How can I debug Gradle Worker Daemons in IntelliJ? - debugging

Question

I am using Gradle Worker Daemons in a custom task to enable parallel work.
The Worker API can accommodate this using the processIsolation() method that causes the work to execute in a separate "worker daemon". These worker daemon processes will persist across builds and can be reused during subsequent builds. If system resources get low, however, Gradle will stop any unused worker daemons.
Note that this not the same as the Gradle Daemon.
I am using Gradle 7.5.1 and IntelliJ IDEA 2022.3.2 (Ultimate Edition).
Basic example - GenerateMD5 WorkAction
I have recreated the basic example in the Worker Daemon docs that will generate MD5 files, based on the example in the Gradle docs.
The exception is that I am using an external library, Apache Commons Codec, to generate the MD5.
// build.gradle.kts
import org.apache.commons.codec.digest.DigestUtils
buildscript {
repositories {
gradlePluginPortal()
mavenCentral()
}
dependencies {
classpath("commons-codec:commons-codec:1.15")
}
}
plugins {
`java-library`
}
repositories {
gradlePluginPortal()
mavenCentral()
}
abstract class GenerateMD5 : WorkAction<GenerateMD5.Parameters> {
interface Parameters : WorkParameters {
val sourceFile: RegularFileProperty
val md5File: RegularFileProperty
}
override fun execute() {
val sourceFile = parameters.sourceFile.asFile.get()
val md5File = parameters.md5File.asFile.get()
val md5Hex = DigestUtils.md5Hex(sourceFile.inputStream())
println("Generated MD5 for ${sourceFile.name}: $md5Hex")
md5File.writeText(md5Hex)
}
}
dependencies {
implementation("commons-codec:commons-codec:1.15")
}
abstract class CreateMD5 : DefaultTask() {
#get:InputFiles
abstract val source: ConfigurableFileCollection
#get:Classpath
abstract val codecClasspath: ConfigurableFileCollection
#get:OutputDirectory
abstract val destinationDirectory: DirectoryProperty
#get:Inject
protected abstract val workerExecutor: WorkerExecutor
#TaskAction
fun createHashes() {
val workQueue: WorkQueue = workerExecutor.processIsolation {
classpath.from(codecClasspath)
forkOptions {
maxHeapSize = "64m"
//debug = true
}
}
source.files.forEach { file ->
workQueue.submit(GenerateMD5::class) {
sourceFile.set(file)
md5File.set(destinationDirectory.file("${file.name}.md5"))
}
}
}
}
val createMd5 by tasks.registering(CreateMD5::class) {
group = "md5"
codecClasspath.from(configurations.runtimeClasspath)
destinationDirectory.set(temporaryDir)
source.from(
resources.text.fromString(
"""
blah
blah
some
file
""".trimIndent()
)
)
}
Running without debug
When I run ./gradlew createMd5, the task executes successfully.
Executing 'createMd5'...
> Task :createMd5
Generated MD5 for string12197505505076104021.txt: 7a55d3ab41f37979cd7cccc92b7fc8fa
BUILD SUCCESSFUL in 866ms
1 actionable task: 1 executed
Execution finished 'createMd5'.
Running with debug
I then try and enable debug mode:
#TaskAction
fun createHashes() {
val workQueue: WorkQueue = workerExecutor.processIsolation {
classpath.from(codecClasspath)
forkOptions {
maxHeapSize = "64m"
debug = true // enable debug
}
}
// ...
I put a breakpoint in DigestUtils.java
And I then run the task with the debug options enabled in Intellij
However, I get an error.
Executing 'createMd5'...
Starting Gradle Daemon...
Connected to the target VM, address: '127.0.0.1:59032', transport: 'socket'
Gradle Daemon started in 1 s 460 ms
ERROR: transport error 202: bind failed: Address already in use
ERROR: JDWP Transport dt_socket failed to initialize, TRANSPORT_INIT(510)
JDWP exit error AGENT_ERROR_TRANSPORT_INIT(197): No transports initialized [./src/jdk.jdwp.agent/share/native/libjdwp/debugInit.c:735]
Could not write standard input to Gradle Worker Daemon 1.
java.io.IOException: Broken pipe
at java.base/java.io.FileOutputStream.writeBytes(Native Method)
at java.base/java.io.FileOutputStream.write(FileOutputStream.java:354)
at java.base/java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:81)
at java.base/java.io.BufferedOutputStream.flush(BufferedOutputStream.java:142)
at org.gradle.process.internal.streams.ExecOutputHandleRunner.forwardContent(ExecOutputHandleRunner.java:68)
at org.gradle.process.internal.streams.ExecOutputHandleRunner.run(ExecOutputHandleRunner.java:53)
at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:64)
at org.gradle.internal.concurrent.ManagedExecutorImpl$1.run(ManagedExecutorImpl.java:48)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.lang.Thread.run(Thread.java:829)
> Task :createMd5 FAILED
1 actionable task: 1 executed
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':createMd5'.
> A failure occurred while executing Build_gradle$GenerateMD5
> Failed to run Gradle Worker Daemon
> Process 'Gradle Worker Daemon 1' finished with non-zero exit value 2
* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.
* Get more help at https://help.gradle.org
BUILD FAILED in 6s
Disconnected from the target VM, address: '127.0.0.1:59032', transport: 'socket'
Execution finished 'createMd5'.
Attempts
I have tried killing the Gradle Daemon,
./gradlew --stop
but to no effect.
I have also tried killing the Gradle Daemon
pkill -f '.*GradleDaemon.*';
but this also did not work.

Answer 1

Please try attaching a remote debugger to the running gradlew command.
https://docs.gradle.org/current/userguide/troubleshooting.html#sec:troubleshooting_build_logic