[THRIFT-4469] isServing is not thread safe

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.9.3, 0.10.0, 0.11.0, 0.12.0
• Fix Version/s: 0.13.0
• Component/s: Java - Library
• Labels: easyfix
• Assignee: James E. King III
• Reporter: Robert Joseph Evans
• Created: 22/Jan/18 22:21
• Updated: 16/Oct/19 22:27
• Resolved: 03/Jan/19 12:23

Description

We have some integration tests in storm were we create a TServer and call serve on it in a background thread, because it is a blocking call.

Then in the main thread we wait for up to 10 seconds for isServing to return success with a 100ms sleep in between each call.

I don't know if this is a java bug or what, but in some not so rare cases isServing does not return true during the entire 10 seconds and the test fails. The test prints out a stack trace when this happens and the background thread running the server is always at

https://github.com/apache/thrift/blob/b636ffb613ab49e0f037fbe696d28a4b17a72c5f/lib/java/src/org/apache/thrift/server/AbstractNonblockingServer.java#L95

happily serving.

So either we got very unlucky many times and it takes just a few ms longer than 10 seconds to come up some times, and < 1 sec other times, or java is doing something strange some of the time, and because Server.isServing is not volatile the checking thread caches a copy of it in a register and never updates it during the 10 seconds of the test run.

Even if it is a java bug, which I could argue probably is, it would be good to make isServing volatile.

Issue Links

• links to: GitHub Pull Request #1668