Java Command notes

JPS: View the process information in Java in this machine.

Jstack: Print thread stack information, make thread dump.

Jmap: Print memory map, make heap dump.

Jstat: Performance monitoring tool.

Jhat: Memory Analysis tool.

Jconsole: Easy Visualization Console.

JVISUALVM: A powerful console.

1.jps

2.jstack

http://www.hollischuang.com/archives/110

3.jmap

4.jstat (http://www.hollischuang.com/archives/481)

The Jstat is located in the Java Bin directory, which uses the JVM's built-in instructions to monitor the resources and performance of Java applications in real time, including the heap size and garbage collection status.

5.jhat (http://www.hollischuang.com/archives/1047)

The jhat command resolves the Java heap dump and launches a Web server, and then it can view the heap dump file in the browser.

6.jinfo (http://www.hollischuang.com/archives/1094)

Jinfo can output configuration information for Java processes, core files, or remote debug servers. These configuration information includes Java system parameters and command-line parameters, and if the process is running on a 64-bit virtual machine, you need to specify -J-d64 parameters such as:jinfo -J-d64 -sysprops pid

7.javap

JAVAP can see the bytecode generated by the Java compiler for us. It allows you to understand the internal work of many compilers against source code and bytecode.

-HelpHelp-LTable of output rows and variables-Public Output onlyPublicMethods and Fields-Protected Output onlyPublicAndProtectedClasses and Members-Package Output package only,PublicAndProtectedClass and member, which is the default-P-Private Output all classes and members-SOutput internal type signature-c < Span class= "pun" > output exploded code, for example, within each method of the class, including java - verbose  output stack size, number of method parameters -constants  Output static final constant 


                               usually  javap-c The  is more, which lists the JVM directives executed by each method, and shows the actual effect of the bytecode for each method. Through the comparison between bytecode and source code, we can deeply analyze the compiler principle of Java, and understand and solve various Java principle level problems. 



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Java Command notes