A daemon is a computer program that runs as a background process rather than being under the direct control of an interactive user.
Gradle runs on the Java Virtual Machine (JVM) and uses several supporting libraries with non-trivial initialization time. Startups can be slow. The Gradle Daemon solves this problem.
The Gradle Daemon is a long-lived background process that reduces the time it takes to run a build.
The Gradle Daemon reduces build times by:
Caching project information across builds
Running in the background so every Gradle build doesn’t have to wait for JVM startup
Benefiting from continuous runtime optimization in the JVM
Watching the file system to calculate exactly what needs to be rebuilt before you run a build
The Gradle JVM client sends the Daemon build information such as command line arguments, project directories, and environment variables so that it can run the build. The Wrapper is responsible for resolving dependencies, executing build scripts, creating and running tasks; when it is done, it sends the client the output. Communication between the client and the Daemon happens via a local socket connection.
Daemons use the JVM’s default minimum heap size.
If the requested build environment does not specify a maximum heap size, the Daemon uses up to 512MB of heap. 512MB is adequate for most builds. Larger builds with hundreds of subprojects, configuration, and source code may benefit from a larger heap size.
To get a list of running Daemons and their statuses, use the
$ gradle --status
PID STATUS INFO 28486 IDLE 7.5 34247 BUSY 7.5
Currently, a given Gradle version can only connect to Daemons of the same version. This means the status output only shows Daemons spawned running the same version of Gradle as the current project.
If you have installed the Java Development Kit (JDK), you can view live daemons with the
33920 Jps 27171 GradleDaemon 22792
Live Daemons appear under the name
Because this command uses the JDK, you can view Daemons running any version of Gradle.
Gradle enables the Daemon by default since Gradle 3.0.
If your project doesn’t use the Daemon, you can enable it for a single build with the
--daemon flag when you run a build:
$ gradle <task> --daemon
This flag overrides any settings that disable the Daemon in your project or user
To enable the Daemon by default in older Gradle versions, add the following setting to the
gradle.properties file in the project root or your Gradle User Home (
You can disable the Daemon in multiple ways but there are important considerations:
- Single-use Daemon
If the JVM args of the client process don’t match what the build requires, a single-used Daemon (disposable JVM) is created. This means the Daemon is required for the build, so it is created, used, and then stopped at the end of the build.
- No Daemon
org.gradle.jvmargs, the Daemon will not be used at all since the build happens in the client JVM.
To disable the Daemon for a single build, pass the
--no-daemon flag when you run a build:
$ gradle <task> --no-daemon
This flag overrides any settings that enable the Daemon in your project including the
To disable the Daemon for all builds of a project, add
org.gradle.daemon=false to the
gradle.properties file in the project root.
On Windows, this command disables the Daemon for the current user:
(if not exist "%USERPROFILE%/.gradle" mkdir "%USERPROFILE%/.gradle") && (echo. >> "%USERPROFILE%/.gradle/gradle.properties" && echo org.gradle.daemon=false >> "%USERPROFILE%/.gradle/gradle.properties")
On UNIX-like operating systems, the following Bash shell command disables the Daemon for the current user:
mkdir -p ~/.gradle && echo "org.gradle.daemon=false" >> ~/.gradle/gradle.properties
There are two recommended ways to disable the Daemon globally across an environment:
add the flag
Don’t forget to make sure your JVM arguments and
JAVA_OPTS match if you want to completely disable the Daemon and not simply invoke a single-use one.
It can be helpful to stop the Daemon when troubleshooting or debugging a failure.
Daemons automatically stop given any of the following conditions:
Available system memory is low
Daemon has been idle for 3 hours
To stop running Daemon processes, use the following command:
$ gradle --stop
This terminates all Daemon processes started with the same version of Gradle used to execute the command.
You can also kill Daemons manually with your operating system. To find the PIDs for all Daemons regardless of Gradle version, see Find Daemons.
The Gradle Tooling API used by IDEs and other tools to integrate with Gradle always uses the Gradle Daemon to execute builds. If you execute Gradle builds from within your IDE, you already use the Gradle Daemon. There is no need to enable it for your environment.
We recommend using the Daemon for developer machines and Continuous Integration (CI) servers.
Gradle starts a new Daemon if no idle or compatible Daemons exist.
The following values determine compatibility:
Requested build environment, including the following:
Compatibility is based on exact matches of these values. For example:
If a Daemon is available with a Java 8 runtime, but the requested build environment calls for Java 10, then the Daemon is not compatible.
If a Daemon is available running Gradle 7.0, but the current build uses Gradle 7.4, then the Daemon is not compatible.
Certain properties of a Java runtime are immutable: they cannot be changed once the JVM has started. The following JVM system properties are immutable:
The following JVM attributes controlled by startup arguments are also immutable:
The maximum heap size (the
The minimum heap size (the
The boot classpath (the
The "assertion" status (the
If the requested build environment requirements for any of these properties and attributes differ from the Daemon’s JVM requirements, the Daemon is not compatible.
For more information about build environments, see the build environment documentation.
The Daemon can reduce build times by 15-75% when you build the same project repeatedly.
To understand the Daemon’s impact on your builds, you can profile your build with
In between builds, the Daemon waits idly for the next build. As a result, your machine only loads Gradle into memory once for multiple builds instead of once per build. This is a significant performance optimization.
The JVM gains significant performance from runtime code optimization: optimizations applied to code while it runs.
JVM implementations like OpenJDK’s Hotspot progressively optimize code during execution. Consequently, subsequent builds can be faster purely due to this optimization process.
With the Daemon, perceived build times can drop dramatically between a project’s 1st and 10th builds.
The Daemon enables in-memory caching across builds. This includes classes for plugins and build scripts.
Similarly, the Daemon maintains in-memory caches of build data, such as the hashes of task inputs and outputs for incremental builds.
Gradle actively monitors heap usage to detect memory leaks in the Daemon.
When a memory leak exhausts available heap space, the Daemon:
Finishes the currently running build.
Restarts before running the next build.
Gradle enables this monitoring by default.
To disable this monitoring, set the
org.gradle.daemon.performance.enable-monitoring Daemon option to
You can do this on the command line with the following command:
$ gradle <task> -Dorg.gradle.daemon.performance.enable-monitoring=false
Or you can configure the property in the
gradle.properties file in the project root or your GRADLE_USER_HOME (Gradle User Home):