Synchronize the String dedupe cache.

Without explicit synchronization, an internal iterator can be corrupted and result in an infinite loop on WeakHashMap#get calls. Fixes #3171: Hang with threads and Hash[]= on unfrozen keys.
jruby · Jul 23, 2015 · e88911e · e88911e
1 parent e6a26e3
commit e88911e
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/core/src/main/java/org/jruby/Ruby.java b/core/src/main/java/org/jruby/Ruby.java
@@ -177,6 +177,7 @@
 import java.security.SecureRandom;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.EnumMap;
 import java.util.EnumSet;
 import java.util.HashMap;
@@ -5105,7 +5106,7 @@ public void addToObjectSpace(boolean useObjectSpace, IRubyObject object) {
      *
      * Access must be synchronized.
      */
-    private WeakHashMap<RubyString, WeakReference<RubyString>> dedupMap = new WeakHashMap<RubyString, WeakReference<RubyString>>();
+    private Map<RubyString, WeakReference<RubyString>> dedupMap = Collections.synchronizedMap(new WeakHashMap<RubyString, WeakReference<RubyString>>());
 
     private static final AtomicInteger RUNTIME_NUMBER = new AtomicInteger(0);
     private final int runtimeNumber = RUNTIME_NUMBER.getAndIncrement();