Today I got a mysterious failure when using cpm on a travis-ci system. The build log with the failure can be seen here: https://travis-ci.org/eserte/bbbike/jobs/198528696#L5531

The error message ("Getopt/Long.pm did not return a true value") and the fact that the installation of Getopt::Long is reported a few log lines later suggests that the failure was caused by a use Getopt::Long while the installation of Getopt/Long.pm was in progress, so the calling script saw an incomplete file.

This is a new failure class which cannot happen in traditional serial installers. I don't have a good idea how to solve this. First, this possible problem should probably be documented. A possible fix could be to make sure that the installation step happens when no other build/configure/test processes run in parallel, but this would mean to slow down the whole installation process. Another possibility is to let these errors happen, but retry automatically once (after all, I am using cpm since some months and it's the first such failure). Finally it would probably be better to have the installation process more atomic. Currently ExtUtils::Install does a copy() of modules, but it would be more robust to copy to a temporary file on the destination filesystem, and then do an atomic rename(). Still it is not a real transaction if many files belonging to a distribution are to be installed, but at least incomplete file reads could not happen anymore.