> On Dec 9, 2015, at 5:27 PM, Yvan Roux <yvan.r...@linaro.org> wrote: > > Hi, > > as it was raised in > https://gcc.gnu.org/ml/gcc-patches/2015-10/msg01540.html we experiment > random failures in gfortran validation when it is run in parallel (-j > 8). The issues occurs because of concurrent access to the same file, > the first two patches fixed some of them by changing the file names > used, but there are still remaining conflicts (6 usages of foo, 8 of > test.dat). This is easy to fix and I've a patch for that, but there is > another issue and I'd like to have your thoughts on it. > > There is a little bit more than 1000 testcases which use IO without > explicit file names, ~150 use scratches (a temporary file named > gfortrantmp + 6 extra char is created) and the others, which only > specify the io unit number, use a file named fort.NN with NN the > number of the io unit. We see conflicts on these generated files, as > lot of testcases use the same number, the most used are: > > 10 => 150 > 99 => 70 > 6 => 31 > 11 => 27 > 1 => 23 > > I started to change the testcases to use scratches when it is possible > and before finding that there is that many to fix, and I also had > conflicts on the generated scratch names. The options I see to fix > that are: > > 1- Move all these testcases into an IO subdir and change the testsuite > to avoid parallelism in that directory. > 2- Use scratches when possible and improve libgfortran file name > generation, I don't know well fortran but is it possible to change the > file name patterns for scratches and io unit files ? > 3- Change the io unit numbers used, as it was suggested on irc, but I > find it a bit painful to maintain. > > Any comments are welcome.
I have also investigated several races on I/O in the gfortran testsuite, and my preference is to go with [1]. Specifically, if a fortran test does I/O with filenames that can clash with some other test, then the test should be located in a sub-directory of gfortran.dg testsuite that runs its test in-order. -- Maxim Kuvyrkov www.linaro.org
