bring back test

python/src/test/java/org/apache/zeppelin/python/IPythonInterpreterTest.java

@@ -286,6 +286,49 @@ public class IPythonInterpreterTest extends BasePythonInterpreterTest {
             context.out.toInterpreterResultMessage().get(1).getType());
   }
 
+  @Test
+  public void testIpython_shouldNotHang_whenCallingAutoCompleteAndInterpretConcurrently()
+      throws InterpreterException,
+      InterruptedException, TimeoutException, ExecutionException {
+    tearDown();
+    Properties properties = initIntpProperties();
+    startInterpreter(properties);
+    final String code = "import time\n"
+        + "print(1)\n"
+        + "time.sleep(10)\n"
+        + "print(2)";
+    final String base = "time.";
+
+    // The goal of this test is to ensure that concurrent interpret and complete
+    // will not make execute hang forever.
+    ExecutorService pool = Executors.newFixedThreadPool(2);
+    FutureTask<InterpreterResult> interpretFuture =
+        new FutureTask(new Callable() {
+          @Override
+          public Object call() throws Exception {
+            return interpreter.interpret(code, getInterpreterContext());
+          }
+        });
+    FutureTask<List<InterpreterCompletion>> completionFuture =
+        new FutureTask(new Callable() {
+          @Override
+          public Object call() throws Exception {
+            return interpreter.completion(base, base.length(), null);
+          }
+        });
+
+    pool.execute(interpretFuture);
+    // we sleep to ensure that the paragraph is running
+    Thread.sleep(3000);
+    pool.execute(completionFuture);
+
+    // We ensure that running and auto completion are not hanging.
+    InterpreterResult res = interpretFuture.get(20000, TimeUnit.MILLISECONDS);
+    List<InterpreterCompletion> autoRes = completionFuture.get(1000, TimeUnit.MILLISECONDS);
+    assertTrue(res.code().name().equals("SUCCESS"));
+    assertTrue(autoRes.size() > 0);
+  }
+
   @Test
   public void testGrpcFrameSize() throws InterpreterException, IOException {
     tearDown();