Here is a report of the current races. http://paste.ubuntu.com/11256308/
On Thu, May 21, 2015 at 11:10 AM, Tim Penhey <tim.pen...@canonical.com> wrote: > Thanks Dave for this great write up. > > In order to drive the data races to zero, and make a soon to be added CI > test as voting, I propose that as folks are writing tests in packages, > races in at least that file, an possibly that package should be fixed. > > Tim > > On 21/05/15 12:12, David Cheney wrote: >> Hello, >> >> TL;DR - juju has lots of problems with data races, please test your >> code with the -race flag to ensure it doesn't get worse while we try >> to fix the problem. >> >> Longer version: >> >> In debugging https://bugs.launchpad.net/bugs/1456398 I found that >> there are multiple data races in the Juju code base. It's been long >> suspected that the test's are racy, PatchValue is super easy to >> introduce a race if all the workers started by a test have not exited >> before the suite's tear down function runs. >> >> However, more serious races have been discovered, such as >> https://bugs.launchpad.net/bugs/1456857 which affects code all the way >> back to 1.22. >> >> Why is a data race bad ? >> >> Ok, so you're looking at https://bugs.launchpad.net/bugs/1456857 and >> you're thinking, so maybe the tls code accidentally uses the wrong >> certificate for a little bit, how bad is that? >> >> The problem is data races affect the integrity of the structures that >> the garbage collector uses. In the example above replacing the >> certificate means one CPU can see the new value, and another >> potentially the old value. When it comes to to run the gc, depending >> on which CPU walks that chain of pointers it may think that the old >> certificate is still live, or the new certificate is unreachable -- >> and boom that memory is marked as free and the certificate corrupted. >> >> The short version is: there are no safe data races, and Juju is not >> reliable until they have all been fixed. >> >> How to run the race detector ? >> >> The race detector comes with Go and is available by adding the -race >> flag to invocations of go test, so what was >> >> go test github.com/juju/juju/... >> >> becomes >> >> go test -race github.com/juju/juju/... >> >> The downside of this is the race detector has significant overhead, at >> least 2x, so tests will be even slower. >> >> Thanks >> >> Dave >> > -- Juju-dev mailing list Juju-dev@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/juju-dev
