Merge pull request #2709 from tianshuang/race_condition

Fix a race condition caused by other threads calling mapper methods while mappedStatements are being constructed

src/main/java/org/apache/ibatis/session/Configuration.java

@@ -25,6 +25,7 @@
 import java.util.Map;
 import java.util.Properties;
 import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.BiFunction;
 
 import org.apache.ibatis.binding.MapperRegistry;
@@ -998,7 +999,7 @@ protected void checkLocallyForDiscriminatedNestedResultMaps(ResultMap rm) {
     }
   }
 
-  protected static class StrictMap<V> extends HashMap<String, V> {
+  protected static class StrictMap<V> extends ConcurrentHashMap<String, V> {
 
     private static final long serialVersionUID = -4950446264854982944L;
     private final String name;
@@ -1055,6 +1056,15 @@ public V put(String key, V value) {
       return super.put(key, value);
     }
 
+    @Override
+    public boolean containsKey(Object key) {
+      if (key == null) {
+        return false;
+      }
+
+      return super.get(key) != null;
+    }
+
     @Override
     public V get(Object key) {
       V value = super.get(key);