fix(maven): synchronize batch runner invoke() to prevent concurrent access (#34600)

MaxKless · claude · web-flow · commit 53c0123beffb · 2026-02-27T08:30:37.000-05:00
## Current Behavior

The Maven batch runner uses a parallel thread pool to execute tasks.
When multiple tasks are independent roots in the task graph, they get
picked up by separate threads simultaneously. Both threads call
`invoke()` on the same shared `CachingResidentMavenInvoker` (Maven 4) or
`CachingMaven3Invoker` (Maven 3) instance concurrently.

Maven 4's `LookupInvoker.invoke()` is not thread-safe — it
snapshots/restores `System.getProperties()` and the thread context
classloader in a `finally` block, and all concurrent invocations share
the same resident `MavenContext`. This can cause deadlocks in Maven's
internal session machinery.

## Expected Behavior

Maven executions through the shared invoker are serialized via
`@Synchronized`, preventing concurrent access to non-thread-safe Maven
internals. The parallel thread pool still handles task graph management,
build state recording, and result emission concurrently.

Co-authored-by: Claude Opus 4.6 &lt;noreply@anthropic.com&gt;
diff --git a/packages/maven/batch-runner-adapters/maven3/src/main/kotlin/dev/nx/maven/adapter/maven3/CachingMaven3Invoker.kt b/packages/maven/batch-runner-adapters/maven3/src/main/kotlin/dev/nx/maven/adapter/maven3/CachingMaven3Invoker.kt
@@ -71,6 +71,7 @@ class CachingMaven3Invoker(
         log.debug("CachingMaven3Invoker initialized")
     }
 
+    @Synchronized
     override fun invoke(
         args: List<String>,
         workingDir: File,
diff --git a/packages/maven/batch-runner-adapters/maven4/src/main/kotlin/dev/nx/maven/adapter/maven4/Maven4AdapterInvoker.kt b/packages/maven/batch-runner-adapters/maven4/src/main/kotlin/dev/nx/maven/adapter/maven4/Maven4AdapterInvoker.kt
@@ -46,6 +46,7 @@ class Maven4AdapterInvoker(
         log.debug("Maven4AdapterInvoker ready")
     }
 
+    @Synchronized
     override fun invoke(
         args: List<String>,
         workingDir: File,

Original file line number	Diff line number	Diff line change
`@@ -71,6 +71,7 @@ class CachingMaven3Invoker(`
`71`	`71`	`log.debug("CachingMaven3Invoker initialized")`
`72`	`72`	`}`
`73`	`73`
	`74`	`+ @Synchronized`
`74`	`75`	`override fun invoke(`
`75`	`76`	`args: List<String>,`
`76`	`77`	`workingDir: File,`
Original file line number	Diff line number	Diff line change
`@@ -46,6 +46,7 @@ class Maven4AdapterInvoker(`
`46`	`46`	`log.debug("Maven4AdapterInvoker ready")`
`47`	`47`	`}`
`48`	`48`
	`49`	`+ @Synchronized`
`49`	`50`	`override fun invoke(`
`50`	`51`	`args: List<String>,`
`51`	`52`	`workingDir: File,`