Create the `JdwpRemoteDebugPlugin` and the `Debug errorprones` Intellij debug config, to make debugging error-prones easier by kelvinou01 · Pull Request #181 · palantir/suppressible-error-prone

kelvinou01 · 2025-10-03T13:43:13Z

Before this PR

In this repo, and every repo which consumes suppressible-error-prone, to debug errorprones, we have to

Create a Remote JVM Debug config following some instructions
Add the snippet below to the build-under-test
Run the debug config
Run the test

tasks.withType(JavaCompile).configureEach {
    it.options.forkOptions.jvmArgumentProviders.add(new CommandLineArgumentProvider() {
        @Override
        public Iterable<String> asArguments() {
            return List.of("-agentlib:jdwp=transport=dt_socket,server=n,address=localhost:5006")
        }
    })
}

After this PR

Simplify step 1 by creating a debug config file, which can also be replicated to other repositories like gradle-baseline

Also, simplify step 2 by exporting a gradle plugin which does the above for you.

==COMMIT_MSG==
Create the JdwpRemoteDebugPlugin and the Debug errorprones Intellij debug config, to make debugging error-prones easier
==COMMIT_MSG==

Possible downsides?

Removing step 1 would be a game changer. I tried to do this with a compound task which ran both the jdwp listener and the test build, but there was no way to run a compound task which runs a specific test case, like how intellij allows you to run test cases from the gutter.

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Create the JdwpRemoteDebugPlugin and the Debug errorprones Intellij debug config, to make debugging error-prones easier

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aldexis · 2025-10-03T14:01:38Z

@@ -0,0 +1,15 @@
+<component name="ProjectRunConfigurationManager">


Is this intentional? I've generally seen run configurations be added by leveraging the idea gradle plugin

yep! im using https://www.jetbrains.com/help/idea/run-debug-configuration.html#share-configurations

This is fine for having it in just this repo - however, the real dream for a plugin like this would be you can use it debug errorprone sources too (like gradle-baseline) and get this in the error-prone source repo too automatically. I think you'd need to make another plugin for this though that you apply in the errorprone source (that adds this run configuration). I don't think we currently have a plugin like that atm though.

Do you mean that we can add some code in RemoteDebugJavaCompilePlugin to create this configuration file in the repo we are running in, e.g. gradle-baseline, if it doesn't exist yet?

aldexis · 2025-10-03T14:03:23Z

+        project.getPluginManager().withPlugin("java", unused -> {
+            project.getTasks().withType(JavaCompile.class).configureEach(javaCompile -> {
+                javaCompile
+                        .getOptions()
+                        .getForkOptions()
+                        .getJvmArgumentProviders()
+                        .add(new CommandLineArgumentProvider() {
+                            @Override
+                            public Iterable<String> asArguments() {
+                                return List.of("-agentlib:jdwp=transport=dt_socket,server=n,address=localhost:5006");
+                            }
+                        });
+            });
+        });


Whenever I've debugged, I've wanted to debug a specific compilation task. If it requires to run another one it depends on, wouldn't this cause me to listen to the wrong one, since it's adding this to all the compilation tasks?

hmm, i thought you'd only be running one compilation task, no? whats an example where there are multiple compilations being done?

not necessarily. It'd be the case if you've set up the build-under-debug with multiple projects that compiling java, or a single project with multiple JavaCompile tasks, you can get this if you have different source sets that need compilation.

We expect the user to apply the debug plugin to the correct subproject, and hence configure the correct javacompile task. is this reasonable?

Not quite, because I might want to debug the test source set compilation, which typically depends on the main one. It should be enough in most cases though

if it is going to be used in other repos and not for the tests in suppressible errorprone, then it is confusing if you apply it in a repo that has more than one source set because you will have compileJava, compileTestJava, compileIntegrationTestJava, compile<SourceSet>Java. if you debug anything that's not the main source set, you may get into something weird.

My previous statement when you were devving on this was: it's fine to have a static file, but I assumed incorrectly on how it was supposed to be used. I think this would actually be perfect for having the dynamic pieces:
for each project that this is applied:

have a unique port for each compile task

generate a run configuration per project per compile task

so your menu would look like:

debug compile for gradle-suppressible-errorprone:compileJava

debug compile for gradle-suppressible-errorprone:compileTestJava

Not pushing for it in this PR, but it's a thought if you want this to be used widely

@CRogers has enlightened me that it's in listen mode and its completely fine to have multiple things listen on the same port! ignore me!

aldexis · 2025-10-03T14:04:25Z

+                    "The JDWP will throw a cryptic error when run with the configuration cache. Turn off configuration"
+                            + " cache for the build-under-debug. Hint: you can conditionally apply "
+                            + "`com.palantir.jdwp-remote-debug` only if `IntegrationTestKitBase#isJdwpLoaded()`");


I personally don't know off the top of my head how to disable the configuration cache. It might be good to provide instructions in here as to how to do this? (or even just forcefully disable it?)

It's only on if you run with --configuration-cache (e.g. using the methods in ConfigurationCacheSpec), and I don't think there's a way to disable it once your build is running :/ would be nice if we could!

--no-configuration-cache - but yes this should be in error message

felixdesouza · 2025-10-03T14:06:10Z

+ * To debug suppressible-error-prone in a build (works with breakpoints in VisitorStateModifications):
+ * 1. Run the "Debug errorprones" debug config which ships with this repository. Notably, it sets up a jdwp listener
+ *    at port 5006
+ * 2. Run the build with this plugin applied


be specific about what build you're referring to i.e. the build the under test

yep i should make all my terminologies very explicit. thanks for raising this.

felixdesouza · 2025-10-03T14:07:47Z

+ * 2. Run the build with this plugin applied
+ */
+public abstract class JdwpRemoteDebugPlugin implements Plugin<Project> {
+    // No other way to programmatically check whether the configuration-cache is on


not true!

Use BuildFeatures#getConfigurationCache

https://docs.gradle.org/current/javadoc/org/gradle/api/configuration/BuildFeatures.html

wow, thank you 🤯

felixdesouza · 2025-10-03T14:09:01Z

+        jdwpRemoteDebugPlugin {
+            id = 'com.palantir.jdwp-remote-debug'
+            displayName = 'JDWP Remote Debug Plugin'
+            description = 'Configures Java compilation tasks to connect to a remote JDWP debugger for debugging ErrorProne and other compiler processes.'
+            tags = ['jdwp', 'remote-debug', 'java', 'debugging', 'compiler']
+            implementationClass = 'com.palantir.gradle.suppressibleerrorprone.JdwpRemoteDebugPlugin'
+        }


is this something you want to publish? or you only want it for your tests. If the latter, we should not publish this here.

If the former, then it's probably a bit weird to publish within gradle-suppressible-error-prone

We want to publish this. @aldexis wants to use it in e.g baseline as well

if that's the case, then we should move it to gradle-utils, currently, you need to depend on gradle-suppressible-errorprone to get this, which is weird.

To be honest, I would even prefer for this to just be a configuration option in suppressible-error-prone that I can just turn on

hmm we only use this debugging plugin when we also have suppressible-error-prone, is it general enough to be put in gradle-utils?

I think the point is you can just slap this plugin on a repo using suppressible-error-prone without having to add another dependency to your buildscript - not really to be used as a generic compiler debug plugin used by other plugins.

okay, that makes a bit more sense. Let's add this to the README as well pls 🙏

felixdesouza · 2025-10-03T14:14:24Z

-                        }
-                    })
-                }
+                apply plugin: 'com.palantir.jdwp-remote-debug'


I like that you've encapsulated this in a plugin, pretty neat

CRogers · 2025-10-03T14:24:25Z

+        // To debug the tests in this file
+        // 1. Run the "Debug errorprones" debug configuration, which ships with this repository
+        // 2. Go to the test you're looking for and run debug on it as well, but without any special configurations
+        debug = isJwdpLoaded()


Pretty sure that nebula-test's IntegrationTestKitSpec already does this

yeah, but it sets it only when you're trying to create a runner, so your test code can't depend on it as it runs too late. It's kinda shit that they set it inside createRunner

Ah, you mean if you want to do something different depending on if debug is set.

It does, but only at runner creation time, which is too late unfortunately. we need it at setup time, when we create the build script

so we have to set it here early. i should explain this in a comment.

stale · 2025-10-18T04:44:47Z

This PR has been automatically marked as stale because it has not been touched in the last 14 days. If you'd like to keep it open, please leave a comment or add the 'long-lived' label, otherwise it'll be closed in 7 days.

Add plugin

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kelvinou01 added 2 commits October 3, 2025 14:46

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kelvinou01 added 6 commits October 3, 2025 15:32

i am a gradle noob

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even more docs

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stale Bot added the stale label Oct 18, 2025

kelvinou01 added long-lived autorelease merge when ready labels Oct 20, 2025

stale Bot removed the stale label Oct 20, 2025

		@@ -0,0 +1,15 @@
		<component name="ProjectRunConfigurationManager">

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kelvinou01 commented Oct 3, 2025 •

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changelog-app Bot commented Oct 3, 2025 •

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aldexis Oct 3, 2025 •

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