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You can also pin your JDK update version by using a value such as this: =1.8.0_202 Because the default is 1.8, you don’t need this file if you would like to use Java 8. Set a property in the file: =11Īccepted major version values are 1.7, 1.8, 11, 13, 15, and 17. You can specify a Java version by adding a file called system.properties to your application. We highly recommend running on a version of the JDK that is actively supported by the community. When a JDK version reaches EOL security patches may no longer be available. The JDK that your app uses will be included in the slug, which will affect your slug size. Depending on the major version you select the latest available update of that JDK will be used each time you deploy your app. OpenJDK versions 17, 15, 13, 11, and 7 are also available. Heroku currently uses OpenJDK 8 to run your application by default. See the troubleshooting article for more information about tuning a JVM process. The following flags are recommended for monitoring resource usage: -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+PrintTenuringDistribution -XX:+UseConcMarkSweepGC
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standard-2x: -Xm圆71m -XX:CICompilerCount=2.free, hobby or standard-1x: -Xmx300m -Xss512k -XX:CICompilerCount=2.When a new dyno type is selected, the following settings are automatically added to JAVA_TOOL_OPTIONS:
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-XX:+UseContainerSupport (for Java 11 and higher).When a Java process is started on your dyno, the following Java options will be added to JAVA_TOOL_OPTIONS and automatically picked up by Java: Individual options not overridden in the Procfile command or custom JAVA_TOOL_OPTIONS will still be in effect. Setting your own will cause its value to be appended to Heroku’s defaults and take precedence. You can also set your own JAVA_TOOL_OPTIONS config var. For example, to change the default of -Xmx300m, you could pass in: web: java -Xms150M -jar target/myapp.jar You can override these settings in the Procfile command (which takes precedence over the defaults). Since Java automatically picks it up, you do not need to include it in your Procfile command. Heroku uses this to set default Java options based on dyno size. JAVA_TOOL_OPTIONS is directly supported by Java and intended to augment a command line in environments where the command-line cannot be accessed or modified. JAVA_OPTS: Default Java options based on dyno size (identical to JAVA_TOOL_OPTIONS).JAVA_TOOL_OPTIONS: Default Java options based on dyno size.See Connecting to Relational Databases on Heroku with Java for more information. JDBC_DATABASE_URL: If a DATABASE_URL variable is present, this will be populated with the converted form.
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LD_LIBRARY_PATH: With the location of the JDK shared libraries.