#JAVA 8 UPDATE 131 HOW TO#

Based on this setting, JVM is allocating Max heap size to be 494.9MB (approximately half of 1GB). Here you can see when docker containerвЂ™s memory is set to вЂ-m 1GBвЂ™ and вЂ-XX:MaxRAMPercentage=50вЂ™. # docker run -m 1GB openjdk:10 java -XX:MaxRAMPercentage=50 -XshowSettings:vm -version

1/2 of 1GB) will be allocated to your Java heap size. Say you have allocated 1 GB of memory to your container, then if you configure -XX:MaxRAMPercentage=50, then approximately 512MB (i.e. So, if you are running on older JDK versions, you canвЂ™t use this JVM argument. вЂ-XX:MaxRAMPercentageвЂ™, вЂ-XX: MinRAMPercentageвЂ™ JVM arguments are supported from Java 8 update 191 and above. XX:MaxRAMPercentage, -XX: MinRAMPercentage Supported Version It is only supported from Java 8 update 131 to Java 8 update 190. This argument has been deprecated in modern Java versions. Say suppose if your application requires 1GB heap size for optimal performance and if container is configured to run with memory size that is less than 1GB then your application will still run but it will suffer from poor performance characteristics.Д¬. In this option your Java applicationвЂ™s heap size will be derived from the containerвЂ™s memory size (because it is fraction basis). Improperly specified VM option 'MaxRAMFraction=2.5'Д®rror: Could not create the Java Virtual Machine.Д®rror: A fatal exception has occurred. # docker run -m 1GB openjdk:8u131 java -XX:+UnlockExperimentalVMOptions -XX:+UseCGroupMemoryLimitForHeap -XX:MaxRAMFraction=2.5 -XshowSettings:vm -version VM

See the below example where JVM is failing to start. It is because вЂ-XX:MaxRAMFractionвЂ™ can take only integer values and not decimal values. When you pass 2.5 as the value, JVM will not start. Say if you want to configure 40% of the dockerвЂ™s memory size, then we must set вЂ-XX:MaxRAMFraction=2.5вЂ™. To learn more about their difference read this article. This name makes us think, вЂ-XX:MinRAMFractionвЂ™ argument is used to configure minimum heap size. JDK development team could have given a better name than вЂ-XX:MinRAMFractionвЂ™. Note: Both вЂ-XX:MaxRAMFractionвЂ™ and вЂ-XX:MinRAMFractionвЂ™ are used to determine the maximum Java heap size. Based on this setting, JVM is allocating Max heap size to be 494.9MB (approximately half the size of 1GB). Here you can see when the docker containerвЂ™s memory is set to вЂ1GBвЂ™ (i.e., -m 1GB) and вЂ-XX:MaxRAMFraction=2. # docker run -m 1GB openjdk:8u131 java -XX:+UnlockExperimentalVMOptions -XX:+UseCGroupMemoryLimitForHeap -XX:MaxRAMFraction=2 -XshowSettings:vm -version VM settings: Only if you pass these two JVM arguments then JVM will derive the heap size value from the containerвЂ™s memory size, otherwise, it will derive the heap size value from the underlying hostвЂ™s memory size.

If you are going to use вЂ-XX:MaxRAMFractionвЂ™ JVM argument, make sure to pass these two additional JVM arguments as well вЂ-XX:+UnlockExperimentalVMOptions -XX:+UseCGroupMemoryLimitForHeapвЂ™. Say you have allocated 1 GB of memory to your container, then if you configure -XX:MaxRAMFraction=2, then approximately ~512MB (i.e. So, if you are using any other version of JDK, you cannot use this option. вЂ-XX:MaxRAMFractionвЂ™, вЂ-XX:MinRAMFractionвЂ™ JVM arguments are supported from only Java 8 update 131 to Java 8 update 190. XX:MaxRAMFraction, -XX:MinRAMFraction Supported Version Let us discuss these JVM arguments, their merits, and shortcomings. XX:MaxRAMPercentage, -XX:MinRAMPercentage There are 3 different options to specify the maximum Java heap size in containers.

#JAVA 8 UPDATE 131 HOW TO#

If you are porting your application to Containers, you might be wondering how to configure Java heap size in the containerвЂ™s world? Are there any best practices? In this article, we will discuss the possible JVM arguments that can be used to specify the Java heap size and the best option to choose. When you are running your Java application in physical servers, you would have been using вЂ-XmxвЂ™ JVM argument to specify the Java heap size.