Java virtual machine memory

Goodmorning to everyone,
i would let you know about a problem i found. i am using a jtable and i want lo load some cells from a file.Every time i load some cells i see the used memory, free memory and max memory.the max memory value is 64mb (while i have 256mb on my pc).i have to load a file of 30mb in this jtable and it fires me a "out of memory". the question i want to post is: "how can i enlarge the memory used by the virtual machine(64mb-->256mb)??", or "how can i solve this problem??".
i thank you all and i am sorry for my bad english
bye!

load a file of 30mb in this jtable and it fires me a
"out of memory". the question i want to post is: "how
can i enlarge the memory used by the virtual
machine(64mb-->256mb)??", or "how can i solve this
problem??".Wow. If you really want to do it that way, make sure you have a swap file so the total memory can accommodate all the programs you want to run.
Then specify
java -Xms64M -Xmx256M
Just beware the application is going to be dead slow once the OS starts swapping.

Similar Messages

The crash happened outside the java virtual machine in native code

Hi,
I have a biometric device with which I am given some C++ dlls. I am trying to call methods inside these using java (jna). I am loading the dll "zkemsdk.dll+" as follows:
zkemkeeper INSTANCE1 = (zkemkeeper)Native.loadLibrary("zkemsdk", zkemkeeper.class);//zkemsdk is the dll, I am loading the dll here.
Then, I am calling the function:
zkemkeeper.INSTANCE1.Z_Connect_NETEX("ip address",4370);//Z_Connect_NETEX is a function inside zkemsdk.dll
This returns me true or false based on whether am connected to the biometric device or not.Thus I am able to invoke this method without issues. But for other methods inside the dll, run time exception is thrown in console:
Can someone help me resolve this issue. ??? Following is the content of the log file generated.
# A fatal error has been detected by the Java Runtime Environment:
# EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x0351fe3b, pid=1664, tid=3832
# JRE version: 6.0_20-b02
# Java VM: Java HotSpot(TM) Client VM (16.3-b01 mixed mode, sharing windows-x86 )
# Problematic frame:
# C [zkemsdk.dll+0xfe3b]
# If you would like to submit a bug report, please visit:
# http://www.java.net/external?url=http://java.sun.com/webapps/bugreport/crash.jsp
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.
--------------- T H R E A D ---------------
Current thread (0x003a9000): JavaThread "main" [_thread_in_native, id=3832, stack(0x008c0000,0x00910000)]
siginfo: ExceptionCode=0xc0000005, reading address 0x00000106
Registers:
EAX=0x0090f7c4, EBX=0x00000001, ECX=0x00000000, EDX=0x00000001
ESP=0x0090f7b4, EBP=0x0090f848, ESI=0x00000096, EDI=0x003a9000
EIP=0x0351fe3b, EFLAGS=0x00010216
Top of Stack: (sp=0x0090f7b4)
0x0090f7b4: 00000000 0090f930 000003fc 00000103
0x0090f7c4: 0090f800 6d9532d0 373e92a0 00912ec5
0x0090f7d4: 00000401 0090f7d8 369860d1 0090f800
0x0090f7e4: 37390050 00000000 37390f90 00000000
0x0090f7f4: 0090f800 0090f930 003a9000 0090f830
0x0090f804: 10008fd8 0090f840 0090f930 00000008
0x0090f814: 0090f88c 0090fa28 0090f8f4 0090f848
0x0090f824: eb53f637 0351ffdc 00000096 00000003
Instructions: (pc=0x0351fe3b)
0x0351fe2b: 0f 53 50 8d 44 24 18 50 e8 58 7c 00 00 83 c4 0c
0x0351fe3b: 8b 4e 70 51 8b 0e 83 c3 04 53 6a 64 8d 54 24 18
Stack: [0x008c0000,0x00910000], sp=0x0090f7b4, free space=13d0090f2e8k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
C [zkemsdk.dll+0xfe3b]
C [jna5972695927945545932.tmp+0x9182]
C [jna5972695927945545932.tmp+0x2161]
C [jna5972695927945545932.tmp+0x2849]
j com.sun.jna.Function.invokeInt(I[Ljava/lang/Object;)I+0
j com.sun.jna.Function.invoke([Ljava/lang/Object;Ljava/lang/Class;)Ljava/lang/Object;+90
j com.sun.jna.Function.invoke(Ljava/lang/Class;[Ljava/lang/Object;Ljava/util/Map;)Ljava/lang/Object;+194
j com.sun.jna.Library$Handler.invoke(Ljava/lang/Object;Ljava/lang/reflect/Method;[Ljava/lang/Object;)Ljava/lang/Object;+344
j $Proxy0.Z_Beep(J)Z+19
j com.rfarrays.bhabs.fingerPrint.main([Ljava/lang/String;)V+84
v ~StubRoutines::call_stub
V [jvm.dll+0xf049c]
V [jvm.dll+0x17fcf1]
V [jvm.dll+0xf051d]
V [jvm.dll+0xf9bc5]
V [jvm.dll+0x10181d]
C [javaw.exe+0x2155]
C [javaw.exe+0x8614]
C [kernel32.dll+0xb729]
Java frames: (J=compiled Java code, j=interpreted, Vv=VM code)
j com.sun.jna.Function.invokeInt(I[Ljava/lang/Object;)I+0
j com.sun.jna.Function.invoke([Ljava/lang/Object;Ljava/lang/Class;)Ljava/lang/Object;+90
j com.sun.jna.Function.invoke(Ljava/lang/Class;[Ljava/lang/Object;Ljava/util/Map;)Ljava/lang/Object;+194
j com.sun.jna.Library$Handler.invoke(Ljava/lang/Object;Ljava/lang/reflect/Method;[Ljava/lang/Object;)Ljava/lang/Object;+344
j $Proxy0.Z_Beep(J)Z+19
j com.rfarrays.bhabs.fingerPrint.main([Ljava/lang/String;)V+84
v ~StubRoutines::call_stub
--------------- P R O C E S S ---------------
Java Threads: ( => current thread )
0x02b10c00 JavaThread "Low Memory Detector" daemon [_thread_blocked, id=1976, stack(0x02dc0000,0x02e10000)]
0x02b0a400 JavaThread "CompilerThread0" daemon [_thread_blocked, id=1280, stack(0x02d70000,0x02dc0000)]
0x02b08c00 JavaThread "Attach Listener" daemon [_thread_blocked, id=1984, stack(0x02d20000,0x02d70000)]
0x02b07800 JavaThread "Signal Dispatcher" daemon [_thread_blocked, id=2160, stack(0x02cd0000,0x02d20000)]
0x02b02400 JavaThread "Finalizer" daemon [_thread_blocked, id=2052, stack(0x02c80000,0x02cd0000)]
0x02afd800 JavaThread "Reference Handler" daemon [_thread_blocked, id=752, stack(0x02c30000,0x02c80000)]
=>0x003a9000 JavaThread "main" [_thread_in_native, id=3832, stack(0x008c0000,0x00910000)]
Other Threads:
0x02afc400 VMThread [stack: 0x02be0000,0x02c30000] [id=1504]
0x02b1b800 WatcherThread [stack: 0x02e10000,0x02e60000] [id=1980]
VM state:not at safepoint (normal execution)
VM Mutex/Monitor currently owned by a thread: None
Heap
def new generation total 4928K, used 2455K [0x22970000, 0x22ec0000, 0x27ec0000)
eden space 4416K, 55% used [0x22970000, 0x22bd5db0, 0x22dc0000)
from space 512K, 0% used [0x22dc0000, 0x22dc0000, 0x22e40000)
to space 512K, 0% used [0x22e40000, 0x22e40000, 0x22ec0000)
tenured generation total 10944K, used 0K [0x27ec0000, 0x28970000, 0x32970000)
the space 10944K, 0% used [0x27ec0000, 0x27ec0000, 0x27ec0200, 0x28970000)
compacting perm gen total 12288K, used 343K [0x32970000, 0x33570000, 0x36970000)
the space 12288K, 2% used [0x32970000, 0x329c5f20, 0x329c6000, 0x33570000)
ro space 10240K, 51% used [0x36970000, 0x36e9ae00, 0x36e9ae00, 0x37370000)
rw space 12288K, 54% used [0x37370000, 0x37a072d8, 0x37a07400, 0x37f70000)
Dynamic libraries:
0x00400000 - 0x00424000 C:\Program Files\Java\jre6\bin\javaw.exe
0x7c900000 - 0x7c9b2000 C:\WINDOWS\system32\ntdll.dll
0x7c800000 - 0x7c8f6000 C:\WINDOWS\system32\kernel32.dll
0x77dd0000 - 0x77e6b000 C:\WINDOWS\system32\ADVAPI32.dll
0x77e70000 - 0x77f03000 C:\WINDOWS\system32\RPCRT4.dll
0x77fe0000 - 0x77ff1000 C:\WINDOWS\system32\Secur32.dll
0x7e410000 - 0x7e4a1000 C:\WINDOWS\system32\USER32.dll
0x77f10000 - 0x77f59000 C:\WINDOWS\system32\GDI32.dll
0x76390000 - 0x763ad000 C:\WINDOWS\system32\IMM32.DLL
0x7c340000 - 0x7c396000 C:\Program Files\Java\jre6\bin\msvcr71.dll
0x6d800000 - 0x6da97000 C:\Program Files\Java\jre6\bin\client\jvm.dll
0x76b40000 - 0x76b6d000 C:\WINDOWS\system32\WINMM.dll
0x6d7b0000 - 0x6d7bc000 C:\Program Files\Java\jre6\bin\verify.dll
0x6d330000 - 0x6d34f000 C:\Program Files\Java\jre6\bin\java.dll
0x6d290000 - 0x6d298000 C:\Program Files\Java\jre6\bin\hpi.dll
0x76bf0000 - 0x76bfb000 C:\WINDOWS\system32\PSAPI.DLL
0x6d7f0000 - 0x6d7ff000 C:\Program Files\Java\jre6\bin\zip.dll
0x68000000 - 0x68036000 C:\WINDOWS\system32\rsaenh.dll
0x77c10000 - 0x77c68000 C:\WINDOWS\system32\msvcrt.dll
0x769c0000 - 0x76a74000 C:\WINDOWS\system32\USERENV.dll
0x5b860000 - 0x5b8b5000 C:\WINDOWS\system32\netapi32.dll
0x6d610000 - 0x6d623000 C:\Program Files\Java\jre6\bin\net.dll
0x71ab0000 - 0x71ac7000 C:\WINDOWS\system32\WS2_32.dll
0x71aa0000 - 0x71aa8000 C:\WINDOWS\system32\WS2HELP.dll
0x71a50000 - 0x71a8f000 C:\WINDOWS\System32\mswsock.dll
0x76f20000 - 0x76f47000 C:\WINDOWS\system32\DNSAPI.dll
0x76d60000 - 0x76d79000 C:\WINDOWS\system32\iphlpapi.dll
0x76fb0000 - 0x76fb8000 C:\WINDOWS\System32\winrnr.dll
0x76f60000 - 0x76f8c000 C:\WINDOWS\system32\WLDAP32.dll
0x76fc0000 - 0x76fc6000 C:\WINDOWS\system32\rasadhlp.dll
0x10000000 - 0x10052000 C:\Documents and Settings\bkonwar\Local Settings\Temp\jna5972695927945545932.tmp
0x03510000 - 0x03546000 C:\WINDOWS\system32\zkemsdk.dll
0x03560000 - 0x03574000 C:\WINDOWS\system32\commpro.dll
0x662b0000 - 0x66308000 C:\WINDOWS\system32\hnetcfg.dll
0x71a90000 - 0x71a98000 C:\WINDOWS\System32\wshtcpip.dll
VM Arguments:
jvm_args: -Dfile.encoding=Cp1252
java_command: com.xyz.bhabs.fingerPrint
Launcher Type: SUN_STANDARD
Environment Variables:
PATH=C:/Program Files/Java/jre6/bin/client;C:/Program Files/Java/jre6/bin;C:/Program Files/Java/jre6/lib/i386;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;;C:\Program Files\Java\jre1.6.0_07\bin;C:\Program Files\Android\android-sdk-windows\tools;C:\Program Files\TortoiseSVN\bin
USERNAME=BKonwar
OS=Windows_NT
PROCESSOR_IDENTIFIER=x86 Family 6 Model 15 Stepping 13, GenuineIntel
--------------- S Y S T E M ---------------
OS: Windows XP Build 2600 Service Pack 3
CPU:total 2 (2 cores per cpu, 1 threads per core) family 6 model 15 stepping 13, cmov, cx8, fxsr, mmx, sse, sse2, sse3, ssse3
Memory: 4k page, physical 2085780k(1286036k free), swap 4024188k(3249652k free)
vm_info: Java HotSpot(TM) Client VM (16.3-b01) for windows-x86 JRE (1.6.0_20-b02), built on Apr 12 2010 13:52:23 by "java_re" with MS VC++ 7.1 (VS2003)
time: Wed May 25 10:02:24 2011
elapsed time: 21 seconds
Regards,
Bhabs
Edited by: 861222 on May 25, 2011 12:19 AM

861222 wrote:
# A fatal error has been detected by the Java Runtime Environment:
# EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x0351fe3b, pid=1664, tid=3832Not much to tell here. This line here looks suspiciously like a null-pointer error happening in the native code. It is impossible to say how, where and why. Go back to your code and start debugging I'd say, see where invalid data can be passed to the native code.

Could not initialize the Java Virtual Machine

While trying to configure the turnkey product I encounter an error in starting the JBoss for Adobe LiveCycle ES v8.0 service. The JBossService.exe ends up showing in the task list - but the service shows its status as "starting" and an enty stating: "Could not initialize the Java Virtual Machine" is placed in the event log. I've seen a posting on this form that traced at least some of these symptoms to the account under which the service is configured to run - but I don't believe that solution applies in this case - I'm starting the service under the System Account which has all the permissions it needs to start the service.

Thanks very much for the suggestion. Indeed, the problem turned out to be memory related - I was able to correct the issue by updating the registry keys "JVM Option Number 4" and "JVM Option Number 5" so specify lower values. For some reason the system didn't like the 1024 meg size that was set by default (our server has 2 gig of memory).

Garbage collection Java Virtual Machine : Hewlett-Packard Hotspot release 1.3.1.01

"Hi,
I try and understand the mechanism of garbage collection of the Java Virtual Machine : Hewlett-Packard Hotspot release 1.3.1.01.
There is description of this mechanism in the pdf file : "memory management and garbage collection" available at the paragraph "Java performance tuning tutorial" at the page :
http://h21007.www2.hp.com/dspp/tech/tech_TechDocumentDetailPage_IDX/1,1701,1607,00.html
Regarding my question :
Below is an extract of the log file of garbage collections. This extract has 2 consecutive garbage collections.
(each begins with "<GC:").
<GC: 1 387875.630047 554 1258496 1 161087488 0 161087488 20119552 0 20119552
334758064 238778016 335544320
46294096 46294096 46399488 5.319209 >
<GC: 5 387926.615209 555 1258496 1 161087488 0 161087488 0 0 20119552
240036512 242217264 335544320
46317184 46317184 46399488 5.206192 >
There are 2 "full garbage collections", one of reason "1" and one of reason "5".
For the first one "Old generation After " =238778016
For the second "Old generation After " =238778016
Thus, "Old generation Before garbage collection" of the second is higher than "Old generation After garbage collection". Why?
I expected all objects to be allocated in the "Eden" space. And therefore I did not expect to s

I agree but my current Hp support is not very good on JVM issues.
Rob Woollen <[email protected]> wrote:
You'd probably be better off asking this question to HP.
-- Rob
Martial wrote:
The object of this mail is the Hewlett-Packard 1.3.1.01 Hotspot JavaVirtual Machine
release and its garbage collection mechanism.
I am interested in the "-Xverbosegc" option for garbage collectionmonitoring.
I have been through the online document :
http://www.hp.com/products1/unix/java/infolibrary/prog_guide/java1_3/hotspot.html#-Xverbosegc
I would like to find out more about the garbage collection mechanismand need
further information to understand the result of the log file generatedwith the
"-Xverbosegc"
For example here is an extract of a garbage collection log file generatedwith
Hewlett-Packard Hotspot Java Virtual Machine. Release 1.3.1.01.
These are 2 consecutive rows of the files :
<GC: 5 385565.750251 543 48 1 161087488 0 161087488 0 0 20119552 264184480255179792
335544320 46118384 46118384 46137344 5.514721 >
<GC: 1 385876.530728 544 1258496 1 161087488 0 161087488 20119552 020119552 334969696
255530640 335544320 46121664 46106304 46137344 6.768760 >
We have 2 full garbage collections, one of Reason 5 and the next oneof Reason
1.
What happened between these 2 garbage collections as we got : "Oldgeneration
After" of row 2 is higher than "Old generation Before" of row 1? Iexpected Objects
to be initially allocated in eden and so we could not get "old generation2modified
between the end of one garbage collection and before the next one.
Could you please clarify this issue and/or give more information aboutgarbage
collection mechanisms with the Hewlett-Packard Hotspot Java VirtualMachine. Release
1.3.1.01.

Start up Error: "Could not create the Java virtual machine"

I downloaded WebLogic Platform 10.3.0.0 (net_server103_win32.exe) and installed it on my Windows Vista laptop.
I am unable to start the server.
From Start menu I selected (WebLogic ServerExamples-->Start Examples Server)
The following output displayed in the console window:
JAVA Memory arguments: -Xms256m -Xmx512m
WLS Start Mode=Development
CLASSPATH=C:\bea\wlserver_10.3\samples\server\examples\build\serverclasses;C:\be
a\patch_wlw1030\profiles\default\sys_manifest_classpath\weblogic_patch.jar;C:\be
a\patch_wls1030\profiles\default\sys_manifest_classpath\weblogic_patch.jar;C:\be
a\patch_cie660\profiles\default\sys_manifest_classpath\weblogic_patch.jar;C:\bea
\JROCKI~1\lib\tools.jar;C:\bea\WLSERV~1.3\server\lib\weblogic_sp.jar;C:\bea\WLSE
RV~1.3\server\lib\weblogic.jar;C:\bea\modules\features\weblogic.server.modules_1
0.3.0.0.jar;C:\bea\WLSERV~1.3\server\lib\webservices.jar;C:\bea\modules\ORGAPA~1
.5/lib/ant-all.jar;C:\bea\modules\NETSFA~1.0_1/lib/ant-contrib.jar;;C:\bea\WLSER
V~1.3\common\eval\pointbase\lib\pbembedded57.jar;C:\bea\WLSERV~1.3\common\eval\p
ointbase\lib\pbclient57.jar;C:\bea\WLSERV~1.3\server\lib\xqrl.jar;;
PATH=C:\bea\patch_wlw1030\profiles\default\native;C:\bea\patch_wls1030\profiles\
default\native;C:\bea\patch_cie660\profiles\default\native;C:\bea\WLSERV~1.3\ser
ver\native\win\32;C:\bea\WLSERV~1.3\server\bin;C:\bea\modules\ORGAPA~1.5\bin;C:\
bea\JROCKI~1\jre\bin;C:\bea\JROCKI~1\bin;C:\Windows\system32;C:\Windows;C:\Windo
ws\System32\Wbem;C:\Program Files\ATI Technologies\ATI.ACE;C:\Program Files\Comm
on Files\Roxio Shared\DLLShared\;C:\Program Files\Common Files\Roxio Shared\DLLS
hared\;C:\Program Files\Common Files\Roxio Shared\9.0\DLLShared\;C:\Program File
s\QuickTime\QTSystem\;C:\Program Files\Java\jre1.6.0\bin;C:\groovy\Groovy-1.5.7\
bin;C:\Sun\SDK\bin;C:\Sun\SDK\jdk\bin;C:\bea\WLSERV~1.3\server\native\win\32\oci
920_8
* To start WebLogic Server, use a username and *
* password assigned to an admin-level user. For *
* server administration, use the WebLogic Server *
* console at http:\\hostname:port\console *
starting weblogic with Java version:
java version "1.6.0_05"
Java(TM) SE Runtime Environment (build 1.6.0_05-b13)
BEA JRockit(R) (build R27.6.0-50_o-100423-1.6.0_05-20080626-2105-windows-ia32, c
ompiled mode)
Starting WLS with line:
C:\bea\JROCKI~1\bin\java -jrockit -Xms256m -Xmx512m -Xverify:none -da -Dplat
form.home=C:\bea\WLSERV~1.3 -Dwls.home=C:\bea\WLSERV~1.3\server -Dweblogic.home=
C:\bea\WLSERV~1.3\server -Dweblogic.management.discover=true -Dwlw.iterativeD
ev= -Dwlw.testConsole= -Dwlw.logErrorsToConsole= -Dweblogic.ext.dirs=C:\bea\patc
h_wlw1030\profiles\default\sysext_manifest_classpath;C:\bea\patch_wls1030\profil
es\default\sysext_manifest_classpath;C:\bea\patch_cie660\profiles\default\sysext
manifestclasspath -Dweblogic.Name=examplesServer -Djava.security.policy=C:\bea
\WLSERV~1.3\server\lib\weblogic.policy weblogic.Server
Could not create the Java virtual machine.
Stopping PointBase server...
PointBase server stopped.
C:\bea\wlserver_10.3\samples\domains\wl_server>
Does anyone have any suggestions on how to troubleshoot this problem?
Thank you,
B. Regan

I do not know how to modify any startup parameters. I am new to WebLogic and downloaded and installed the server for the first time yesterday. I used all of the defaults for the install. To start the server I am using Windows Start menu like this:
Start-->All Programs-->Oracle WebLogic-->WebLogic Server 10gR3-->Examples-->Start Examples Server
A command prompt window opens and the messages I described earlier display in the window.
These were the messages when I used another command window to call the example server domain's bin\setDomainEnv.cmd script and then execute java -version (as suggested in the earlier post):
C:\bea\wlserver_10.3\samples\domains\wl_server>java -version
java version "1.6.0_05"
Java(TM) SE Runtime Environment (build 1.6.0_05-b13)
BEA JRockit(R) (build R27.6.0-50_o-100423-1.6.0_05-20080626-2105-windows-ia32, c
ompiled mode)
I see now that when I go to
Start-->All Programs-->Oracle WebLogic-->WebLogic Server 10gR3-->Examples
that there is an option to "Stop Example Server" When I choose that option another command window opens, a couple of messages scroll by, there's a pause at a "connecting to t3://localhost:7001" then a bunch of message flash by and the command window disappears. So I can't capture the output of that command.
I tried rebooting my laptop but no change in the behavior.
There is some good news. I tried starting the Medical Records Server. That command succeeded. I will see what I can learn through using the Medical Records Server and ignore the Examples Server for now.
Thank you for the suggestions.
B.Regan

Could not create the Java virtual machine

Hello...
This is my jdev version 11.1.1.5.0
When I am running my project i am getting this type of error so what can i do for that
Here is that error:
*** Using port 7101 ***
"C:\Documents and Settings\Administrator\Application Data\JDeveloper\system11.1.1.5.37.60.13\DefaultDomain\bin\startWebLogic.cmd"
[waiting for the server to complete its initialization...]
JAVA Memory arguments: -Xms256m -Xmx512m -XX:CompileThreshold=8000 -XX:PermSize=128m -XX:MaxPermSize=512m
WLS Start Mode=Development
CLASSPATH=C:\Oracle\MIDDLE~1\ORACLE~1\modules\oracle.jdbc_11.1.1\ojdbc6dms.jar;C:\Oracle\MIDDLE~1\patch_wls1035\profiles\default\sys_manifest_classpath\weblogic_patch.jar;C:\Oracle\MIDDLE~1\patch_jdev1111\profiles\default\sys_manifest_classpath\weblogic_patch.jar;C:\Oracle\MIDDLE~1\JDK160~1\lib\tools.jar;C:\Oracle\MIDDLE~1\WLSERV~1.3\server\lib\weblogic_sp.jar;C:\Oracle\MIDDLE~1\WLSERV~1.3\server\lib\weblogic.jar;C:\Oracle\MIDDLE~1\modules\features\weblogic.server.modules_10.3.5.0.jar;C:\Oracle\MIDDLE~1\WLSERV~1.3\server\lib\webservices.jar;C:\Oracle\MIDDLE~1\modules\ORGAPA~1.1/lib/ant-all.jar;C:\Oracle\MIDDLE~1\modules\NETSFA~1.0_1/lib/ant-contrib.jar;C:\Oracle\MIDDLE~1\ORACLE~1\modules\oracle.jrf_11.1.1\jrf.jar;C:\Oracle\MIDDLE~1\WLSERV~1.3\common\derby\lib\derbyclient.jar;C:\Oracle\MIDDLE~1\WLSERV~1.3\server\lib\xqrl.jar;C:\Program Files\Java\jdk1.6.0_16;.;
PATH=C:\Oracle\MIDDLE~1\patch_wls1035\profiles\default\native;C:\Oracle\MIDDLE~1\patch_jdev1111\profiles\default\native;C:\Oracle\MIDDLE~1\WLSERV~1.3\server\native\win\32;C:\Oracle\MIDDLE~1\WLSERV~1.3\server\bin;C:\Oracle\MIDDLE~1\modules\ORGAPA~1.1\bin;C:\Oracle\MIDDLE~1\JDK160~1\jre\bin;C:\Oracle\MIDDLE~1\JDK160~1\bin;D:\app\Administrator\product\11.2.0\dbhome_1\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\Program Files\Java\jdk1.6.0_16\bin;.;;C:\Oracle\MIDDLE~1\WLSERV~1.3\server\native\win\32\oci920_8
* To start WebLogic Server, use a username and   *
* password assigned to an admin-level user. For *
* server administration, use the WebLogic Server *
* console at http:\\hostname:port\console        *
starting weblogic with Java version:
java version "1.6.0_24"
Java(TM) SE Runtime Environment (build 1.6.0_24-b50)
Java HotSpot(TM) Client VM (build 19.1-b02, mixed mode)
Starting WLS with line:
C:\Oracle\MIDDLE~1\JDK160~1\bin\java -client   -Xms256m -Xmx512m -XX:CompileThreshold=8000 -XX:PermSize=128m -XX:MaxPermSize=512m -Dweblogic.Name=DefaultServer -Djava.security.policy=C:\Oracle\MIDDLE~1\WLSERV~1.3\server\lib\weblogic.policy -Djavax.net.ssl.trustStore=C:\Oracle\Middleware\wlserver_10.3\server\lib\DemoTrust.jks -Dweblogic.nodemanager.ServiceEnabled=true -Xverify:none -da -Dplatform.home=C:\Oracle\MIDDLE~1\WLSERV~1.3 -Dwls.home=C:\Oracle\MIDDLE~1\WLSERV~1.3\server -Dweblogic.home=C:\Oracle\MIDDLE~1\WLSERV~1.3\server -Djps.app.credential.overwrite.allowed=true -Dcommon.components.home=C:\Oracle\MIDDLE~1\ORACLE~1 -Djrf.version=11.1.1 -Dorg.apache.commons.logging.Log=org.apache.commons.logging.impl.Jdk14Logger -Ddomain.home=C:\DOCUME~1\ADMINI~1\APPLIC~1\JDEVEL~1\SYSTEM~1.13\DEFAUL~1 -Djrockit.optfile=C:\Oracle\MIDDLE~1\ORACLE~1\modules\oracle.jrf_11.1.1\jrocket_optfile.txt -Doracle.server.config.dir=C:\DOCUME~1\ADMINI~1\APPLIC~1\JDEVEL~1\SYSTEM~1.13\DEFAUL~1\config\FMWCON~1\servers\DefaultServer -Doracle.domain.config.dir=C:\DOCUME~1\ADMINI~1\APPLIC~1\JDEVEL~1\SYSTEM~1.13\DEFAUL~1\config\FMWCON~1 -Digf.arisidbeans.carmlloc=C:\DOCUME~1\ADMINI~1\APPLIC~1\JDEVEL~1\SYSTEM~1.13\DEFAUL~1\config\FMWCON~1\carml -Digf.arisidstack.home=C:\DOCUME~1\ADMINI~1\APPLIC~1\JDEVEL~1\SYSTEM~1.13\DEFAUL~1\config\FMWCON~1\arisidprovider -Doracle.security.jps.config=C:\DOCUME~1\ADMINI~1\APPLIC~1\JDEVEL~1\SYSTEM~1.13\DEFAUL~1\config\fmwconfig\jps-config.xml -Doracle.deployed.app.dir=C:\DOCUME~1\ADMINI~1\APPLIC~1\JDEVEL~1\SYSTEM~1.13\DEFAUL~1\servers\DefaultServer\tmp\_WL_user -Doracle.deployed.app.ext=\- -Dweblogic.alternateTypesDirectory=C:\Oracle\MIDDLE~1\ORACLE~1\modules\oracle.ossoiap_11.1.1,C:\Oracle\MIDDLE~1\ORACLE~1\modules\oracle.oamprovider_11.1.1 -Djava.protocol.handler.pkgs=oracle.mds.net.protocol -Dweblogic.jdbc.remoteEnabled=false -Dwsm.repository.path=C:\DOCUME~1\ADMINI~1\APPLIC~1\JDEVEL~1\SYSTEM~1.13\DEFAUL~1\oracle\store\gmds   -Dweblogic.management.discover=true -Dwlw.iterativeDev= -Dwlw.testConsole= -Dwlw.logErrorsToConsole= -Dweblogic.ext.dirs=C:\Oracle\MIDDLE~1\patch_wls1035\profiles\default\sysext_manifest_classpath;C:\Oracle\MIDDLE~1\patch_jdev1111\profiles\default\sysext_manifest_classpath weblogic.Server
Error occurred during initialization of VM
Could not reserve enough space for object heap
Could not create the Java virtual machine.
Process exited.

Yesterday when i run that project at that time it successful compile and got output.
Today morning when i login in my PC and again i run that project once from there i am getting that massage......

Installation fails with "Cannot launch the Java Virtual Machine"

I'm trying to install OAS 10.1.3.1. on Windows XPbut after copying all the files the installer starts complaining that it cannot lauch the Java Virtual Machine. Eventually, the process gets to the configuration step where it succeeds with one configuration, then fails with the next, and then finally goes into an eternal loop.
When launching the installer it claims that my environment successfully passes all test for memory size, etc.
Is this a known problem? Is there any way I can get more info about the reason why the JVM could not get lauched? I searched for information in the logs without success. I also tried to play around with the PATH environment variable since I saw some installation note saying that includingthe jre/bin path here could help, but it did not help.
Could anyone, please, give me a hint of how to complete the installation successfully?

Thanks for the hint.
I had a look in the INI-file of my BPEL installation and this is what it said about memory:
JRE_MEMORY_OPTIONS=" -mx256m"
Still, if I start the BPEL server it finally comes up after issuing a lot of complaints but as soon as I request a page I get this:
500 Internal Server Error
OracleJSP: oracle.jsp.provider.JspCompileException:
Fel vid kompilering:C:\product\10.1.3.1\OraBPEL_1\bpel\system\appserver\oc4j\j2ee\home\application-deployments\orabpel\console_war\persistence\_pages\\_login.java
Could not create the Java virtual machine.
Error occurred during initialization of VM
Could not reserve enough space for object heapThis is strange since at the time there is >1.4 GB of virtual memory and 0.9 GB of physical memory available.
And according to the task manager:
Commit charge limit = 2728684
Physical memory total = 2096496
I am using Windows XP Professional, version 2002, service pack 2.

JRockit 'could not create the Java virtual machine'

I installed JRockit (build R28.1.4-7-144370-1.6.0_26-20110617-2130-linux-x86_64) on a server SLES11SP1 (x86_64), but I got the following erros when I tried to run java command:
/usr/lib64/jrockit-jdk1.6.0_26-R28.1.4-4.0.1/bin # ./java
[WARN ][codegc ] Could not acquire 64KB of code memory.
[WARN ][codegc ] 0B committed previously.
Could not create the Java virtual machine.
Any idea?

When you do ./java you usually get some output such as:
[oracle@edu-wls-rh bin]$ ./java
Usage: java [-options] class [args...]
           (to execute a class)
   or java [-options] -jar jarfile [args...]
           (to execute a jar file)
where options include:
    -d32          use a 32-bit data model if available
    -d64          use a 64-bit data model if available
    -jrockit      to select the "jrockit" VM
    -client       to select the "client" VM
    -server       to select the "server" VM [synonym for the "jrockit" VM]
                  The default VM is jrockit.
    -cp <class search path of directories and zip/jar files>
    -classpath <class search path of directories and zip/jar files>
                  A : separated list of directories, JAR archives,
                  and ZIP archives to search for class files.
    -D<name>=<value>
                  set a system property
    -verbose[:class|gc|jni]
                  enable verbose output
    -version      print product version and exit
    -version:<value>
                  require the specified version to run
    -showversion print product version and continue
    -jre-restrict-search | -jre-no-restrict-search
                  include/exclude user private JREs in the version search
    -? -help      print this help message
    -X            print help on non-standard options
    -ea[:<packagename>...|:<classname>]
    -enableassertions[:<packagename>...|:<classname>]
                  enable assertions
    -da[:<packagename>...|:<classname>]
    -disableassertions[:<packagename>...|:<classname>]
                  disable assertions
    -esa | -enablesystemassertions
                  enable system assertions
    -dsa | -disablesystemassertions
                  disable system assertions
    -agentlib:<libname>[=<options>]
                  load native agent library <libname>, e.g. -agentlib:hprof
                    see also, -agentlib:jdwp=help and -agentlib:hprof=help
    -agentpath:<pathname>[=<options>]
                  load native agent library by full pathname
    -javaagent:<jarpath>[=<options>]
                  load Java programming language agent, see java.lang.instrument
    -splash:<imagepath>
                  show splash screen with specified imageNote the usage, which means have to use something like: ./java -Xms1024m -Xmx1024m -Xgc:throughput package.MyMainClass

Message "Failed to create Java Virtual Machine" while installing HANA Studio with SP08

Installing HANA Studio with SP08 but getting error as follows:
HANA Version
Errors:
System Info : Win7(32 bit ), 2GB RAM, 500GB HDD

Not same case but related with Java: 32Bit VI Java Virtual Machine error
In this discussion Hanry Banks answers as follows:
1. Did you install using "Run As Administrator"?
2. In your Advanced System Properties, Go to Environment Variables > System Variables
Look for the 'Path' variable. It should include the following values: C:\Program Files\Java\jre6\bin
In the same area, look for the 'JAVA_HOME' variable. It should point to C:\Program Files\Java\jre6
- Can you confirm?
3. Also go Control Panel > Java > Java Control Panel > Java tab > View > User > Path. It should point to C:\Program Files\Java\jre6\bin\javaw.exe .
- How does it look for you?
How much memory is available on your machine as you launch? Go to: Task manager > Performance > Physical Memory > Available (MB)

Java virtual machine shuts down

When a Java virtual machine shuts down abruptly (e.g. user type ^C or user logoff), does the Java virtual machine execute the finalize() method of all the objects in the heap?
If not, could you please tell me where should I put the cleanup code of my application so that they will get execute even when the Java virtual machine shuts down abruptly?
Thank you.

...execute the finalize() method of all the objects in the heap? It shouldn't matter, because you shouldn't be doing anything in a finalizer anyways. Any resource that is not memory should be explicitly cleaned up (not using a finalizer.) And if it is just memory then it doesn't matter if it is cleaned or not - it all gets returned to the OS.
There is ABSOLUTELY NO GUARANTEE that a finalizer will even be called. The only thing the specification says is that if it is called that it will only be called once.
And if you don't believe me then feel free to search the forums for the other numerous threads and respondants that say the same thing. And the bug lists that demonstrate how finalizers are not called on normal exits.
So once you rework your design/code to stop relying on those pesky finalizers, if you still have some clean up that needs to occur on a clean application exit then you can use Runtime.addShutDownHook().

How to increase java virtual machine.. i am using Ocj4 server

How to increase memory size java virtual machine.. i am using Ocj4 server
Edited by: java_net on Aug 29, 2008 4:09 PM

Google ( [oc4j heap size|http://www.google.com/search?q=oc4j+heap+size] )

Install of SAP HANA Studio Dev Ed v1.00.80 fails with "Could not create the Java Virtual Machine"

Hello,
Scope: JVM error during initial install of SAP HANA Studio Developer Edition v1.00.80, Win86/32bit
Source: installation files pulled from HANA Studio tab at https://hanadeveditionsapicl.hana.ondemand.com/hanadevedition/, which is a link from the main HANA site of http://scn.sap.com/community/developer-center/hana. zip folder: "sap_hana_win32_studio_rev80"
Targeted O/S: Windows 7, 32-bit, local Java is SE 7, update 67.   Java environment has been confirmed via checks provided at http://www.java.com/en/download/manual.jsp
Actions taken:
Attempted to update the installation's eclipse.ini file by reducing the -Xmx value; see details below.
Read thru postings such as http://scn.sap.com/thread/3390626 and the threads it recommended.
Checked OSS (ie Note 1859686 - HANA Studio does not start)
Description of installation error:
Shortly after executing "hdbinst", it fails with the error "Could not create the Java Virtual Machine". I've verified that there is nearly 3G of memory free. What I did notice, as shown in the attached files, is that Eclipse is part of this installation and it's pre-loaded with the "eclipse.ini". I firmly believe the solution could be to reduce parameter "-Xmx1024m" to "-Xmx512m" but it's a catch-22 because even after updating eclipse.ini (in installation folder C:\Program Files\SAP\hdbstudio\tmp_p2director2014.08.13_13.36.44\director), the install program requires that the "hdbstudio" folder to be empty upon restarting it.
Since the installation is basically a package with a lot of .jar files, there is no eclipse.ini file available in the source install folder; otherwise, updating it there would be the easiest solution if that option were available. The file is only available in the targeted deployment folder above.
If you have encountered this same error and were able to resolve it, I would be grateful to know of your solution. Thanks very much.
FYI: the HANA Client installed with no issues.
Jim Cleek
FYI: the images below reflect the sequence of images produced during the installation.
after clicking OK above, the screen below gets updated (see the "is not empty" msg).
Below is the eclipse.ini file located in the deployed/target folder:
Message was edited by: Jim Cleek
FYI: Using information from the SAP HANA Database - Studio Installation and Update Guide, I tried to override the installation's use of its eclipse.ini file by passing my own modified version (with "-Xmx512m") of that file that was placed in a separate folder. The cmd used via DOS window was "hdbsetup.exe -a studio --configfile=C:\Users\Admin\Downloads\eclipse.ini" and even though it successfully launched the SAP HANA Lifecycle Management gui, it failed on the first step with the same JVM create error as above because it appears to have used its own eclipse.ini file, which has "-Xmx1024m".

Update: a message was opened with SAP but unfortunately they could not provide a resolution for this particular scenario. They admitted that the eclipse.ini file cannot be updated since it is bundled as part of the installation package. One point to make that I did not make before was that this was being attempted on an Oracle VirtualBox (4.3.10); the SAP HANA contact said he assumed that SAP has not tested this particular scenario, thus it could not be supported.
Resolution: the end result was to abort trying to install SAP HANA Client and Studio on the Oracle VirtualBox but to install it locally on my own desktop, which runs on Windows 7 Enterprise 64-bit with 8G of memory. The SAP HANA files below were downloaded, extracted and installed successfully in the order shown.
FYI: the Studio installation detected that a 64-bit version of Java was not installed so I installed that and then adjusted the User environmental variable JAVA_HOME to point to that new path, leaving the System variable still pointing to the pre-existing 32-bit Java path.
SAPCAR 7.20 -> Windows on x64 64bit: SAPCAR_315-20010453.EXE
IMDB_CLIENT100_80_0-10009664.SAR   Revision 80 for SAP HANA CLIENT 1.00
Support Package SAP HANA CLIENT 1.00 Windows on x64 64bit
IMC_STUDIO100_80_0-20007647.SAR   Revision 80 for SAP HANA STUDIO 1.00
Support Package SAP HANA STUDIO 1.00 Windows on x64 64bit
jre-7u67-windows-x64.exe - http://www.oracle.com/technetwork/java/javase/downloads/jre7-downloads-1880261.html
Jim Cleek
HP Enterprise Services

IDM's config.sh failed on "Could not create the Java virtual machine"

I have OL5.7 32bit(Oracle Linux) set 2.5GB RAM. Installed rcu11.1.1.5's schemas, wls10.3.5, idm11.1.1.2.0 and patched to tdm11.1.1.5.0
I tried to configure IDM's components OID, OVD and ODSM and to create the domain for these.
ORACLE_HOME=/u01/app/oracle/FM/Oracle_IDM1
<ORACLE_HOME>/bin/config.sh
error msg:
>
[oracle@buoel57 bin]$ ./config.sh
Starting Fusion Middleware Configuration Wizard
ORACLE_HOME set as /u01/app/oracle/FM/Oracle_IDM1
PATH set as /u01/app/oracle/FM/Oracle_IDM1/bin:/usr/kerberos/bin:/usr/local/bin:/bin:/usr/bin:/home/oracle/bin:/home/oracle/bin
LD_LIBRARY_PATH set as /u01/app/oracle/FM/Oracle_IDM1/lib
Starting Oracle Universal Installer...
Checking swap space: must be greater than 500 MB. Actual 4191 MB Passed
Checking monitor: must be configured to display at least 256 colors. Actual 65536 Passed
Preparing to launch Oracle Universal Installer from /tmp/OraInstall2011-11-24_10-07-38AM. Please wait ...[oracle@buoel57 bin]$
Error occurred during initialization of VM
Could not reserve enough space for object heap
Could not create the Java virtual machine.
[oracle@buoel57 bin]$
>
Java info
>
[oracle@buoel57 bin]$ which java
/u01/app/oracle/FM/jdk160_24/bin/java
[oracle@buoel57 bin]$ java -version
java version "1.6.0_24"
Java(TM) SE Runtime Environment (build 1.6.0_24-b50)
Java HotSpot(TM) Client VM (build 19.1-b02, mixed mode)
[oracle@buoel57 bin]$
>
Where should I start to look?
The log as follow, no much info
>
[oracle@buoel57 logs]$ more installActions2011-11-24_12-04-36PM.log
The file oraparam.ini could not be found at /u01/app/oracle/FM/Oracle_IDM1/bin/../oui/bin/oraparam.ini
Using paramFile: /u01/app/oracle/FM/Oracle_IDM1/oui/oraparam.ini
Checking swap space: must be greater than 500 MB. Actual 4191 MB Passed
Checking monitor: must be configured to display at least 256 colors. Actual 65536 Passed
The number of files bootstrapped for the jre is 699.
The number of files bootstrapped for the oui is 100.
Using the umask value '027' available from oraparam.ini
Execvp of the child jre : the cmdline is /tmp/OraInstall2011-11-24_12-04-36PM/jre/bin/java, and the argv is
/tmp/OraInstall2011-11-24_12-04-36PM/jre/bin/java
-Doracle.installer.library_loc=/tmp/OraInstall2011-11-24_12-04-36PM/oui/lib/linux
-Doracle.installer.oui_loc=/tmp/OraInstall2011-11-24_12-04-36PM/oui
-Doracle.installer.bootstrap=TRUE
-Doracle.installer.startup_location=/u01/app/oracle/FM/Oracle_IDM1/oui/bin
-Doracle.installer.jre_loc=../../jre
-Doracle.installer.nlsEnabled="TRUE"
-Doracle.installer.prereqConfigLoc=/tmp/OraInstall2011-11-24_12-04-36PM/prereq
-Doracle.installer.unixVersion=2.6.32-200.13.1.el5uek
-mx1024m
-XX:MaxPermSize=1024m
-cp
/tmp/OraInstall2011-11-24_12-04-36PM::/tmp/OraInstall2011-11-24_12-04-36PM/ext/jlib/enginehelp.jar:/tmp/OraInstall2011-11-24_12-04-3
6PM/ext/jlib/dms.jar:/tmp/OraInstall2011-11-24_12-04-36PM/ext/jlib/commonutils.jar:/tmp/OraInstall2011-11-24_12-04-36PM/ext/jlib/mes
sage.jar:/tmp/OraInstall2011-11-24_12-04-36PM/ext/jlib/glassfish.jaxb.xjc_1.2.0.0_2-1-7.jar:/tmp/OraInstall2011-11-24_12-04-36PM/ext
lib/ojmisc.jar:/tmp/OraInstall2011-11-24_12-04-36PM/oui/jlib/xml.jar:/tmp/OraInstall2011-11-24_12-04-36PM/oui/jlib/srvm.jar:/tmp/Ora
Install2011-11-24_12-04-36PM/oui/jlib/classes12.jar
oracle.sysman.oio.oioc.OiocOneClickInstaller
UnixGroups="{oinstall,dba,}"
-scratchPath
/tmp/OraInstall2011-11-24_12-04-36PM
-sourceType
network
-timestamp
2011-11-24_12-04-36PM
-weblogicConfig
ORACLE_HOME=/u01/app/oracle/FM/Oracle_IDM1
-invPtrLoc
/u01/app/oracle/FM/Oracle_IDM1/oraInst.loc
-oneclick
-Doracle.config.mode=true
[oracle@buoel57 logs]$
[oracle@buoel57 logs]$

Looks like you do not have enough free memory to create the 1GB Java VM you are trying to create. Have you checked that the server has enough free RAM?

JDeveloper: Unable to create an instance of the Java Virtual Machine

Hi,
I've got this
Unable to create an instance of the Java Virtual Machine Located in path: C:\u01\app\Oracle\Middleware\JDev11g\jdk160_21\jre\bin\client\jvm.dll
problem like many people else who use JDeveloper.
The OS is Windows XP, I've got 4G memory but maybe just 3G of it works.
But this is not the problem, because I've searched this problem on internet for days.
I did try to modify the number of
MaxPermSize in jdev.conf
and
Xmx and Xms in ide.conf
I've tried several combinations, and sometimes it works.
The disappoint fact is that even with the same combination of the settings, sometimes it works and sometimes it doesn't.
Sometimes it just work....
Sometimes it just doesn't work....
Sometimes it doesn't...and after rebooting it works again......
Sometimes even rebooting doesn't help.......
Sometimes when change MaxPermSize to a smaller number it works...and next time it may not work again....
Sometimes you change the MaxPermSize to some other number, save, and then change it back,,,,and it works again.....
but next time you try to use it, it may not work..........again....
I don't know what leads to these problems.....anyone could help, please?
Thanks in advance....

having mentioned that you have tried all possible options. can u try to change the jdk??

Jvm-java virtual machine

Hai iam new to this forum and as well i just started to learn java iwant to know in brief about JVM
i think it may be silly question but as i am bigginer to java kindly expect reply

georgemc wrote:
faustofrancis wrote:
A Java Virtual Machine (JVM) is a set of computer software programs and data structures which use a virtual machine model for the execution of other computer programs and scripts. The model used by a JVM accepts a form of computer intermediate language commonly referred to as Java bytecode. This language conceptually represents the instruction set of a stack-oriented, capability architecture.
Java Virtual Machines operate on Java bytecode, which is normally (but not necessarily) generated from Java source code; a JVM can also be used to implement programming languages other than Java. For example, Ada source code can be compiled to Java bytecode, which may then be executed by a JVM. JVMs can also be released by other companies besides Sun (the developer of Java) -- JVMs using the "Java" trademark may be developed by other companies as long as they adhere to the JVM specification published by Sun (and related contractual obligations).
The JVM is a crucial component of the Java Platform. Because JVMs are available for many hardware and software platforms, Java can be both middleware and a platform in its own right  hence the expression "write once, run anywhere." The use of the same bytecode for all platforms allows Java to be described as "compile once, run anywhere", as opposed to "write once, compile anywhere", which describes cross-platform compiled languages. The JVM also enables such unique features as Automated Exception Handling which provides 'root-cause' debugging information for every software error (exception) independent of the source code.
The JVM is distributed along with a set of standard class libraries which implement the Java API (Application Programming Interface). The virtual machine and API have to be consistent with each other[dubious  discuss] and are therefore bundled together as the Java Runtime Environment.
Execution environment
Programs intended to run on a JVM must be compiled into a standardized portable binary format, which typically comes in the form of .class files. A program may consist of many classes in different files. For easier distribution of large programs, multiple class files may be packaged together in a .jar file (short for Java archive).
The JVM runtime executes .class or .jar files, emulating the JVM instruction set by interpreting it, or using a just-in-time compiler (JIT) such as Sun's HotSpot. JIT compiling, not interpreting, is used in most JVMs today to achieve greater speed. Ahead-of-time compilers that enable the developer to precompile class files into native code for a particular platform also exist.
Like most virtual machines, the Java Virtual Machine has a stack-based architecture.
Although the JVM was primarily aimed at running compiled Java programs, other languages can now run on top of it[1], such as:
* Ruby, with JRuby
* JavaScript, with Rhino
* Python, with Jython
* Common Lisp, with Armed Bear Common Lisp
* Groovy
* Scala
[edit] Bytecode verifier
A basic philosophy of Java is that it is inherently "safe" from the standpoint that no user program can "crash" the host machine or otherwise interfere inappropriately with other operations on the host machine, and that it is possible to protect certain functions and data structures belonging to "trusted" code from access or corruption by "untrusted" code executing within the same JVM. Furthermore, common programmer errors that often lead to data corruption or unpredictable behavior such as accessing off the end of an array or using an uninitialized pointer are not allowed to occur. Several features of Java combine to provide this safety, including the class model, the garbage-collected heap, and the verifier.
The JVM verifies all bytecode before it is executed. This verification consists primarily of three types of checks:
* Branches are always to valid locations
* Data is always initialized and references are always type-safe
* Access to "private" or "package private" data and methods is rigidly controlled.
The first two of these checks take place primarily during the "verification" step which occurs when a class is loaded and made eligible for use. The third is primarily performed dynamically, when data items or methods of a class are first accessed by another class.
The verifier permits only some bytecode sequences in valid programs, e.g. a jump (branch) instruction can only target an instruction within the same function or method. Because of this, the fact that JVM is a stack architecture does not imply a speed penalty for emulation on register-based architectures when using a JIT compiler. In the face of the code-verified JVM architecture, it makes no difference to a JIT compiler whether it gets named imaginary registers or imaginary stack positions that need to be allocated to the target architecture's registers. In fact, code verification makes the JVM different from a classic stack architecture whose efficient emulation with a JIT compiler is more complicated and typically carried out by a slower interpreter.
Code verification also ensures that arbitrary bit patterns cannot get used as an address. Memory protection is achieved without the need for a MMU. Thus, JVM is an efficient way of getting memory protection on simple architectures that lack an MMU. This is analogous to managed code in Microsoft's .NET CLR, and conceptually similar to capability architectures such as the Plessey 250, and IBM System/38.
[edit] Bytecode instructions
Main article: Java bytecode
The JVM has instructions for the following groups of tasks:
* Load and store
* Arithmetic
* Type conversion
* Object creation and manipulation
* Operand stack management (push / pop)
* Control transfer (branching)
* Method invocation and return
* Throwing exceptions
* Monitor-based concurrency
The aim is binary compatibility. Each particular host operating system needs its own implementation of the JVM and runtime. These JVMs interpret the byte code semantically the same way, but the actual implementation may be different. More complicated than just the emulation of bytecode is compatible and efficient implementation of the Java core API which has to be mapped to each host operating system.
[edit] Secure execution of remote code
A virtual machine architecture allows very fine-grained control over the actions that code within the machine is permitted to take. This is designed to allow safe execution of untrusted code from remote sources, a model used by Java applets. Applets run within a VM incorporated into a user's browser, executing code downloaded from a remote HTTP server. The remote code runs in a restricted "sandbox", which is designed to protect the user from misbehaving or malicious code. Publishers can purchase a certificate with which to digitally sign applets as "safe", giving them permission to ask the user to break out of the sandbox and access the local file system and network...
[edit] C to bytecode compilers
From the point of view of a compiler Java bytecode is just another processor with an instruction set for which code can be generated. The JVM was originally designed to execute programs written in the Java language. However, the JVM provides an execution environment in the form of a bytecode instruction set and a runtime system that is general enough that it can be used as the target for compilers of other languages.
Because of its close association with Java the JVM performs the runtime checks mandated by the Java specification. This can make it technically difficult to translate C code (which is much more lax with regard to runtime checking) to the JVM and expect it to run without issuing any warnings.
Compilers targeting many different languages, including Ada and COBOL, have been written.
[edit] Licensing
Starting with J2SE 5.0, changes to the JVM specification have been developed under the Java Community Process as JSR 924[2]. As of 2006, changes to specification to support changes proposed to the class file format (JSR 202[3]) are being done as a maintenance release of JSR 924. The specification for the JVM is published in book form,[4] known as "blue book". The preface states:
We intend that this specification should sufficiently document the Java Virtual Machine to make possible compatible clean-room implementations. Sun provides tests which verify the proper operation of implementations of the Java Virtual Machine.
Sun's JVM is called HotSpot. Clean-room Java implementations include Kaffe and IBM J9. Sun retains control over the Java trademark, which it uses to certify implementation suites as fully compatible with Sun's specification.
[edit] See also
* HotSpot, Sun's Virtual Machine
* Da Vinci Machine, a starting Sun project aiming to prototype the extension of the JVM to add support for dynamic languages.
* List of Java virtual machines
* Automated Exception Handling
* Common Language Runtime
* Parrot virtual machine
* Java bytecode
* Class (file format)
* Java performance
* List of compilers
[edit] Notes
1. ^ Tolksdorf, Robert (2005). Languages for the Java VM. Retrieved on 2008-04-23.
2. ^ JSR 924  Specifies changes to the JVM specification starting with J2SE 5.0
3. ^ JSR 202  Specifies a number of changes to the class file format
4. ^ The Java Virtual Machine Specification (the first and second editions are also available online)
[edit] References
* Clarifications and Amendments to the Java Virtual Machine Specification, Second Edition includes list of changes to be made to support J2SE 5.0 and JSR 45
* JSR 45  Specifies changes to the class file format to support source-level debugging of languages such as JSP and SQLJ that are translated to Java
[edit] External links
* The Java Virtual Machine Specification
* Java-Virtual-Machine.net - All about Java Virtual Machines!
* List of languages which compile to the Java virtual machine.
* A decade after Java arrived, there have been improvements in the runtime performance of platform-independent virtual-machine based software.
* Kaffe.org - the Kaffe project
* JamVM - The Jam Virtual Machine
* The lean, mean, virtual machine - An introduction to the basic structure and functionality of the Java Virtual Machine
* Java Glossary - installing Java useful tips for installing Java for users and developers
* Test your Java Virtual Machine
* A list of Java VM-s used in mobile devices
* More Languages for the JVM
* Sun to build virtual machine for iPhone - ComputerWorldAre you aware that Wikipedia has ripped off your post?not yet?
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Java virtual machine memory

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