fix concurrent modification

jpbempel · jpbempel · commit 536ee7b3bdee · 2024-08-19T12:57:30.000+02:00
need to clone the list in classNamesBySourceFile Map to avoid
concurrent modification of it while registering a new class
diff --git a/dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/agent/ClassesToRetransformFinder.java b/dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/agent/ClassesToRetransformFinder.java
@@ -89,7 +89,10 @@ Trie getAllChangedClasses(ConfigurationComparer comparer) {
 
   private void processAdditionalClasses(String sourceFile, Trie changedClasses) {
     sourceFile = stripPackagePath(sourceFile);
-    List<String> additionalClasses = classNamesBySourceFile.get(sourceFile);
+    // need to clone the list to avoid concurrent modification during iteration
+    List<String> additionalClasses =
+        classNamesBySourceFile.computeIfPresent(
+            sourceFile, (k, classNames) -> new ArrayList<>(classNames));
     if (additionalClasses == null) {
       return;
     }
