Check Java Process Performance and statistics in Linux

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In Linux, we are using the ps command to check process information and to check machine's performance we use top command. But some times, in case of java processes, we need more information. These commands are not sufficient to get that much of information of particular java process.

Depends on your requirement you can use following commands to get required information of particular java processes.  Jstat, Jmap, Jinfo commands are very useful to analyze to java process performance as well as memory mapping.

Jstat Command

Jstat command is a Java virtual machine statistics monitoring tool. Please see below example for how to use command and its output.

Jstat -gc <PID>

root@Hello:~# jstat -gc 9020

S0C S1C S0U S1U EC EU OC OU PC PU YGC YGCT FGC FGCT GCT

6912.0 6528.0 16.0 0.0 117632.0 108377.4 393216.0 7188.1 17280.0 17262.5 24 0.103 0 0.000 0.103

root@Hello:~# jstat -class 9020

Loaded Bytes Unloaded Bytes Time

3284 3939.7 0 0.0 2.26

There are many options for this command you can use man page for getting all options of this command. For better understanding of jstat output short forms like S0C, S1C click on this link. Jstat Command in Linux.

Jmap Command

Jmap is used to check memory mapping of particular java process. Jmap can give memory mapping of class wise of that java program as well. We can use this command as follows:

usage of this command as

jmap <OPTONS> <PID>

or

jmap <PID>

root@Hello:~# jmap 9020

Attaching to process ID 9020, please wait...

Debugger attached successfully.

Server compiler detected.

JVM version is 20.0-b12

using thread-local object allocation.

Parallel GC with 2 thread(s)

Heap Configuration:

MinHeapFreeRatio = 40

MaxHeapFreeRatio = 70

MaxHeapSize = 536870912 (512.0MB)

NewSize = 1048576 (1.0MB)

MaxNewSize = 4294901760 (4095.9375MB)

OldSize = 4194304 (4.0MB)

NewRatio = 3

SurvivorRatio = 8

PermSize = 16777216 (16.0MB)

MaxPermSize = 134217728 (128.0MB)

Heap Usage:

PS Young Generation

Eden Space:

capacity = 120455168 (114.875MB)

used = 115808768 (110.44384765625MB)

free = 4646400 (4.43115234375MB)

96.14263125680087% used

From Space:

capacity = 7077888 (6.75MB)

used = 16384 (0.015625MB)

free = 7061504 (6.734375MB)

0.23148148148148148% used

To Space:

capacity = 6684672 (6.375MB)

used = 0 (0.0MB)

free = 6684672 (6.375MB)

0.0% used

PS Old Generation

capacity = 402653184 (384.0MB)

used = 7360656 (7.0196685791015625MB)

free = 395292528 (376.98033142089844MB)

1.8280386924743652% used

PS Perm Generation

capacity = 17694720 (16.875MB)

used = 17676760 (16.857872009277344MB)

free = 17960 (0.01712799072265625MB)

99.8985007957176% used

Another use of this jmap command to check all java classes as :

root@Hello:~# jmap -permstat 9020

Attaching to process ID 9020, please wait...

Debugger attached successfully.

Server compiler detected.

JVM version is 20.0-b12

9569 intern Strings occupying 747072 bytes.

finding class loader instances ..Finding object size using Printezis bits and skipping over...

Finding object size using Printezis bits and skipping over...

done.

computing per loader stat ..done.

please wait.. computing liveness....liveness analysis may be inaccurate ...

class_loader classes bytes parent_loader alive? type

<bootstrap> 1673 7167072 null live <internal>

0x94c0ac88 1 1800 0x9464a2d0 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94b4d988 1 1768 null dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94ad3738 1 1800 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94c0ab70 1 1168 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x945e09f0 98 607840 0x945e0a38 live sun/misc/Launcher$AppClassLoader@0x8c775510

0x9485b068 1 1784 null dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94c110b8 1 1768 null dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94c0abe0 1 1768 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94a3cf38 1 1168 null dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x945e0960 720 3903736 0x945e09a8 live org/apache/catalina/loader/StandardClassLoader@0x8cb28578

0x94c0a8d0 1 1808 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94c0ac18 1 1800 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94ad5090 1 1808 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x9488bb88 171 890600 0x945f97d0 live org/apache/catalina/loader/WebappClassLoader@0x8cee3928

0x94ad53a0 1 1800 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94c0a940 1 1768 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94857948 1 1784 null dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94ad2d80 1 1800 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94c0a978 1 1768 null dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94c11c58 1 1800 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94c0aac8 1 1800 0x9464a2d0 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94c0a860 1 1768 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94c0aa58 1 1168 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94ad1748 1 1800 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94ad1128 1 1800 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94c0a9e8 1 1800 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94ad3a48 1 1800 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94c0ab38 1 1800 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94852000 2 24344 null dead javax/management/remote/rmi/NoCallStackClassLoader@0x8ca81c88

0x94c0acc0 1 1808 0x9464a2d0 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94ad59c0 1 1800 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94c0aa20 1 1816 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94c0a908 1 1800 0x9464a2d0 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94c0ac50 1 1800 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94857650 1 1784 null dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94ad6ce0 1 1800 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x945e09a8 661 2994208 0x945e09f0 live org/apache/catalina/loader/StandardClassLoader@0x8cb28578

0x94ad56b0 1 1800 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94c0a898 1 1808 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x94851b50 4 9544 null dead javax/management/remote/rmi/NoCallStackClassLoader@0x8ca81c88

0x94ad33a0 1 1800 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x9464a2d0 800 3519760 0x945f97d0 live org/apache/catalina/loader/WebappClassLoader@0x8cee3928

0x94ad1a58 1 1800 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x945f97d0 0 0 0x945e09a8 live org/apache/catalina/loader/StandardClassLoader@0x8cb28578

0x945fda98 0 0 0x945e09f0 live java/util/ResourceBundle$RBClassLoader@0x8caedee8

0x94ad6ff0 1 1800 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

0x945e0a38 0 0 null live sun/misc/Launcher$ExtClassLoader@0x8c72c0a8

0x94c0ab00 1 1768 0x945e0960 dead sun/reflect/DelegatingClassLoader@0x8c6317a0

total = 60 4178 19203080 N/A alive=9, dead=51 N/A

If you need more information regarding the Jmap command then please click on next link : Jmap Commandin Linux.

Jstack Command

Jstack command used to trace Java process stack trace.

Usage of jstack as follows :

jstack <PID>

Its output is very bigger thats why I couldn't paste here. Please check your own to exact output as above format.

Click here to know more about: While Loop in Shell Scripting

And most important command for java process is that jinfo.

Jinfo Command

Jinfo command gives configuration information of java process.

Usage:

jinfo <PID>

jinfo <OPTIONS> <PID>

example of jinfo command as :

root@Hello:~# jinfo 9020

Attaching to process ID 9020, please wait...

Debugger attached successfully.

Server compiler detected.

JVM version is 20.0-b12

Java System Properties:

java.runtime.name = OpenJDK Runtime Environment

sun.boot.library.path = /usr/lib/jvm/java-5-openjdk/jre/lib/i586

java.vm.version = 20.0-b12

shared.loader = ${catalina.base}/shared/classes,${catalina.base}/shared/lib/*.jar

java.vm.vendor = Sun Microsystems Inc.

java.vendor.url = http://java.sun.com/

java.rmi.server.randomIDs = true

path.separator = :

tomcat.util.buf.StringCache.byte.enabled = true

java.util.logging.config.file = /hello/test/tomcat/conf/logging.properties

java.vm.name = OpenJDK Server VM

file.encoding.pkg = sun.io

sun.java.launcher = SUN_STANDARD

user.country = IN

sun.os.patch.level = unknown

com.sun.management.jmxremote.port = 3080

java.vm.specification.name = Java Virtual Machine Specification

user.dir = /hello/test/tomcat/bin

java.runtime.version = 1.6.0_24-b24

java.awt.graphicsenv = sun.awt.X11GraphicsEnvironment

java.endorsed.dirs = /hello/test/tomcat/common/endorsed

os.arch = i386

java.io.tmpdir = /hello/test/tomcat/temp

line.separator =

java.vm.specification.vendor = Sun Microsystems Inc.

java.naming.factory.url.pkgs = org.apache.naming

java.util.logging.manager = org.apache.juli.ClassLoaderLogManager

os.name = Linux

sun.jnu.encoding = UTF-8

java.library.path = /usr/lib/jvm/java-5-openjdk/jre/lib/i586/server:/usr/lib/jvm/java-5-openjdk/jre/lib/i586:/usr/lib/jvm/java-6-openjdk/jre/../lib/i386:/usr/java/packages/lib/i386:/usr/lib/jni:/lib:/usr/lib

java.specification.name = Java Platform API Specification

java.class.version = 50.0

sun.management.compiler = HotSpot Tiered Compilers

os.version = 3.0.0-12-generic

com.sun.management.config.file = /hello/test/tomcat/conf/management.properties

user.home = /root

catalina.useNaming = true

user.timezone = Asia/Kolkata

java.awt.printerjob = sun.print.PSPrinterJob

file.encoding = UTF-8

java.specification.version = 1.6

catalina.home = /hello/test/tomcat

java.class.path = :/hello/test/tomcat/bin/bootstrap.jar:/hello/test/tomcat/bin/commons-logging-api.jar

user.name = root

java.naming.factory.initial = org.apache.naming.java.javaURLContextFactory

package.definition = sun.,java.,org.apache.catalina.,org.apache.coyote.,org.apache.tomcat.,org.apache.jasper.

java.vm.specification.version = 1.0

org.xmldb.common.xml.queries.XPathQueryFactory = org.xmldb.common.xml.queries.xalan2.XPathQueryFactoryImpl

sun.java.command = org.apache.catalina.startup.Bootstrap start

java.home = /usr/lib/jvm/java-6-openjdk/jre

sun.arch.data.model = 32

user.language = en

java.specification.vendor = Sun Microsystems Inc.

java.vm.info = mixed mode

java.version = 1.6.0_24

java.ext.dirs = /usr/lib/jvm/java-6-openjdk/jre/lib/ext:/usr/java/packages/lib/ext

sun.boot.class.path = /hello/test/tomcat/common/endorsed/commons-collections-3.1.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/resources.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/rt.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/sunrsasign.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/jsse.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/jce.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/charsets.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/netx.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/plugin.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/rhino.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/modules/jdk.boot.jar:/usr/lib/jvm/java-6-openjdk/jre/classes

server.loader = ${catalina.home}/server/classes,${catalina.home}/server/lib/*.jar

java.vendor = Sun Microsystems Inc.

catalina.base = /hello/test/tomcat

java.security.auth.login.config = ../conf/jaas.conf

file.separator = /

java.vendor.url.bug = http://java.sun.com/cgi-bin/bugreport.cgi

common.loader = ${catalina.home}/common/classes,${catalina.home}/common/i18n/*.jar,${catalina.home}/common/endorsed/*.jar,${catalina.home}/common/lib/*.jar

sun.io.unicode.encoding = UnicodeLittle

sun.cpu.endian = little

package.access = sun.,org.apache.catalina.,org.apache.coyote.,org.apache.tomcat.,org.apache.jasper.,sun.beans.

sun.cpu.isalist =

VM Flags:

-Djava.security.auth.login.config=../conf/jaas.conf -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djava.util.logging.config.file=/hello/test/tomcat/conf/logging.properties -Dcom.sun.management.config.file=/hello/test/tomcat/conf/management.properties -Dcom.sun.management.jmxremote.port=3080 -Xms512m -Xmx512m -XX:NewRatio=3 -XX:+UseAdaptiveSizePolicy -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/internet/apps/cmt/outofmemory.hprof -Djava.endorsed.dirs=/hello/test/tomcat/common/endorsed -Dcatalina.base=/hello/test/tomcat -Dcatalina.home=/hello/test/tomcat -Djava.io.tmpdir=/hello/test/tomcat/temp

If you want to more information of this command and click on next link : Jinfo command inLinux.

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Shell script for Fibonacci Series

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It is very easy to learn bash shell scripting. There are different Unix shells like bash, ksh, zsh, sh etc. Please make sure that which shell do you want to use while running the script, because syntax of each shell might be different. Before going to develop shell script, your logic or flow of the script should be clear then only you can develop shell script very easily. It is very important to have clear understanding of when or where not to use shell script. 

 

For Fibonacci series shell script, need to know the exact number series. It will be as :

1              1              2              3              5              8              13           21            34          etc.

Please see below is the script to get desired output. 

######################Fibonacci.sh###############################

echo "How many numbers do you want of Fibonacci series ?"

  read total

  x=0

  y=1

  i=2

  echo "Fibonacci Series up to $total terms :: "

  echo "$x"

  echo "$y"

  while [ $i -lt $total ]

  do

      i=`expr $i + 1 `

      z=`expr $x + $y `

      echo "$z"

      x=$y

      y=$z

  done

Click to  know more about: Difference of Linux and Unix

#####################################################################

Now just save it as Fibonacci.sh and give the input as how many numbers you want of . Your output will be as follows: 

#####################################################################

root@hello:~/ctier/test/JBoss#

root@hello:~/ctier/test/JBoss# ./Fibnonacci.sh

How many numbers do you want of Fibonacci series ?

10

Fibonacci Series up to 10 terms ::

0

1

1

2

3

5

8

13

21

34

root@hello:~/ctier/test/JBoss#

#####################################################################

Before developing this script you should have clear understandings of while loop in shell script  and addition of numbers i.e. mathematical calculations in shell script.

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While Loop in Shell Scripting

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If you are already familiar with C or C++ coding then it is very easy to understand while loop in shell scripting. The Shell script while loop is same as other languages but different with syntax only. In bash shell scripting, while loop helps to run loop till the criteria fails. It is very useful when you want to run same command multiple times with change of some of the commands or its input.

The basic syntax of while loop in linux as follows:

while [ condition ]

do

                Our command 1;

                Command 2

                Command3

done

 Above while loop works as : if condition is satisfied then control comes inside the while loop and it will execute the command1, command then command3. And finally loop will exit.

While loop example in Linux:

root@hello:~/hello/test/test1# i=1;

root@hello:~/hello/test/test1#  while [ $i -lt 5 ]

> do

> echo $i;

> (( i++ ));

> done

1

2

3

4

root@hello:~/ctier/test/test1#

There are some changes in syntax of while loop as shell changes. In bash scripting, above syntax will work but in ksh it will not.

For KSH, you need to run the while as follows:

while [[ condition ]] ;

do

command 1 ;

command 2;

done

while loop with multiple conditions as follows:

while [ "$var1" != "$var2" || "$var1" == "$var3" || "$var2" != "$var4" ]

do

                commands here;

done

You can use counter inside the while loop as :

let counter=counter+1;

or

(( i++))

How to Run Unix Commands on Windows

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Cygwin is the best application which creates unix like environment in Windows OS. We can run almost all commands on Cygwin. Processing of files in windows will be easy if we use unix commands to process.

You can use openssh server in cygwin and create password less connection as well. There are many features of Cygwin that we will discuss in other article.

Please see below  for  brief information about installation of cygwin.

How to install cygwin ?

1.        It is very easy step. Go to this link Download Cygwin. 

2.       Download setup.exe only.

3.       Run the setup.exe and you can see first pop up as follows:

 

Click here to know more about: Jstat Command in Linux

4.       Select Install from Local directory, if you have already downloaded all packages otherwise select first option i.e. Install from Internet and click next.

 

5.       After that you will get next window where setup is asking for root directory if you have selected the Install from local directory. Otherwise give the path where you want to keep all cygwin related files and then click on next.

 

6.       Now it will ask for Internet settings if you have i.e. for proxy settings if you have. Otherwise select Direct Connection option.

 

7.       Now you will get mirror list. Select any mirror and click on next.

 

8.       It is the last step and most important step about Cygwin installation. Please be careful while selecting the packages which you need with cygwin. If you have not selected respective package then you will not get the commands of that package in your cygwin and you will get error message like "Command not found". If you are going to select all packages then Cygwin will take too much time to complete and you will install unnecessary packages as well.

 

After selection of packages, installation process will start. click on next and then finish. 

and then you will get the desktop icon for Cygwin Launch. Double click on this and Cygwin will start  and start to run unix commands on Windows

 

If you need any help regarding Cygwin then you can reach me on linuxconcepts@gmail.com.

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