multi-thread support

[rana]

Multi-thread support post v1.3 would be helpful.
Can't use without it.
Thank you

[KristofferC]

I think support for running a callback when a task gets scheduled to stop / start would be needed for this, Otherwise, for example if you have

const to = TimerOutput()
function foo()
    @timeit to "some section"
        some_work()
    end
end

for i in 1:200
    Threads.@spawn foo()
end

creating 200 tasks running concurrently doing work in foo then I don't see a way to give a sensible result for how much time is spent inside foo unless I can only record the times where the task is actually executing.

[racinmat]

Maybe it would be useful to add some merging function so I could have one TimerOutput per thread, and then sum them up to see how they all performed.
When I tried the approach above, I obtained some race conditions, probably, and crashes like:

ERROR: TaskFailedException:
UndefRefError: access to undefined reference
Stacktrace:
 [1] getindex at .\array.jl:744 [inlined]
 [2] pop! at .\array.jl:1080 [inlined]
 [3] pop!(::TimerOutput) at C:\Users\racinsky\.julia\packages\TimerOutputs\7Id5J\src\TimerOutput.jl:74
 [4] macro expansion at C:\Users\racinsky\.julia\packages\TimerOutputs\7Id5J\src\TimerOutput.jl:218 [inlined]
 [5] load_shas(::SubArray{String,1,Array{String,1},Tuple{UnitRange{Int64}},true}) at C:\Projects\SkunkAV\scripts\bench_schema_creation.jl:93
 [6] (::ThreadTools.var"#8#10"{Tuple{SubArray{String,1,Array{String,1},Tuple{UnitRange{Int64}},true}},typeof(load_shas)})() at .\threadingconstructs.jl:113
Stacktrace:
 [1] wait at .\task.jl:251 [inlined]
 [2] fetch at .\task.jl:266 [inlined]
 [3] _broadcast_getindex_evalf at .\broadcast.jl:630 [inlined]
 [4] _broadcast_getindex at .\broadcast.jl:603 [inlined]
 [5] getindex at .\broadcast.jl:563 [inlined]
 [6] copy at .\broadcast.jl:853 [inlined]
 [7] materialize(::Base.Broadcast.Broadcasted{Base.Broadcast.DefaultArrayStyle{1},Nothing,typeof(fetch),Tuple{Array{Task,1}}}) at .\broadcast.jl:819
 [8] tmap(::Function, ::Base.Iterators.PartitionIterator{Array{String,1}}) at C:\Users\racinsky\.julia\packages\ThreadTools\5hMgn\src\ThreadTools.jl:61
 [9] top-level scope at none:0

[antoine-levitt]

I think a barebones support for this where basically every logging call is prefixed by if Threads.threadid() == 1 would already be super helpful for most workflows.

[ericphanson]

as a simple alternative, you could try my (not yet registered) https://github.com/ericphanson/TrackingTimers.jl, which supports the same @timeit API as TimerOutputs and allows multiprocess/multithreading, but doesn't keep track of nesting or anything like that (making parallelism very easy to support).

[rana]

Nice @ericphanson

[IanButterworth]

It requires a bit of manual organization but this seems to work for straightforwardly structured multi-threading #128

[oschulz]

If I understand #128 correctly this could be closed now?