Fix DynamicFromMap object pool synchronization

Author: haitaoli

ReactAndroid/src/main/java/com/facebook/react/bridge/DynamicFromMap.java

@@ -9,13 +9,18 @@
 
 import javax.annotation.Nullable;
 
-import android.support.v4.util.Pools;
+import android.support.v4.util.Pools.SimplePool;
 
 /**
  * Implementation of Dynamic wrapping a ReadableMap.
  */
 public class DynamicFromMap implements Dynamic {
-  private static final Pools.SimplePool<DynamicFromMap> sPool = new Pools.SimplePool<>(10);
+  private static final ThreadLocal<SimplePool<DynamicFromMap>> sPool = new ThreadLocal<SimplePool<DynamicFromMap>>() {
+    @Override
+    protected SimplePool<DynamicFromMap> initialValue() {
+      return new SimplePool<>(10);
+    }
+  };
 
   private @Nullable ReadableMap mMap;
   private @Nullable String mName;
@@ -24,7 +29,7 @@ public class DynamicFromMap implements Dynamic {
   private DynamicFromMap() {}
 
   public static DynamicFromMap create(ReadableMap map, String name) {
-    DynamicFromMap dynamic = sPool.acquire();
+    DynamicFromMap dynamic = sPool.get().acquire();
     if (dynamic == null) {
       dynamic = new DynamicFromMap();
     }
@@ -37,7 +42,7 @@ public static DynamicFromMap create(ReadableMap map, String name) {
   public void recycle() {
     mMap = null;
     mName = null;
-    sPool.release(this);
+    sPool.get().release(this);
   }
 
   @Override