gnodet opened a new issue, #12445: URL: https://github.com/apache/maven/issues/12445
## Description Maven 4 hangs indefinitely during builds when the local repository is empty (e.g. `-Dmaven.repo.local=/fresh/path`). The build freezes at `maven-remote-resources-plugin:process` while resolving parent POMs of transitive dependencies. **The same build completes in seconds with a populated local repository.** ## Steps to Reproduce ```bash git clone --depth 1 https://github.com/apache/httpcomponents-stylecheck.git cd httpcomponents-stylecheck # Works fine (cached): mvn -B clean package -DskipTests # Hangs forever (empty repo): mvn -B clean package -DskipTests -Dmaven.repo.local=/tmp/fresh-repo ``` The build hangs at: ``` [INFO] --- remote-resources:3.0.0:process (process-resource-bundles) @ hc-stylecheck --- [INFO] Preparing remote bundle org.apache:apache-jar-resource-bundle:1.4 [INFO] Copying 3 resources from 1 bundle. ``` ## Thread Dump Analysis The **main thread** is stuck in `AbstractRequestCache.lambda$requests$0` (line 95) calling `Object.wait()` on a `HashMap` that it already holds the lock on: ``` "main" in Object.wait() java.lang.Thread.State: WAITING (on object monitor) at java.lang.Object.wait0(Native Method) - waiting on <0x000000070dadf9a8> (a java.util.HashMap) at org.apache.maven.impl.cache.AbstractRequestCache.lambda$requests$0(AbstractRequestCache.java:95) - locked <0x000000070dadf9a8> (a java.util.HashMap) at org.apache.maven.impl.cache.CachingSupplier.apply(CachingSupplier.java:50) at org.apache.maven.impl.cache.AbstractRequestCache.requests(AbstractRequestCache.java:144) at org.apache.maven.impl.AbstractSession.requests(AbstractSession.java:177) at org.apache.maven.impl.DefaultArtifactResolver.doResolve(DefaultArtifactResolver.java:106) at org.apache.maven.impl.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:65) at org.apache.maven.impl.AbstractSession.resolveArtifact(AbstractSession.java:689) at org.apache.maven.impl.resolver.DefaultModelResolver.getPath(DefaultModelResolver.java:181) at org.apache.maven.impl.resolver.DefaultModelResolver.doResolveModel(DefaultModelResolver.java:155) at org.apache.maven.impl.resolver.DefaultModelResolver.resolveModel(DefaultModelResolver.java:116) at org.apache.maven.impl.model.DefaultModelBuilder...resolveParent(DefaultModelBuilder.java:1101) ... at org.apache.maven.plugin.resources.remote.ProcessRemoteResourcesMojo.getProjects(ProcessRemoteResourcesMojo.java:665) ``` Meanwhile, **all 15 worker threads** (5× `BfDependencyCollector`, 5× `BasicRepositoryConnector`, 5× `resolver`) are idle in `LinkedBlockingQueue.take()`, waiting for work that is never submitted. ## Root Cause This appears to be a missed-signal deadlock in `AbstractRequestCache` / `CachingSupplier`: 1. The main thread enters `CachingSupplier.apply()` to resolve an artifact 2. Inside, it calls `Object.wait()` on a `HashMap`, expecting another thread to resolve the artifact and call `notify()` 3. But the resolution work is never dispatched to the worker threads — they sit idle in their thread pool queues 4. The main thread waits forever When the local repo is populated, the `CachingSupplier` returns the cached result immediately without entering the wait path. The deadlock only triggers when actual remote resolution is needed. ## Impact This affects any project using `maven-remote-resources-plugin` (very common — it's bound by default in the Apache parent POM) when built with a fresh local repository. This is the standard CI scenario where each build starts with an empty local repo. In the maven4-testing suite (testing ~966 Apache projects against Maven 4), this deadlock caused **21 of 57 failures** — all were 1-hour timeouts on projects that build fine on Maven 3 in under 6 minutes. ## Environment - Maven: 4.1.0-SNAPSHOT (commit 595458cd19) - Java: OpenJDK 25.0.3+9-LTS - OS: Linux - Plugin: maven-remote-resources-plugin 3.0.0 Full thread dump attached: all 27 threads, showing the main thread's full stack trace and all idle worker threads. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
