Re: [e4-dev] Unit testing multi-threaded code

[John Arthorne <John_Arthorne@xxxxxxxxxx>]

Hi Nigel, some thoughts:

 - The most important thing is
putting all blocking code into jobs/threads and not run anything that may
deadlock in the main test thread because it can kill a whole test suite.
All tests should be forking off the real test, and then the main test waits
with a bounded timeout for completion.
 - There is some basic infrastructure
in the org.eclipse.core.tests.harness bundle, such as TestJob and TestBarrier.
TestBarrier is used heavily in platform tests, but you could use the Semaphore
classes in java.util.concurrent with similar effect. 
 - Essentially using a semaphore
lets you strictly control the order of execution between multiple threads,
making the test predictable and nearly equivalent to a single-threaded
test. Tests need to be clearly repeatable wherever possible, rather than
just running a concurrent activity 100 times and maybe it will fail, maybe
not.
 - Having tests rely on an unapproved
library that everyone running tests will need to install separately is
a  no-go. If it is really valuable we can enter a CQ and get it added
as a proper dependency.

Good luck, concurrency testing is really
hard!

John




From:      
 Nigel Westbury <nigelipse@xxxxxxxxxx>
To:      
 e4-dev@xxxxxxxxxxx,

Date:      
 03/04/2014 07:52 AM
Subject:    
   [e4-dev] Unit
testing multi-threaded code
Sent by:    
   e4-dev-bounces@xxxxxxxxxxx

---

I was wondering if there were any recommendations
on how we write unit 
tests for multi-threading code.  I am writing tests for 
https://bugs.eclipse.org/bugs/show_bug.cgi?id=425704
(making obserables 
thread-safe).

I have used https://code.google.com/p/multithreadedtc/
very effectively 
on other projects.  It is published under the BSD license, which we
probably can't commit, so would that mean users would have to install 
manually to run the tests?
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