Fix flaky MultiFragmentTest.partitionedOutputWithLargeInput (facebook…

…incubator#9147)

Summary:
Fix the flaky test by creating leaf task with more memory capacity. The flaky
test now passed 1000 iterations in Meta internal

Pull Request resolved: facebookincubator#9147

Reviewed By: Yuhta, mbasmanova

Differential Revision: D55055257

Pulled By: xiaoxmeng

fbshipit-source-id: 37c169fed5971bbde8f18c50792c7e6c4c1e8251

velox/exec/tests/MultiFragmentTest.cpp

@@ -579,7 +579,6 @@ TEST_F(MultiFragmentTest, partitionedOutputWithLargeInput) {
   // This test exercises splitting up the input both from the edges and the
   // middle as it ends up splitting it into at least 3.
   setupSources(1, 30'000);
-  const int64_t kRootMemoryLimit = 1 << 20; // 1MB
   // Single Partition
   {
     auto leafTaskId = makeTaskId("leaf", 0);
@@ -588,8 +587,7 @@ TEST_F(MultiFragmentTest, partitionedOutputWithLargeInput) {
             .values(vectors_)
             .partitionedOutput({}, 1, {"c0", "c1", "c2", "c3", "c4"})
             .planNode();
-    auto leafTask =
-        makeTask(leafTaskId, leafPlan, 0, nullptr, kRootMemoryLimit);
+    auto leafTask = makeTask(leafTaskId, leafPlan, 0, nullptr, 4 << 20);
     leafTask->start(1);
     auto op = PlanBuilder().exchange(leafPlan->outputType()).planNode();