What are -Xms and -Xmx JVM parameters in java, And differences between them

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In this core java tutorial we will learn What are -Xms and -Xmx JVM parameters in java, And differences between -Xms and -Xmx JVM parameters in java.

Contents of page >

• 1) What is -Xms JVM parameter in java?
• Examples of using -Xms VM (JVM) option in java >
• 2) What is -Xmx JVM parameter in java?
• Examples of using -Xmx VM option in java >
• 3) What are differences between -Xms and -Xmx JVM parameters in java?

Before learning about -Xms and -Xmx JVM parameters in java we must know about java heap memory structure.

Earlier we read about JVM Heap memory (Hotspot heap structure)  in java consists of following elements>

1. Young Generation
• 1a) Eden,
• 1b) S0 (Survivor space 0)
• 1c) S1 (Survivor space 1)
2. Old Generation (Tenured)
3. Permanent Generation.

Read: How to write java program to pass VM parameters through CMD

Learn how to pass vmargs (VM parameters) to java program in eclipse?

1) What is -Xms JVM parameter in java?

-Xms : Xms is minimum heap size which is allocated at initialization of JVM in java.

Examples of using -Xms VM (JVM) option in java >

Example1 of using -Xms VM (JVM) option in java >

java -Xms512 MyJavaProgram

It will set the minimum heap size of JVM to 512 bytes.

Example2 of using -Xms VM (JVM) option in java >

java -Xms512k MyJavaProgram

It will set the minimum heap size of JVM to 512 kilobytes.

Example3 of using -Xms VM (JVM) option in java >

java -Xms512m MyJavaProgram

It will set the minimum heap size of JVM to 512 megabytes.

Example4 of using -Xms VM (JVM) option in java >

java -Xms1g MyJavaProgram

It will set the minimum heap size of JVM to 1 gigabyte.

2) What is -Xmx JVM parameter in java?

-Xmx : Xmx is the maximum heap size that JVM can use.

Examples of using -Xmx VM option in java >

Example1 of using -Xmx VM (JVM) option in java >

java -Xmx512 MyJavaProgram

It will set the maximum heap size of JVM to 512 bytes.

Example2 of using -Xmx VM (JVM) option in java >

java -Xmx512k MyJavaProgram

It will set the maximum heap size of JVM to 512 kilobytes.

Example3 of using -Xmx VM (JVM) option in java >

java -Xmx512m MyJavaProgram

It will set the maximum heap size of JVM to 512 megabytes.

Example4 of using -Xmx VM (JVM) option in java >

java -Xmx1g MyJavaProgram

It will set the maximum heap size of JVM to 1 gigabyte.

Read in detail about : OutOfMemoryError in java

3) What are differences between -Xms and -Xmx JVM parameters in java?

-Xms JVM parameter	-Xmx JVM parameter
Xms is minimum heap size which is allocated at initialization of JVM in java.	Xmx is the maximum heap size that JVM can use.
Examples of using -Xms VM (JVM) option in java > Example1 of using -Xms VM (JVM) option in java > java -Xms512m MyJavaProgram It will set the minimum heap size of JVM to 512 megabytes. Example2 of using -Xms VM (JVM) option in java > java -Xms1g MyJavaProgram It will set the minimum heap size of JVM to 1 gigabyte.	Examples of using -Xmx VM option in java > Example1 of using -Xmx VM (JVM) option in java > java -Xmx512m MyJavaProgram It will set the maximum heap size of JVM to 512 megabytes. Example2 of using -Xmx VM (JVM) option in java > java -Xmx1g MyJavaProgram It will set the maximum heap size of JVM to 1 gigabyte.

Summary -

So in this core java tutorial we learned what are -Xms and -Xmx JVM parameters in java, And differences between -Xms and -Xmx JVM parameters in java.

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RELATED LINKS>

>JVM (java virtual machine) in detail in java

>How Garbage Collection (GC) works internally in detail in java - BEST EXPLANATION EVER

 

Different type of garbage collectors in java>

>Serial collector / Serial GC (Garbage collector) in java

>Throughput GC (Garbage collector) or Parallel collector in java

>Concurrent Mark Sweep (CMS) collector / concurrent low pause garbage collector in java

>G1 garbage collector / Garbage first collector in java

Young, Old (tenured) and Permanent Generation >

>What are Young, Old (tenured) and Permanent Generation in JVM in java

Minor, Major and Full garbage collection >

>What are Minor, Major and Full garbage collection in JVM in java

Important VM parameters >

>Most important and frequently used VM (JVM) PARAMETERS with examples in JVM Heap memory in java

>-Xmn JVM parameters in java with examples - Setting young generation size

>What is -XX:NewRatio JVM parameters in java with examples - Setting young and old generation ratio

>What are -XX:NewSize and -XX:MaxNewSize JVM parameters in java

>-XX:SurvivorRatio JVM parameters in java with examples - Setting survivor spaces size

>-XX:+AggressiveHeap VM parameters

>What are -XX:PermSize and -XX:MaxPermSize JVM parameters with examples in java | Differences

>Solve java.lang.OutOfMemoryError : unable to create new native Thread - Xss JVM option

More VM parameters >

>How to use -verbose:gc VM argument

>-Xverify option in java

Labels: Core Java Garbage collection in java JVM JVM parameters VM/JVM options