[kudu] 01/04: test: re-deflake TabletServerQuiescingITest

[gr...@apache.org]

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granthenke pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/kudu.git

commit 148c169d46d2cdccc7434e827162552279bc3e4a
Author: Andrew Wong <aw...@cloudera.com>
AuthorDate: Wed Mar 4 17:41:32 2020 -0800

    test: re-deflake TabletServerQuiescingITest
    
    Commit bc2efa1ae97fcc4e592c93d38592206d48d6f8f5 undid some of the
    deflaking done in 6e4dd49 by increasing the number of read threads.
    
    This puts us back at using a single reader, which, while may not always
    yield active scanners, should be significantly less flaky.
    
    I ran this 100 times in TSAN mode and saw no failures, compared to the
    20% flakiness reported by our test dashboard.
    
    Change-Id: I598c0f0a9a665691bc675920d8dc5a0d272be72e
    Reviewed-on: http://gerrit.cloudera.org:8080/15365
    Reviewed-by: Adar Dembo <ad...@cloudera.com>
    Tested-by: Kudu Jenkins
---
 src/kudu/integration-tests/tablet_server_quiescing-itest.cc | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/kudu/integration-tests/tablet_server_quiescing-itest.cc b/src/kudu/integration-tests/tablet_server_quiescing-itest.cc
index 921915c..f01cfb1 100644
--- a/src/kudu/integration-tests/tablet_server_quiescing-itest.cc
+++ b/src/kudu/integration-tests/tablet_server_quiescing-itest.cc
@@ -378,8 +378,9 @@ TEST_F(TServerQuiescingITest, TestQuiescingToolBasics) {
   auto* ts = cluster_->mini_tablet_server(0);
   auto rw_workload = CreateFaultIntolerantRWWorkload();
   rw_workload->Setup();
-  // Spawn a bunch of read threads so we'll be more likely to see scanners.
-  rw_workload->set_num_read_threads(10);
+  // NOTE: if this value is too high, this test can become flaky, since the
+  // degrees of freedom in the number of active scanners will be high.
+  rw_workload->set_num_read_threads(1);
   ASSERT_FALSE(ts->server()->quiescing());
   const auto& master_addr = cluster_->mini_master()->bound_rpc_addr().ToString();
   // First, call the start tool a couple of times.