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Build Server Reference

The build server is at the core of bloop. It runs in the background and is the responsible for scheduling and running client actions.

Bloop's build server is a long-running process designed to provide the fastest compilation possible to users. As such, users are responsible for managing its lifecycle and minimizing the amount of times it's restarted.

Start the build server

At the end of the day, the build server is an artifact in Maven Central. However, the recommended way of starting the server is via the bloop start invocation.

bloop start is an OS-independent way of starting the server that abstracts over some of the messy details of running a JVM application with the right configuration. For example, bloop start:

  1. Finds a JDK to use on your system or downloads a JDK if it's not available.
  2. Runs the server with the JVM options configured via BLOOP_JAVA_OPTS environment variable or bloop.java-opts property, see custom Java options.
  3. Makes sure that the server is running it connects to that specific server.
If you are integrating your tool with bloop and want to install and start the server automatically in the background, you can use Bloop's built-in bloop rifle.

bloop start

Usage

Usage: bloop start [options]
Starts a Bloop instance, if none is running

Help options:
  --usage            Print usage and exit
  -h, -help, --help  Print help message and exit

Other options:
  -v, --verbose                     Increase verbosity (can be specified multiple times)
  -q, --quiet                       Decrease verbosity
  --progress                        Use progress bars
  --home, --home-directory string?
  --java-home path                  Set the Java home directory
  -j, --jvm jvm-name                Use a specific JVM, such as `14`, `adopt:11`, or `graalvm:21`, or `system`
  -f, --force

Custom Java options

By default, Bloop server when run via the native launcher is configured to use:

  "-Xss4m",
  "-XX:MaxInlineLevel=20", // Specific option for faster C2, ignored by GraalVM
  "-XX:+UseZGC", // ZGC returns unused memory back to the OS, so Bloop does not occupy so much memory if unused
  "-XX:ZUncommitDelay=30",
  "-XX:ZCollectionInterval=5",
  "-XX:+IgnoreUnrecognizedVMOptions", // Do not fail if an non-standard (-X, -XX) VM option is not recognized.
  "-Dbloop.ignore-sig-int=true"

Update the BLOOP_JAVA_OPTS env variable or bloop.java-opts property to configure custom Java options that should be used when starting a new Bloop server. For example, use this to increase the memory to Bloop.

export BLOOP_JAVA_OPTS="-Xmx16G -XX:+UseZGC -Xss4m"

Custom Java home

By default Bloop CLI will try to find JDK 17 and up on your system, if it's not possible it will download a JDK 17 from the internet. If you want to use a different JDK, please make sure that JAVA_HOME is set correctly or use --java-home option.

bloop start --java-home "/Library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk"

The java binary should exist in $JAVA_HOME/bin/java. The Bloop server will not start correctly if the javaHome field points directly to the java binary.

Automatic management of the server

Depending on your operating system, there exist several solutions that allow you to start, stop, restart and inspect the status of the build server at any time.

Both the Bloop CLI and the Bloop Rifle, the tool used by build clients to connect to Bloop via BSP, will start the server if it's not running and connect to it.

You can exit the server by running bloop exit from the CLI. You can also kill it with kill, the Activity Monitor in your machine or htop.

Ignore exceptions in server logs

Bloop uses Nailgun, which sometimes prints exceptions in your server logs such as:

Unable to load nailgun-version.properties.
NGServer [UNKNOWN] started on address localhost/127.0.0.1 port 8212.
[W] Internal error in session
java.io.EOFException
    at java.base/java.io.DataInputStream.readInt(DataInputStream.java:397)
    at com.martiansoftware.nailgun.NGCommunicator.readCommandContext(NGCommunicator.java:140)
    at com.martiansoftware.nailgun.NGSession.run(NGSession.java:197)

You can safely ignore these warnings and exceptions.

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