are few options available to change Heap Size.

1 2 3

-Xms<size>        set initial Java heap size -Xmx<size>        set maximum Java heap size -Xss<size>        set java thread stack size

JVM crash on a Red Hat machine ( Java 1.4.2 applicationwith ) with a SIGSEGV error. -Xms is 64M and -Xmx is 128M

I'm running a Java 1.4.2 application on a Red Hat machine that causes the JVM to crash with a SIGSEGV error. -Xms is 64M and -Xmx is 128M. I first thought that the perm gen size was too low since it always has a high percentage (98/99%) when the JVM crashes. After reading more about the perm gen, though, I'm not so sure. Am I looking down the right path by thinking it may be the perm gen size being too low or is the percentage so high just because the JVM will resize it dynamically? When it crashes the perm gen's total size is around 10/11 MB and its usually 99% full.

#
# An unexpected error has been detected by HotSpot Virtual Machine:
#
#  SIGSEGV (0xb) at pc=0xb7c70b4c, pid=5342, tid=2810452880
#
# Java VM: Java HotSpot(TM) Client VM (1.4.2_16-b05 mixed mode)
# Problematic frame:
# V  [libjvm.so+0x196b4c]
#


Heap
 def new generation   total 4608K, used 3372K [0xa7900000, 0xa7e00000, 0xa82d0000)
  eden space 4096K,  78% used [0xa7900000, 0xa7c27780, 0xa7d00000)
  from space 512K,  27% used [0xa7d80000, 0xa7da3ad8, 0xa7e00000)
  to   space 512K,   0% used [0xa7d00000, 0xa7d00000, 0xa7d80000)
 tenured generation   total 60544K, used 21376K [0xa82d0000, 0xabdf0000, 0xaf900000)
   the space 60544K,  35% used [0xa82d0000, 0xa97b0210, 0xa97b0400, 0xabdf0000)
 compacting perm gen  total 11264K, used 11159K [0xaf900000, 0xb0400000, 0xb3900000)
   the space 11264K,  99% used [0xaf900000, 0xb03e5c30, 0xb03e5e00, 0xb0400000)
  
  
   ---------------  S Y S T E M  ---------------

OS:Red Hat Enterprise Linux Client release 5 (Tikanga)

uname:Linux 2.6.18-8.1.8.el5 #1 SMP Mon Jun 25 17:06:19 EDT 2007 i686
libc:glibc 2.5 NPTL 2.5
rlimit: STACK 10240k, CORE 0k, NPROC 16370, NOFILE 1024, AS infinity
load average:0.00 503...

CPU:total 2 family 15, cmov, cx8, fxsr, mmx, sse, sse2

Memory: 4k page, physical 1034572k(314260k free), swap 2096472k(2096472k free)

vm_info: Java HotSpot(TM) Client VM (1.4.2_16-b05) for linux-x86, built on Sep 17 2007 00:34:43 by unknown with unknown compiler