Fix #738

Author: cowtowncoder

release-notes/CREDITS

@@ -215,3 +215,8 @@ Antibrumm@github:
 Francisco A. Lozano (flozano@github)
   * Contributed fix for #703 (see above)
    (2.5.2)
+
+Dylan Scott (dylanscott@github)
+  * Reported #738: #738: @JsonTypeInfo non-deterministically ignored in 2.5.1 (concurrency
+    issue)
+   (2.5.2)

release-notes/VERSION

@@ -19,6 +19,8 @@ Project: jackson-databind
  (reported by jkochaniak@github)
 #733: MappingIterator should move past errors or not return hasNext() == true
  (reported by Lorrin N, lorrin@github)
+#738: @JsonTypeInfo non-deterministically ignored in 2.5.1 (concurrency issue)
+ (reported by Dylan S, dylanscott@github)
 - Improvement to handling of custom `ValueInstantiator` for delegating mode; no more NPE
   if `getDelegateCreator()` returns null
 

src/main/java/com/fasterxml/jackson/databind/SerializerProvider.java

@@ -1111,12 +1111,13 @@ protected JsonSerializer<Object> _findExplicitUntypedSerializer(Class<?> runtime
      * Method that will try to construct a value serializer; and if
      * one is successfully created, cache it for reuse.
      */
-    protected JsonSerializer<Object> _createAndCacheUntypedSerializer(Class<?> type)
+    protected JsonSerializer<Object> _createAndCacheUntypedSerializer(Class<?> rawType)
         throws JsonMappingException
-    {        
+    {
+        JavaType type = _config.constructType(rawType);
         JsonSerializer<Object> ser;
         try {
-            ser = _createUntypedSerializer(_config.constructType(type));
+            ser = _createUntypedSerializer(type);
         } catch (IllegalArgumentException iae) {
             /* We better only expose checked exceptions, since those
              * are what caller is expected to handle
@@ -1155,8 +1156,15 @@ protected JsonSerializer<Object> _createAndCacheUntypedSerializer(JavaType type)
     protected JsonSerializer<Object> _createUntypedSerializer(JavaType type)
         throws JsonMappingException
     {
-        // 17-Feb-2013, tatu: Used to call deprecated method (that passed property)
-        return (JsonSerializer<Object>)_serializerFactory.createSerializer(this, type);
+        /* 27-Mar-2015, tatu: Wish I knew exactly why/what, but [databind#738]
+         *    can be prevented by synchronizing on cache (not on 'this', however,
+         *    since there's one instance per serialization).
+         *   Perhaps not-yet-resolved instance might be exposed too early to callers.
+         */
+        synchronized (_serializerCache) {
+            // 17-Feb-2013, tatu: Used to call deprecated method (that passed property)
+            return (JsonSerializer<Object>)_serializerFactory.createSerializer(this, type);
+        }
     }
 
     /**

src/test/java/com/fasterxml/jackson/failing/RaceCondition738Test.java

@@ -56,7 +56,7 @@ public HasSubTypes getHasSubTypes() {
      */
 
     public void testRepeatedly() throws Exception {
-        final int COUNT = 50;
+        final int COUNT = 2000;
         for (int i = 0; i < COUNT; i++) {
             runOnce(i, COUNT);
         }
@@ -88,10 +88,8 @@ public String call() throws Exception {
             JsonNode wrapped = tree.get("hasSubTypes");
 
             if (!wrapped.has("one")) {
-System.out.println("JSON wrong: "+json);
                 throw new IllegalStateException("Round #"+round+"/"+max+" ; missing property 'one', source: "+json);
             }
-System.out.println("JSON fine: "+json);
         }
     }