Read the Garbage Collection (GC) configuration from external file in Java | Spring Boot

Question

Running a spring boot jar file with the given GC configuration

• -Xloggc:/file/path/gc.log
• -XX:+PrintGCTimeStamps
• -XX:+PrintGCDateStamps
• -XX:+PrintGCDetails

But, instead of passing all this GC information data in the command line when we are running the jar like

java -Dspring.profiles.active=<env-name> -Xmx5G -Xms2G -XX:MaxMetaspaceSize=2G -XX:+UseG1GC -Xloggc:/file/path/gc.log -XX:+PrintGCTimeStamps -XX:+PrintGCDateStamps -XX:+PrintGCDetails -jar application.jar

Is there any other approach that I can use to read the configuration from external file and pass it to jar

Edit :

As Slaw mentioned in the comment of using java Command-Line Argument Files

Created a file with args as name & the data it has is

-Dspring.profiles.active=<env-name> -Xmx5G -Xms2G -XX:MaxMetaspaceSize=2G -XX:+UseG1GC -Xloggc:/file/path/gc.log -XX:+PrintGCTimeStamps -XX:+PrintGCDateStamps -XX:+PrintGCDetails -jar application.jar

by running the jar like

java @args

getting error as

Error: Could not find or load main class @args

It was not able to find the Main class. I think it was not identifying the jar in the args file.

Answer 1

If you are using Java 9 and later, command line argument files (@file1) should work¹.

Another option for Java 9 and later is to set the JDK_JAVA_OPTIONS environment variable. This gives a list of options that will be automatically prepended to the java command line's JVM options.

For Java 8 and earlier, your options are more limited:

• Write a shell wrapper script, shell function or shell alias for either the java command or your application's command line.

• Explicitly add an environment variable when you use the java command; e.g.

     $ java $STD_OPTS my.app.Main args ...
  

• You could conceivably implement a custom launcher (in C) an have that do clever things such as emulating Java 9's @file mechanism.

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^{1 - Based on the symptoms, I think your attempt with @file failed either because the file was not found in the appropriate directory, or because you are using Java 8 or earlier.}