[MESOS-9316] FsTest.Used is flaky

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.8.0
• Component/s: stout, test
• Labels: flaky flaky-test
• Sprint: Resource Mgmt R7 Sprint 32
• Assignee: Benjamin Mahler
• Reporter: Benjamin Bannier
• Created: 15/Oct/18 11:50
• Updated: 07/Nov/18 22:31
• Resolved: 07/Nov/18 22:31

Description

The stout test FsTest.Used is flaky,

[ RUN ] FsTest.Used
../3rdparty/stout/tests/os/filesystem_tests.cpp:817: Failure
 Expected: used.get() / b.f_frsize
 Which is: 1246447B
To be equal to: b.f_blocks - b.f_bfree
 Which is: 1246384
[ FAILED ] FsTest.Used (0 ms)

Looking at the test implementation this appears to be due to the test acquiring the two compared values non-atomically,

TEST_F(FsTest, Used)
{
 Try<Bytes> used = fs::used(".");
 ASSERT_SOME(used);

struct statvfs b;
 ASSERT_EQ(0, ::statvfs(".", &b));

// Check that the block counts match.
 EXPECT_EQ(used.get() / b.f_frsize, b.f_blocks - b.f_bfree);
}