Fix for http://code.google.com/p/mybatis/issues/detail?id=578 . Deadlock in CachingExecutor and pooled datasources. Thanks to Chris Dadej.

Author: emacarron

pom.xml

@@ -57,6 +57,10 @@
       <name>Arkadi Shishlov</name>
       <email>[email protected]</email>
     </contributor>
+    <contributor>
+      <name>Chris Dadej</name>
+      <email>[email protected]</email>
+    </contributor>
     <contributor>
       <name>Franta Mejta</name>
       <email>[email protected]</email>

src/main/java/org/apache/ibatis/executor/CachingExecutor.java

@@ -87,20 +87,19 @@ public <E> List<E> query(MappedStatement ms, Object parameterObject, RowBounds r
       flushCacheIfRequired(ms);
       if (ms.isUseCache() && resultHandler == null) { 
         ensureNoOutParams(ms, key, parameterObject, boundSql);
-        cache.getReadWriteLock().readLock().lock();
-        try {
-          @SuppressWarnings("unchecked")
-          List<E> cachedList = dirty ? null : (List<E>) cache.getObject(key);
-          if (cachedList != null) {
-            return cachedList;
-          } else {
-            List<E> list = delegate.<E> query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);
-            tcm.putObject(cache, key, list);
-            return list;
+        if (!dirty) {
+          cache.getReadWriteLock().readLock().lock();
+          try {
+            @SuppressWarnings("unchecked")
+            List<E> cachedList = (List<E>) cache.getObject(key);
+            if (cachedList != null) return cachedList;
+          } finally {
+            cache.getReadWriteLock().readLock().unlock();
           }
-        } finally {
-          cache.getReadWriteLock().readLock().unlock();
         }
+        List<E> list = delegate.<E> query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);
+        tcm.putObject(cache, key, list); // issue #578. Query must be not synchronized to prevent deadlocks
+        return list;
       }
     }
     return delegate.<E>query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);