Table of contents

Common JVM Command-Line Tools

Obtain the PID of a Java Process

jps -l

This returns the PID of the Java process, which you will use in the commands below.

Inspect the Options of the Current Java Process

1. View the options of the current JVM

   jinfo -flags pid

2. View the value of a specific option

   # View the initial heap size of the current Java process
   jinfo -flag InitialHeapSize pid

   # Check whether the current Java process uses the UseG1GC garbage collector
   jinfo -flag UseG1GC pid

3. Change JVM options dynamically: enable or disable Boolean options, or assign a value to an option

   # Enable GC logging; use +/- to enable or disable Boolean options
   jinfo -flag +PrintGCDetails
   
   # Set the thread stack size to 512k; use option=value for value-based options
   jinfo -flag ThreadStackSize=512k

4. View information about the current heap

   jmap -heap pid

Graphical Tools Included with the JDK

1. Common tools include jvisualvm and jconsole. I recommend jvisualvm. Enter the following directly in a terminal:

   jvisualvm

You can connect to a local or remote JVM.

You can see which options are in effect for the current JVM.