A test to reproduce Gson concurrency bug. See issue 63.

gson/src/test/java/com/google/gson/functional/ConcurrencyTest.java

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+/*
+ * Copyright (C) 2008 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.gson.functional;
+
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import junit.framework.TestCase;
+
+import com.google.gson.Gson;
+
+/**
+ * Tests for ensuring Gson thread-safety.
+ * 
+ * @author Inderjeet Singh
+ * @author Joel Leitch
+ */
+public class ConcurrencyTest extends TestCase {
+  private Gson gson;
+
+  @Override
+  protected void setUp() throws Exception {
+    super.setUp();
+    gson = new Gson();
+  }
+
+  /**
+   * Source-code based on
+   * http://groups.google.com/group/google-gson/browse_thread/thread/563bb51ee2495081
+   */
+  public void testSingleThread() { 
+    MyObject myObj = new MyObject("hello", "world", 42); 
+    for (int i = 0; i < 10; i++) { 
+      gson.toJson(myObj); 
+    } 
+  } 
+
+  /**
+   * Source-code based on
+   * http://groups.google.com/group/google-gson/browse_thread/thread/563bb51ee2495081
+   */
+  public void testMultiThread() throws InterruptedException {
+    final CountDownLatch startLatch = new CountDownLatch(1);
+    final CountDownLatch finishedLatch = new CountDownLatch(10);
+    final AtomicBoolean failed = new AtomicBoolean(false);
+    ExecutorService executor = Executors.newFixedThreadPool(10);
+    for (int taskCount = 0; taskCount < 10; taskCount++) {
+      executor.execute(new Runnable() {
+        public void run() {
+          MyObject myObj = new MyObject();
+          try {
+            startLatch.await();
+            for (int i = 0; i < 10; i++) {
+              String json = gson.toJson(myObj);
+            }
+          } catch (Throwable t) {
+            failed.set(true);
+          } finally {
+            finishedLatch.countDown();
+          }
+        }
+      });
+    }
+    startLatch.countDown();
+    finishedLatch.await();
+    assertFalse(failed.get());
+  }
+
+  private static class MyObject {
+    private String a;
+    private String b;
+    private int i;
+
+    MyObject() {
+      this("hello", "world", 42);
+    }
+
+    public MyObject(String a, String b, int i) {
+      this.a = a;
+      this.b = b;
+      this.i = i;
+    }
+  }
+}