Apache softwares are well tested. Each of them has as many LOC of xUnit test codes as production codes, and the test codes are run frequently on Apache Buildbot.
However, unfortunately these xUnit tests tend to be "flaky". i.e. they can fail non-deterministically. Even when tests are flaky on Buildbot, it is hard to debug for developers because failure cannot be reproduced by just running tests repeatedly. So flaky tests can be a very troublesome threat for quality assuarance of Apache softwares.
In this presentation, Akihiro Suda will show the "flakiness" of several Apache softwares (e.g. Hadoop), and discuss why they are so flaky.
Additionally, he will also introduce his open-source debugging tool, named "Earthquake". This tool can easily reproduce failures of flaky tests by increasing the non-deternimism of the thread scheduling for unmodified xUnit tests.
Software engineer at NTT. Active contributor to Docker (non-maintainer). Talked about flaky tests in distributed systems at FOSDEM 2016 and ApacheCon Core North America 2016. (tool: github.com/osrg/namazu)