Gradle Configuration Cache Issue With JreTask: How To Fix

Nov 25, 2025 by Alex Johnson 58 views

Introduction

Are you encountering issues with Gradle's configuration caching due to the org.beryx.runtime.JreTask? You're not alone! Many developers exploring Gradle's configuration caching feature have run into this snag. In this comprehensive guide, we'll delve into the problem, understand why it occurs, and explore potential solutions to get your Gradle builds running smoothly with configuration caching enabled. Gradle's configuration caching is a powerful feature designed to speed up build times by reusing the results of previous configurations. However, certain tasks, like org.beryx.runtime.JreTask, can prevent configuration caching from working effectively, leading to frustrating build failures.

Understanding the Problem

The core issue lies in the way org.beryx.runtime.JreTask interacts with Gradle's project object during execution. Gradle's configuration cache doesn't support accessing the project object at execution time. When a task attempts to do so, it violates the constraints of the configuration cache, resulting in an InvalidUserCodeException. Let's break down the error message to understand this better:

Invocation of `Task.project` at execution time is unsupported with the configuration cache.

- task `:jre` of type `org.beryx.runtime.JreTask`
    - Exception at `org.beryx.runtime.BaseTask.getDefaultJavaHome(BaseTask.groovy:55)`

This message indicates that the jre task, which is an instance of org.beryx.runtime.JreTask, is attempting to access the project object within the getDefaultJavaHome method. This access occurs at execution time, which is a no-go for configuration caching. The exception further points to the specific line of code causing the issue:

Exception at `org.beryx.runtime.BaseTask.getDefaultJavaHome(BaseTask.groovy:55)`
    org.gradle.api.InvalidUserCodeException: Invocation of 'Task.project' by task ':jre' at execution time is unsupported with the configuration cache.
    	at org.gradle.api.DefaultTask.getProject(DefaultTask.java:60)
    	at org.beryx.runtime.BaseTask.getDefaultJavaHome(BaseTask.groovy:55)

The stack trace provides a clear path to the root of the problem: the getDefaultJavaHome method in BaseTask.groovy is calling Task.project, which is prohibited during execution when configuration caching is enabled. To fully grasp the impact, it's crucial to understand why accessing the project object at execution time is problematic for Gradle's configuration cache. The configuration cache works by serializing the configuration phase of a build and reusing it in subsequent builds. This means that any task that relies on mutable project state during execution can break the cache's integrity. The project object is inherently mutable, as it represents the current state of the Gradle project. Accessing it at execution time can lead to unexpected behavior and invalidate the cache.

Reproducing the Issue

To reproduce this issue, you'll need a Gradle project that uses the org.beryx.runtime plugin and has configuration caching enabled. Here's how you can set up a minimal project to demonstrate the problem:

Enable the STABLE_CONFIGURATION_CACHE feature preview in your settings.gradle file:
```
enableFeaturePreview("STABLE_CONFIGURATION_CACHE")
```

Enable configuration caching in your gradle.properties file:

org.gradle.configuration-cache=true
org.gradle.configuration-cache.parallel=true

Define a task that depends on the jre task in your build.gradle file:

tasks.named("jre") {
    dependsOn downloadJRE, downloadJavaFXModules
}

With these settings in place, running a Gradle build will trigger the warning or exception related to the JreTask and its incompatibility with configuration caching. The user who reported the issue provided a real-world example using the PCGen project, highlighting that this problem can arise in complex, open-source projects as well. The simplicity of the provided Groovy code snippet underscores that the issue isn't necessarily tied to intricate build logic; rather, it stems from the fundamental interaction between the JreTask and Gradle's configuration caching mechanism. By following these steps, you can reliably reproduce the issue and gain a firsthand understanding of the challenges posed by org.beryx.runtime.JreTask in the context of Gradle's configuration cache.

Analyzing the Exception

Let's dissect the exception in detail to gain a deeper understanding of the problem. The exception message is quite informative:

org.gradle.api.InvalidUserCodeException: Invocation of 'Task.project' by task ':jre' at execution time is unsupported with the configuration cache.

This clearly states that the jre task is attempting to use Task.project during execution, which is incompatible with configuration caching. The stack trace provides further clues:

	at org.gradle.api.DefaultTask.getProject(DefaultTask.java:60)
    	at org.beryx.runtime.BaseTask.getDefaultJavaHome(BaseTask.groovy:55)
    	at org.beryx.runtime.JreTask_Decorated.getDefaultJavaHome(Unknown Source)
    	at org.beryx.runtime.BaseTask.getJavaHomeOrDefault(BaseTask.groovy:46)
    	at org.beryx.runtime.JreTask_Decorated.getJavaHomeOrDefault(Unknown Source)
    	at org.beryx.runtime.JreTask.getJavaHome(JreTask.groovy:48)
    	at org.beryx.runtime.JreTask_Decorated.getJavaHome(Unknown Source)

The stack trace reveals that the issue originates in the getDefaultJavaHome method of the BaseTask class within the org.beryx.runtime plugin. This method attempts to access the project object to determine the default Java home. The JreTask then calls this method to obtain the Java home for the JRE. The critical point here is that this access happens during task execution, which violates the configuration cache's constraints. To resolve this, we need to find a way to provide the Java home information without accessing the project object at execution time. This might involve alternative methods for determining the Java home or refactoring the task to avoid runtime access to the project state. Analyzing the exception and its stack trace is crucial for pinpointing the exact location of the problem and devising effective solutions. In this case, the exception clearly points to the getDefaultJavaHome method as the culprit, providing a starting point for further investigation and potential fixes.

Potential Solutions and Workarounds

Now that we understand the problem, let's explore some potential solutions and workarounds. Here are a few approaches you can consider:

Refactor the JreTask: The ideal solution would be to modify the org.beryx.runtime plugin to avoid accessing the project object at execution time. This might involve:
- Determining the Java home during the configuration phase instead of the execution phase.
- Using a different mechanism for obtaining the Java home, such as environment variables or Gradle properties.
- Caching the Java home value and reusing it across builds.
Provide Java Home as a Parameter: Instead of relying on the task to determine the Java home, you could provide it as a parameter. This could be a Gradle property or an environment variable. This approach would decouple the task from the project object and make it compatible with configuration caching.
Disable Configuration Caching for the JreTask: As a temporary workaround, you can disable configuration caching for the JreTask specifically. This can be done using Gradle's task configuration options. However, this approach will reduce the overall benefits of configuration caching, so it should be considered a last resort.
Use Gradle's Toolchains: Gradle's toolchains feature provides a more robust and recommended way to manage Java toolchains. By leveraging toolchains, you can specify the required Java version for your build, and Gradle will automatically provision it if necessary. This approach eliminates the need for the JreTask to determine the Java home at execution time.

Each of these solutions has its own trade-offs. Refactoring the JreTask is the most effective long-term solution, but it requires modifying the plugin's code. Providing the Java home as a parameter is a simpler workaround, but it might require changes to your build scripts. Disabling configuration caching for the JreTask should only be used as a temporary fix, as it negates the benefits of caching for that particular task. Using Gradle's toolchains is the most Gradle-idiomatic approach and is highly recommended for managing Java versions in your builds. The choice of solution will depend on your specific needs and the complexity of your project. It's important to carefully evaluate the options and choose the one that best fits your situation.

Implementing a Workaround

Let's walk through a practical workaround: providing the Java home as a parameter. This approach allows you to bypass the JreTask's need to access the project object at execution time. Here's how you can implement this:

Define a Gradle Property: Add a property to your gradle.properties file to specify the Java home:
```
java.home=/path/to/your/java/home
```
Replace /path/to/your/java/home with the actual path to your Java installation.
Modify the JreTask Configuration: In your build.gradle file, configure the JreTask to use the provided Java home property:
```
tasks.named("jre") {
    javaHome = file(project.properties['java.home'])
    dependsOn downloadJRE, downloadJavaFXModules
}
```
This code snippet retrieves the java.home property from the project's properties and sets it as the javaHome for the JreTask. By setting the javaHome property directly, we prevent the task from needing to determine it at execution time, thus resolving the configuration caching issue. This workaround is relatively simple to implement and doesn't require modifying the plugin's code. However, it does require you to explicitly specify the Java home in your gradle.properties file. While this might seem like a minor inconvenience, it ensures that the Java home is consistent across builds and environments, which can be beneficial in the long run. It's important to note that this is just one example of a workaround. Depending on your specific needs and project setup, you might need to adapt this approach or explore other solutions. The key takeaway is to understand the root cause of the problem and find a way to provide the necessary information to the task without violating the constraints of Gradle's configuration cache.

Conclusion

Encountering issues with Gradle's configuration caching and tasks like org.beryx.runtime.JreTask can be frustrating, but understanding the root cause is the first step toward resolving them. By avoiding accessing the project object at execution time, you can ensure compatibility with configuration caching and enjoy faster, more efficient builds. Remember, refactoring the task, providing Java home as a parameter, or using Gradle's toolchains are all viable solutions. If you're looking for more in-depth information about Gradle's configuration cache, be sure to check out the official Gradle documentation. Happy building!