David Rowley <dgrowleyml(at)gmail(dot)com> writes:
> Right now we start 1 backend for each test in a parallel group then
> wait for the final backend to complete before running the next group.
> Is a particular reason for it to work that way?
There are a whole lot of cases where test Y depends on an earlier test X.
Some of those dependencies are annotated in parallel_schedule, but I fear
most are not.
If we had a full list of such dependencies then we could imagine building
a job scheduler that would dispatch any script that has no remaining
dependencies.
The cases where "script X can't run concurrently with script Y" are
also problematic. It's not as easy to discover those through testing,
since it might happen to work depending on timing.
regards, tom lane