Getting started with OpenJDK development

The aim of this tutorial is to help you setup your working environment for editing, building, and testing OpenJDK.

  sudo dnf install java-11-openjdk-devel

In order to test your changes in OpenJDK you will also need jtreg, installed as the path to jtreg needs to be provided to the configure script we will set it up before OpenJDK itself.

1. Clone jtreg:

     git clone https://github.com/openjdk/jtreg.git

2. Enter the directory and build it:

     cd jtreg
     bash make/build.sh --jdk path/to/existing/jdk

   This will create the directory build/images/jtreg which is the jtreg home.

3. (Optional but recommended) Install the jtreg plugin for IntelliJ IDEA

   The jtreg repo also contains a plugin for the IntelliJ IDE. This is a convenience plugin which adds jtreg capabilities to the IntelliJ IDE. With this plugin, OpenJDK developers can write, run, and debug jtreg tests without leaving their IDE environment. For more details, see the file plugins/idea/README.md in this repo.

1. Clone

     git clone https://github.com/openjdk/jdk.git

2. Enter the directory and run configure:

     cd jdk
     bash configure --with-boot-jdk=path/to/existing/jdk --with-jtreg=path/to/jtreg/build/images/jtreg

   Make sure to consult doc/building.md for more info and options.

3. Build OpenJDK:

     make images

   Congratulations, you should now have your own build of OpenJDK under build/linux-x86_64-server-release/images/jdk. Note, that path might be different depending on your system and configuration.

4. Start hacking… and recompile with make images

Now that we are all set up and know how to build and hack OpenJDK we should also make sure we don't break things :)

To run jtreg use:

make run-test TEST="hotspot/jtreg"

You can confine the range of the tests to the ones related to your changes by choosing specific sub-directories, e.g.:

make run-test TEST="hotspot/jtreg/compiler/jvmci"

You can also increase the verbosity of jtreg by setting VERBOSE inside the JTREG environment variable, e.g.:

make run-test JTREG="VERBOSE=all" TEST="hotspot/jtreg/compiler/jvmci"

For the list of available options one may run:

jterg -help "Verbose Options"

which will output something like the following:

Verbose Options
                These options control the amount of output written to the
                console while running tests

    -v | --v:<value> | -verbose | --verbose:<value>
                    Increase the amount of output written to the console. A
                    value, or selected combinations of values separated by
                    commas, may be given to select the type of output desired.
        default         Three lines of output per test: start, end, status
        summary         One line of output per test: status, test name
        all             Selected contents of JTR file for all tests (includes
                        stdout/stderr)
        pass            Selected contents of JTR file for passed tests
        fail            Selected contents of JTR file for failed tests
        error           Selected contents of JTR file for errored tests
        nopass          Suppress output for tests that passed
        time            Elapsed time per action
        multirun        Updates for each testsuite when tests from more than one
                        are being executed.
    -v1             Short for -verbose:summary
    -va             Short for -verbose:all
    -ve             Short for -verbose:error
    -vf             Short for -verbose:fail
    -vp             Short for -verbose:pass
    -vt             Short for -verbose:time

For the complete list of jtreg options please refer to https://openjdk.java.net/jtreg/command-help.html.

For more info about testing OpenJDK please refer to doc/testing.md