Access to worker stdout/stderr

[Socob]

It would be nice to have some control over where the worker’s stdout/stderr goes. Currently, there is no (documented) way to access this, and output is just silently dropped. To some extent, this can be done via Worker.proc, but presumably this should not be relied on?

[fonsp]

Thanks for the feedback!

I think this stdout should be shown on the terminal of the server, just like Distributed. You said that you can access this with .proc. Do you know how to relay this to the server terminal?

Distributed adds From Worker 5: before each stdout line. Is that easy to implement?

[Socob]

I think this stdout should be shown on the terminal of the server, just like Distributed.

To clarify, do you mean that this is how it currently works (which it doesn’t, as far as I can tell), or that the behavior should be changed to this in the future?

Distributed does this:

function redirect_worker_output(ident, stream)
    t = @async while !eof(stream)
        line = readline(stream)
        if startswith(line, "      From worker ")
            # stdout's of "additional" workers started from an initial worker on a host are not available
            # on the master directly - they are routed via the initial worker's stdout.
            println(line)
        else
            println("      From worker $(ident):\t$line")
        end
    end
    errormonitor(t)
end

The same could be done here, with stream being Worker.proc. I actually find the prefix " From worker " quite annoying in Distributed though (it can’t be turned off), so if this is implemented, I’d argue in favor of at least making it configurable.