Hey Ted, ----- Original Message ----- > From: "Ted Mielczarek" <[email protected]> > To: "Mozilla Platform Development" <[email protected]> > Sent: Monday, April 7, 2014 11:11:22 AM > Subject: Linux testing on single-core VMs nowadays > > I wanted to post about this because I don't think it's common knowledge > (I only just came to the realization today) and it has potential impact > on the effectiveness of our unit tests. > > Currently we run our Linux unit tests exclusively on Amazon EC2 > m1.medium[1] instances which have only one CPU core. Previously we used > to run Linux tests on in-house multicore hardware. This means that we're > testing different threading behavior now. In more concrete terms, a > threading bug[2] was found recently by AddressSanitizer but it only > manifested on the build machines (conveniently we still run some limited > xpcshell testing as part of `make check` as well as during packaging) > and not in our extensive unit tests running on the test machines. This > seems unfortunate. > > I'm not sure what the real impact of this is. Threading bugs can > certainly manifest on single-core machines, but the scheduling behavior > is different so they're likely to be different bugs. Is this an issue we > should address?
Personally, I think that the more ways we can test for threading issues the better. It seems to me that we should do some amount of testing on single core and multi-core. Then I suppose the question becomes how many cores? 2? 4? 8? Maybe we can cycle through some different number of cores so that we get coverage without duplicating everything? Threading issues probably don't happen all that often, but when they do happen they can be more difficult to track down. So being able to get some coverage on machines with different numbers of core seems useful (especially if the number of cores is readily available and logged along with the TBPL failures). Dave Hylands _______________________________________________ dev-platform mailing list [email protected] https://lists.mozilla.org/listinfo/dev-platform
