Working as an Application System admin, I need to work very closely with Weblogic and JBoss. Since JBoss runs mostly on JDK versions, Weblogic has one more jdk available called JRocket.
Most of the production servers contains Weblogic will be running on JRocket jvm since it provides some benefits that normal jdk. In this article we will see how we can communicate with Weblogic serer that started using JRocket jvm (thinking that the Weblogic is running on JRocket Jvm).
There is a tool called “jrcmd” provided with JRocket jdk which sends commands to the JRocket jvm. This is a command line tool available in the JRcoket/bin/.Considering the process ID for Weblogic is 3448.Here are a list of commands used with “jrcmd” for communicating with the Weblogic process.
1. Find the Version of the JRocket Running
jrcmd 3448 version
3448:
Oracle JRockit(R) build R28.2.3-13-149708-1.6.0_31-20120327-1522-linux-ia32, compiled mode
GC mode: Garbage collection optimized for throughput, strategy: genparpar
2. Find the available Weblogic process running
jrcmd -p
4536 jrockit.tools.jrcmd.JrCmd -p
3448 weblogic.Server
3. Find the Commands provided by this version
jrcmd 3448 help
3448:
The following commands are available:
kill_management_server
start_management_server
print_object_summary
memleakserver
print_class_summary
print_codeblocks
dump_codelayout
dump_codelist
dump_codemap
print_codegenlist
exception_trace_filter
print_vm_state
print_utf8pool
check_flightrecording
dump_flightrecording
stop_flightrecording
start_flightrecording
print_properties
hprofdump
print_threads
datadump_request
runsystemgc
runfinalization
heap_diagnostics
oom_diagnostics
print_exceptions
version
timestamp
command_line
sanity
verbosity
set_filename
help
print_memusage
set_vmflag
list_vmflags
For more information about a specific command use 'help
Parameters to commands are optional unless otherwise stated.
If you need to find more about a command we can use,
jrcmd 3448 help runsystemgc
3448:
Calls java.lang.System.gc().
full - do a full GC (same as -XXfullsystemgc). (bool, false)
fullcompact - force a full compaction (only for full GCs). (bool,
true)
4. Find Out the Current Time Stamp and Up time of the VM
jrcmd 3448 timestamp
3448:
==== Timestamp ==== uptime: 0 days, 01:35:06 time: Tue Jul 17 14:36:25 2012
5. Find out the Command line and other information used to start the VM Instance
jrcmd 3448 print_vm_state
3448:
Uptime : 0 days, 01:30:57 on Tue Jul 17 14:32:16 2012
Version : Oracle JRockit(R) R28.2.3-13-149708-1.6.0_31-20120327-1522-linux-ia32
CPU : Intel Core 2 SSE SSE2 SSE3 SSSE3 SSE4.1 Core Intel64
Number CPUs : 2
Tot Phys Mem : 3179118592 (3031 MB)
OS version : Red Hat Enterprise Linux Server release 5.6 (Tikanga)
Linux version 2.6.18-238.el5 (mockbuild@ls20-bc2-13.build.redhat.com) (gcc version 4.1.2 20080704 (Red Hat 4.1.2-50)) #1 SMP Sun Dec 19 14:24:47 EST 2010 (i686)
.
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6. Find out the Command line of a VM Instance
jrcmd 3448 command_line
3448:
Command Line: -Xms512m -Xmx512m -Dweblogic.Name=AdminServer Djava.security.policy=/soa/wls10/Middleware/wlserver_10.3/server/lib/
weblogic.policy Dweblogic.ProductionModeEnabled=true -da -Dplatform.home=/soa/wls10/Middleware/wlserver_10.3 -Dwls.home=/soa/wls10/Middleware/wlserver_10.3/server Dweblogic.home=/soa/wls10/Middleware/wlserver_10.3/server Dweblogic.management.discover=true -Dwlw.iterativeDev=false -Dwlw.testConsole=false -Dwlw.logErrorsToConsole=false Dweblogic.ext.dirs=/soa/wls10/Middleware/patch_wls1036/profiles/default/
sysext_manifest_classpath:/soa/wls10/Middleware/patch_oepe180/profiles/
default/sysext_manifest_classpath:/soa/wls10/Middleware/patch_ocp371/
profiles/default/sysext_manifest_classpath:/soa/wls10/Middleware/
patch_adfr1111/profiles/default/sysext_manifest_classpath -Dsun.java.command=weblogic.Server Dsun.java.launcher=SUN_STANDARD weblogic.Server
7. Find out the Properties available to the VM Instance
jrcmd 3448 print_properties
3448:
=== Initial Java properties: ===
java.vm.specification.name=Java Virtual Machine Specification
java.vm.vendor.url.bug=http://download.oracle.com/docs/cd/E15289_01/
go2troubleshooting.html
weblogic.home=/soa/wls10/Middleware/wlserver_10.3/server
wlw.iterativeDev=false
java.home=/soa/jrockit-jdk1.6.0/jre
java.vm.vendor.url=http://www.oracle.com/
weblogic.ext.dirs=/soa/wls10/Middleware/patch_wls1036/profiles/default/
sysext_manifest_classpath:/soa/wls10/Middleware/patch_oepe180/profiles/
default/sysext_manifest_classpath:/soa/wls10/Middleware/patch_ocp371/
profiles/default/sysext_manifest_classpath:/soa/wls10/Middleware/
patch_adfr1111/profiles/default/sysext_manifest_classpath
java.security.policy=/soa/wls10/Middleware/wlserver_10.3/server/lib/
weblogic.policy
wlw.testConsole=false
java.vm.specification.version=1.0
.
.
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8. Find Out the memory Details
jrcmd 3448 print_memusage scale=M baseline
3448:
Total mapped 773MB (reserved=0MB)
- Java heap 512MB (reserved=0MB)
- GC tables 17MB
- Thread stacks 15MB (#threads=36)
- Compiled code 8MB (used=7MB)
- Internal 0MB
- OS 72MB
- Other 73MB
- Java class data 72MB (malloced=72MB #102209 in 18503 classes)
- Native memory tracking 1MB (malloced=0MB #8)
9. Find out the Object Details
jrcmd 3448 print_object_summary
3448:
--------- Detailed Heap Statistics: ---------
29.9% 10418k 106949 +10418k [C
7.8% 2703k 115352 +2703k java/lang/String
5.8% 2023k 18501 +2023k java/lang/Class
4.6% 1614k 13769 +1614k [Ljava/lang/Object;
4.0% 1388k 15207 +1388k [Ljava/util/HashMap$Entry;
3.8% 1326k 6590 +1326k [B
3.5% 1227k 1059 +1227k [J
2.5% 877k 37435 +877k java/util/HashMap$Entry
2.5% 877k 28076 +877k java/util/LinkedHashMap$Entry
1.6% 541k 17328 +541k java/util/concurrent/ConcurrentHashMap$Segment
1.5% 522k 3347 +522k [I
1.3% 446k 5398 +446k [Ljava/lang/String;
1.2% 432k 18444 +432k java/util/Hashtable$Entry
1.2% 425k 9085 +425k java/util/HashMap
1.2% 407k 17385 +407k java/util/concurrent/locks/ReentrantLock$NonfairSync
1.2% 403k 17236 +403k javax/xml/namespace/QName
1.1% 387k 8267 +387k java/lang/ref/SoftReference
1.1% 370k 17328 +370k [Ljava/util/concurrent/ConcurrentHashMap$HashEntry;
0.9% 326k 5974 +326k java/util/LinkedHashMap
0.9% 324k 5938 +324k com/bea/staxb/buildtime/internal/bts/QNameProperty
0.9% 313k 8037 +313k java/lang/ref/WeakReference
0.9% 311k 4443 +311k [Ljava/util/Hashtable$Entry;
0.8% 278k 17817 +278k com/bea/staxb/buildtime/internal/bts/MethodName
0.8% 276k 3538 +276k java/lang/reflect/Method
34866kB total ---
--------- End of Detailed Heap Statistics ---
10. Find Information Regarding Loaded Class Details
jrcmd 3448 print_class_summary
**class sun/jkernel/DownloadManager$2$2
**class sun/jkernel/DownloadManager$2$1
*class jrockit/vm/RNI
*class jrockit/vm/Reflect
*class jrockit/vm/VM
**class jrockit/vm/Locks
*class jrockit/vm/AccessController
*class java/lang/reflect/AccessibleObject
**class java/lang/reflect/Constructor
**class java/lang/reflect/Field
**class java/lang/reflect/Method
*
*
*
11. Run Garbage Collection
jrcmd 3448 help runsystemgc
3448:
Calls java.lang.System.gc().
full - do a full GC (same as -XXfullsystemgc). (bool, false)
fullcompact - force a full compaction (only for full GCs). (bool,
true)
12. Run Finalization
jrcmd 3448 help runfinalization
3448:
Calls java.lang.System.runFinalization().
13. Generate a Thread Dump
jrcmd 3448 print_threads
14. Heap_diagnostics
This can used in getting detailed information about the heap usage. When this command is executed a full GC is trigged during which the information is collected. The output normally contains 3 sections,
General Information: available memory and heap usage
Detailed heap Details : list the amount of heap that a particular class occupy, the amount of memory in Kbs that they consume, the total number of instances alive and other more information
Reference object statistics – lists the amount of total instances, how many instances are reachable, how many instances are unreachable and thus eligible for garbage collection, how many reference objects were found unreachable during this garbage collection, how many objects were activated before this garbage collection, how many instances are pointing to null and the instance types.
We can run the command like, jrcmd 3448 heap_diagnostics > /logs/heap.conf
If we are interested in a septic class, we can use
jrcmd heap_diagnostics | grep '%.*GenericClassLoader : This will grep for the one line we are interested in. The output seems to be
0.0% 10k 150 +10k weblogic/utils/classloaders/GenericClassLoader
15. Oom_diagnostics
This allows to print the current state of heap when an Out of memory occurs. We can add the following variables to the startup files like
jrcmd 3448 oom_diagnostics > /logs/oos.conf
More to Come, happy learning
