Debugger does not break on @bp when using threads

[herzfeldd]

First of all, thanks for this great tool!

Unfortunately, break points don't appear to function correctly when using Threads.@threads. In particular, break points are never hit, even when explicitly placed in the code. bp on error seems to appropriately break if there is an error, but the stack trace just shows a call to ccall(:jl_threading_run, Cvoid, (Any,), threadsfor_fun), not the stack for the actual thread. I am happy to break this into two separate issues if they should be tracked separately.

Here is a MWE:

module ModuleFoo
    import Debugger
    function foo()
        println("Running with $(Threads.nthreads()) threads.")
        Threads.@threads for i = 1:Threads.nthreads()
            foo_with_bp()
        end
    end

    function foo_with_bp()
        Debugger.@bp
        error("I should never get here")
    end
end

using Debugger
@run ModuleFoo.foo()

Note: This fails to break on @bp even when you aren't explicitly using more than on thread (i.e., does not break on @bp even when JULIA_NUM_THREADS=1).

Version Info:
julia version 1.4.2
[31a5f54b] Debugger v0.6.6

[KristofferC]

I think this is expected for now. The threading system goes into the Julia runtime where the interpreter loses track of it.

[davidanthoff]

See also JuliaDebug/JuliaInterpreter.jl#413.

[KristofferC]

Closing in favor of the upstream issue.