Workers aren't stopped when there's no more work to do

[giordano]

Mumble mumble mumble...if I run

julia> using ParallelTestRunner

julia> testsuite = Dict(
           "a" => :(),
           "b" => :(),
           "c" => :(),
           "d" => :(),
       );

julia> runtests(ParallelTestRunner, ["--jobs=4"]; testsuite);
Running 4 tests in parallel. If this is too many, specify the `--jobs=N` argument to the tests, or set the `JULIA_CPU_THREADS` environment variable.
               │          │ ──────────────── CPU ──────────────── │
Test  (Worker) │ Time (s) │ GC (s) │ GC % │ Alloc (MB) │ RSS (MB) │
b          (1) │     0.05 │   0.00 │  0.0 │       4.81 │   325.02 │
d          (2) │     0.05 │   0.00 │  0.0 │       4.81 │   324.19 │
a          (4) │     0.05 │   0.00 │  0.0 │       4.81 │   324.64 │
c          (3) │     0.05 │   0.00 │  0.0 │       4.81 │   323.78 │

Test Summary: | Total  Time
  Overall     |     0  4.1s
    SUCCESS

and then look at the output of

ps -ax | grep julia

I see all the four workers still alive. Doesn't look like they're actually stopped when they finish?

Originally posted by @giordano in #101 (comment)