Red Hat
docs.redhat.com › en › documentation › red_hat_build_of_openjdk › 21 › html › configuring_red_hat_build_of_openjdk_21_on_rhel › configuring-heap-size-for-openjdk-application-on-rhel
Chapter 6. Configuring the heap size for Red Hat build of OpenJDK application on RHEL | Configuring Red Hat build of OpenJDK 21 on RHEL | Red Hat build of OpenJDK | 21 | Red Hat Documentation
November 18, 2024 - You can configure Red Hat build of OpenJDK to use a customized heap size. ... Add the maximum heap size option to the java command when running your application. For example, to set the maximum heap size to 100 megabytes, use the -Xmx100m option:
Azul
docs.azul.com › prime › Heap-Size
Recommended Heap Size
The -Xmx or -XX:MaxRAMPercentage command line parameters specifies the maximum Java heap size. That’s the amount of memory available for the Java application running on Azul Zing Builds of OpenJDK (Zing) to store its objects and classes.
Solved - Java Specify Heap Size OpenJDK11 | The FreeBSD Forums
I'm attempting to run a simple ... com.company.Main Invalid maximum heap size: -Xmx1024m:. Error: Could not create the Java Virtual Machine. Error: A fatal exception has occurred. Program will exit. $ java -version openjdk version "11.0.10" 2021-01-19 OpenJDK Runtime ... More on forums.freebsd.org
Increase heap size in Java - Stack Overflow
I am working on a Windows 2003 server (64-bit) with 8 GB RAM. How can I increase the heap memory maximum? I am using the -Xmx1500m flag to increase the heap size to 1500 Mb. Can I increase the heap More on stackoverflow.com
bash - How do I set the default maximum Java heap size? - Raspberry Pi Stack Exchange
I want to set the default Java heap size to 1024m without needing to specify the -Xmx option every time I run a jar file. Tried adding export JAVA_OPTIONS=-Xmx1024m to .bashrc file but it didn't work. ... I have not used Java for a while but I think it is _JAVA_OPTIONS as described in this answer stackoverflow.com/a/17613621/799759 ... _JAVA_OPTIONS is non-standard. However, at least some versions of openJDK ... More on raspberrypi.stackexchange.com
Java process consuming more memory than assigned Max heap
Java using more memory than Xmx is totally normal. You can at least calculate 1MB for each thread and 1MB for each TCP connection. If you run Java in Containers, we usually calculate Xmx * 1.5 for the container. This is a good video explaining it: https://www.youtube.com/watch?v=uJLOlCuOR4k If you have the impression of java processes eating even more than that, look into reusing TCP connections with pools, not leaking connections, etc. More on reddit.com
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February 28, 2024Red Hat
developers.redhat.com › articles › 2023 › 03 › 07 › overhauling-memory-tuning-openjdk-containers-updates
Overhauling memory tuning in OpenJDK containers updates | Red Hat Developer
September 19, 2023 - For these reasons, OpenJDK set the max heap default to 25% of available memory (whether that's total physical or container limited). We believe this is very low for the container use case, leaving 3/4 of container allocated memory unusable.
OpenJDK
openjdk.org › jeps › 8359211
JEP draft: Automatic Heap Sizing for G1
Setting up such an environment alone is challenging for most users. We argue that the JVM can automatically control the maximum Java heap size and balance CPU and memory consumption better than the user can manually with explicit configuration. The JVM should monitor the free memory available in the environment, and use that always current information to automatically determine a maximum heap size.
OpenJDK
openjdk.org › jeps › 8329758
JEP draft: Faster Startup and Warmup with ZGC
April 5, 2024 - The application starts quickly because the initial heap size is small, minimizing overhead, but pays a warmup cost because all other memory used for the heap -- up to 2GB -- is only obtained on-demand. Bad startup, good warmup. For example, java -Xms2G -Xmx2G –XX:+AlwaysPreTouch ... sets ...
OpenJDK
openjdk.org › jeps › 141
JEP 141: Increase the Client VM's Default Heap Size
Increase the default maximum heap size of the client JVM so that most client applications can run without tuning. Run a set of benchmarks provided by the client team without tuning and without running out of memory.
FreeBSD
forums.freebsd.org › development › userland programming and scripting
Solved - Java Specify Heap Size OpenJDK11 | The FreeBSD Forums
March 1, 2021 - I'm attempting to run a simple Java application with a specified max heap size (the system has more than 60GB free): $ /usr/local/bin/java -Xmx1024m:. com.company.Main Invalid maximum heap size: -Xmx1024m:. Error: Could not create the Java Virtual Machine. Error: A fatal exception has occurred. Program will exit. $ java -version openjdk version "11.0.10" 2021-01-19 OpenJDK Runtime Environment (build 11.0.10+9-1) OpenJDK 64-Bit Server VM (build 11.0.10+9-1, mixed mode) Am I missing something in order to specify the JVM size?
Top answer 1 of 14
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You can increase to 2GB on a 32 bit system. If you're on a 64 bit system you can go higher. No need to worry if you've chosen incorrectly, if you ask for 5g on a 32 bit system java will complain about an invalid value and quit.
As others have posted, use the cmd-line flags - e.g.
java -Xmx6g myprogram
You can get a full list (or a nearly full list, anyway) by typing java -X.
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It is possible to increase heap size allocated by the JVM by using these command line options:
-Xms<size> set initial Java heap size
-Xmx<size> set maximum Java heap size
-Xss<size> set java thread stack size
In the following example, minimum heap size is set to 16mb, and the maximum to 64mb:
java -Xms16m -Xmx64m ClassName
Rlemaitre
rlemaitre.com › articles › til › default-heap-configuration-in-openjdk
Default Heap Configuration in OpenJDK |> Raphaël Lemaitre
June 22, 2025 - For client configurations, as described ... size is half of the physical memory up to a physical memory size of 192 megabytes (MB) and otherwise one fourth of the physical memory up to a physical memory size of 1 gigabyte (GB)....
OpenJDK
openjdk.org › jeps › 8204088
JEP draft: Dynamic Max Memory Limit
To dynamically limit how large the committed memory (i.e. the heap size) can grow, a new dynamically user-defined variable is introduced: CurrentMaxHeapSize. This variable (defined in bytes) limits how large the heap can be expanded. It can be set at launch time and changed at runtime.
Red Hat
docs.redhat.com › en › documentation › red_hat_build_of_openjdk › 11 › html › configuring_red_hat_build_of_openjdk_11_for_windows › openjdk11-windows-config-custom-heap
Chapter 3. Configuring Red Hat build of OpenJDK to run with customized heap size | Configuring Red Hat build of OpenJDK 11 for Windows | Red Hat build of OpenJDK | 11 | Red Hat Documentation
May 9, 2024 - Red Hat build of OpenJDK 11 for Microsoft Windows can be configured to use a customized heap size. ... Run the application by adding maximum heap size option to your java command line. For example to set the maximum heap size to 100 megabytes use the -Xmx100m option.
OpenJDK
openjdk.org › jeps › 8350152
JEP draft: Automatic Heap Sizing for the Serial Garbage Collector
February 15, 2025 - This policy will automatically find a heap size that minimizes GC interference by dynamically adapting to changing circumstances on the server. It selects heap sizes within the minimum and maximum size boundaries, which users can still set as usual with the -Xms and -Xmx command-line options.
Baeldung
baeldung.com › home › java › jvm › jvm parameters initialrampercentage, minrampercentage, and maxrampercentage
JVM Parameters InitialRAMPercentage, MinRAMPercentage, and MaxRAMPercentage | Baeldung
June 5, 2024 - Then, let’s use the parameter to set the maximum heap size for a JVM with a total memory of 100MB: $ docker run -m 100MB openjdk:8 java -XX:MinRAMPercentage=80.0 -XshowSettings:VM -version VM settings: Max.
Top answer 1 of 2
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The maximum heap size is not the maximum amount of memory the JVM will use, but the heap size is what Xmx actually sets.
Regarding settings, it seems there maybe issues with JAVA_OPTIONS, a more bulletproof method would be to add this to .bashrc:
alias java='java -Xms1024m'
Or, since environment variables are interpolated in an alias:
alias java='java $MY_JAVA_OPTS'
export MY_JAVA_OPTS="-Xms1024m"
This gives you some flexibility if you want to add or override $MY_JAVA_OPTS for some session:
MY_JAVA_OPTS="$MY_JAVA_OPTS -Xprof -Xdiag"
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Solved this by adding export _JAVA_OPTIONS=-Xmx1024m to /etc/profile file.
OpenJDK
mail.openjdk.org › pipermail › hotspot-gc-dev › 2011-August › 003090.html
Default max heap size
> I found function set_heap_size defined here > http://hg.openjdk.java.net/jdk6/jdk6/hotspot/file/dc40301aed45/src/share/vm/runtime/arguments.cpp > > If am not wrong, the calculation happens in the following lines > > if (FLAG_IS_DEFAULT(MaxHeapSize)) { > julong reasonable_max = phys_mem / MaxRAMFraction; > > if (phys_mem<= MaxHeapSize * MinRAMFraction) { > // Small physical memory, so use a minimum fraction of it for the heap > reasonable_max = phys_mem / MinRAMFraction; > } else { > // Not-small physical memory, so require a heap at least > // as large as MaxHeapSize > reasonable_max = MAX2(reasonable_max, (julong)MaxHeapSize); > } > > > MaxRAMFraction is 4, so reasonable_max is phys_mem / 4.
OpenJDK
mail.openjdk.org › pipermail › hotspot-dev › 2022-September › 064190.html
Container-aware heap sizing for OpenJDK
September 13, 2022 - - From our work on Adaptable Heap Sizing, it appears they can! Design: - We add two manageable flags in the JVM - Current maximum heap expansion size - Current target heap size - A separate thread runs alongside the JVM, querying: - Container memory usage/limits - GC CPU overhead metrics from the JVM.
javaspring
javaspring.net › blog › how-do-i-set-java-s-min-and-max-heap-size-through-environment-variables
How to Set Java Min and Max Heap Size via Environment Variables on Your Server — javaspring.net
The JVM adjusts heap size between -Xms and -Xmx based on usage. Fine-tune this with: -XX:MinHeapFreeRatio=40: Minimum percentage of heap free after GC (prevents shrinking too much).
Mkyong
mkyong.com › home › java › find out your java heap memory size
Find out your Java heap memory size - Mkyong.com
March 9, 2014 - $ java -XX:+PrintFlagsFinal -version ... allocated following default values : Java heap size InitialHeapSize = 64781184 bytes (61.7M) and MaxHeapSize = 1038090240 bytes (990M)....
Medium
medium.com › @marketing_864 › best-practices-java-memory-arguments-for-containers-1d704a65f7db
Best practices: Java memory arguments for Containers | by Ram Lakshmanan | Medium
December 17, 2020 - Say you have allocated 1 GB of memory to your container, then if you configure -XX:MaxRAMPercentage=50, then approximately 512GB (i.e. 1/2 of 1GB) will be allocated to your Java heap size.