Fix MultiFragmentTest.compression (facebookincubator#9639)

Summary:
The test was flaky because the task created later has the same task id. If the previous task does not get deleted in time before the second task comes in, the test will fail. The fix is to give the tasks different names

facebookincubator#9453

Pull Request resolved: facebookincubator#9639

Reviewed By: xiaoxmeng

Differential Revision: D56651191

Pulled By: tanjialiang

fbshipit-source-id: 3bdfbe9e7fbc30ac94f92788dd2c37194d5a99b5

velox/exec/tests/MultiFragmentTest.cpp

@@ -2024,7 +2024,6 @@ TEST_F(MultiFragmentTest, compression) {
                                 .values({data}, false, kNumRepeats)
                                 .partitionedOutput({}, 1)
                                 .planNode();
-  const auto producerTaskId = "local://t1";
 
   const auto plan = test::PlanBuilder()
                         .exchange(asRowType(data->type()))
@@ -2034,7 +2033,9 @@ TEST_F(MultiFragmentTest, compression) {
   const auto expected =
       makeRowVector({makeFlatVector<int64_t>(std::vector<int64_t>{6000000})});
 
-  const auto test = [&](float minCompressionRatio, bool expectSkipCompression) {
+  const auto test = [&](const std::string& producerTaskId,
+                        float minCompressionRatio,
+                        bool expectSkipCompression) {
     PartitionedOutput::testingSetMinCompressionRatio(minCompressionRatio);
     auto producerTask = makeTask(producerTaskId, producerPlan);
     producerTask->start(1);
@@ -2061,8 +2062,8 @@ TEST_F(MultiFragmentTest, compression) {
     }
   };
 
-  test(0.7, false);
-  test(0.0000001, true);
+  test("local://t1", 0.7, false);
+  test("local://t2", 0.0000001, true);
 }
 
 } // namespace