R CMD check freezes when a test contains parallel calls

[gvegayon]

I've been trying to switch some of my R packages to the tinytest framework. In some of them, I use the parallel package, i.e. parallel::makeCluster() and that doesn't seem to work with tinytest. To show this, I've created a small toy package with a single function: hello_parallel, which creates a cluster object cl and calls parallel::clusterEvalQ(cl, "hello"). Running tinytest::test_all works fine, but R CMD check freezes.

Here is the repo where I put the toy package:

https://github.com/USCbiostats/tinytesttest

Here is one example of tinytest failing (freezing) during R CMD check:

https://travis-ci.org/USCbiostats/tinytesttest/builds/584236824#L728

I had to stop this build after 9 minutes running.

Also, a similar issue happens when I call R using system calls, e.g. system2("R", ...).

[gvegayon]

And here is a travis build that timeout b/c of no output in the last 10 minutes
https://travis-ci.org/USCbiostats/tinytesttest/builds/584238339

[markvanderloo]

Thanks, I've now confirmed this locally. Bit of a riddle at the moment, I have to dig through some documentation to see where this comes from. Also, big thanks for setting up the test package.

[markvanderloo]

Ok it seems to be similar to this issue in testthat. I managed to avoid the trouble by setting

Sys.setenv("R_TESTS"="")

in the beginning of the test file.

Note: you do not need to unset the envvar at the end because tinytest does this automatically for you after running the test file (so R_TESTS only has a different value from the original one while this particular file runs).

It is a hack and a workaround but maybe you can now at least keep working while I look for a real solution.

[gvegayon]

Yes, that seems to work fine. Thanks!

[markvanderloo]

Fixed, tested with tinytesttest, also affects #37 0ab0659

[gvegayon]

Awesome, thanks!