In case anybody is following along… I streamlined the test a little bit and profiled it. You need a file server.jl with these contents:
function server()
while true
s = String(readavailable(stdin))
s[1] == 'q' && break
println(stdout,"[Server via stdout]: received $(s[1])")
println(stderr,"[Server via stderr]: received $(s[1])")
flush(stdout)
flush(stderr)
end
end
server()
exit()
Then, run this code:
using Profile
function async_reader(io::IO)::Channel
ch = Channel(1)
task = @async begin
buf = ""
while isempty(buf) || buf[end] != '\n'
data = String(readavailable(io))
buf *= data
end
put!(ch,buf)
end
bind(ch, task)
return ch
end
function init()
pin = Pipe()
pout = Pipe()
perr = Pipe()
proc = run(pipeline(`julia -L server.jl`,
stdin = pin, stdout = pout, stderr = perr),
wait = false)
close.([pout.in, perr.in, pin.out])
return pin, pout, perr
end
function runtest(times, pin, pout, perr)
for k=1:times
write(pin,"a\n")
flush(pin)
ch_out = async_reader(pout)
ch_err = async_reader(perr)
out = take!(ch_out)
err = take!(ch_err)
end
write(pin,"q\n")
nothing
end
Profile.init(delay=0.001)
Profile.clear();
p = init();
runtest(1,p...);
p = init();
@profile runtest(1000,p...)
Profile.print()
In Linux, the resulting profile is
20 ./task.jl:259; (::getfield(REPL, Symbol("##26#27")){RE...
20 ...lib/v1.1/REPL/src/REPL.jl:117; macro expansion
20 ...lib/v1.1/REPL/src/REPL.jl:85; eval_user_input(::Any, ::REPL.REPLBackend)
20 ./boot.jl:328; eval(::Module, ::Any)
5 ./REPL[4]:3; runtest(::Int64, ::Pipe, ::Pipe, ::Pipe)
5 ./strings/io.jl:165; write
5 ./gcutils.jl:87; macro expansion
5 ./io.jl:225; unsafe_write
5 ./stream.jl:901; unsafe_write(::Base.PipeEndpoint, ::...
5 ./stream.jl:845; uv_write(::Base.PipeEndpoint, ::Ptr...
5 ./stream.jl:877; uv_write_async(::Base.PipeEndpoint...
1 ./REPL[4]:5; runtest(::Int64, ::Pipe, ::Pipe, ::Pipe)
1 ./REPL[2]:3; async_reader(::Pipe)
1 ./task.jl:262; macro expansion
1 ./boot.jl:384; Type
1 ./boot.jl:384; Type
1 ./REPL[4]:6; runtest(::Int64, ::Pipe, ::Pipe, ::Pipe)
1 ./REPL[2]:3; async_reader(::Pipe)
1 ./task.jl:262; macro expansion
1 ./boot.jl:384; Type
1 ./boot.jl:384; Type
8 ./REPL[4]:7; runtest(::Int64, ::Pipe, ::Pipe, ::Pipe)
8 ./channels.jl:315; take!
8 ./channels.jl:362; take_buffered(::Channel{Any})
8 ./event.jl:46; wait(::Condition)
8 ./event.jl:256; wait()
8 ./libuv.jl:100; process_events
2 ./REPL[4]:8; runtest(::Int64, ::Pipe, ::Pipe, ::Pipe)
2 ./channels.jl:315; take!
2 ./channels.jl:362; take_buffered(::Channel{Any})
2 ./event.jl:46; wait(::Condition)
2 ./event.jl:246; wait()
2 ./libuv.jl:98; process_events
561 ./task.jl:259; (::getfield(Main, Symbol("##5#6")){Pipe...
561 ./REPL[2]:6; macro expansion
561 ./io.jl:243; readavailable
561 ./stream.jl:829; readavailable
561 ./stream.jl:368; wait_readnb(::Base.PipeEndpoint, ::In...
561 ./event.jl:46; wait(::Condition)
538 ./event.jl:246; wait()
538 ./libuv.jl:98; process_events
1 ./stream.jl:523; uv_alloc_buf(::Ptr{Nothing}, ::UInt6...
1 ./stream.jl:507; alloc_buf_hook(::Base.PipeEndpoint,...
1 ./stream.jl:489; alloc_request(::Base.GenericIOBuff...
1 ./iobuffer.jl:312; ensureroom
1 ./iobuffer.jl:320; ensureroom
1 ./array.jl:812; _growend!
23 ./event.jl:256; wait()
23 ./libuv.jl:100; process_events
In Windows, the profile is much longer. I’ll copy only the lines that correspond to ./task.jl:259:
2261 .\task.jl:259; (::getfield(Main, Symbol("##3#4")){Pipe,Channel{Any}})()
2259 .\REPL[2]:6; macro expansion
2259 .\io.jl:243; readavailable
2259 .\stream.jl:829; readavailable
1 .\stream.jl:367; wait_readnb(::Base.PipeEndpoint, ::Int64)
1 .\stream.jl:715; start_reading
401 .\stream.jl:368; wait_readnb(::Base.PipeEndpoint, ::Int64)
400 .\event.jl:46; wait(::Condition)
1 .\event.jl:245; wait()
1 .\abstractarray.jl:863; isempty
1 .\event.jl:266; ==
389 .\event.jl:246; wait()
389 .\libuv.jl:98; process_events
3 .\stream.jl:516; uv_alloc_buf(::Ptr{Nothing}, ::UInt64, ::Ptr{Nothing})
2 .\stream.jl:519; uv_alloc_buf(::Ptr{Nothing}, ::UInt64, ::Ptr{Nothing})
1 .\sysimg.jl:18; getproperty
3 .\stream.jl:523; uv_alloc_buf(::Ptr{Nothing}, ::UInt64, ::Ptr{Nothing})
3 .\stream.jl:581; uv_readcb(::Ptr{Nothing}, ::Int64, ::Ptr{Nothing})
3 .\stream.jl:564; (::getfield(Base, Symbol("#readcb_specialized#489")))(::Base.PipeEndpoint, :...
3 .\event.jl:62; notify
3 .\event.jl:62; notify
3 .\event.jl:62; #notify#442
3 .\event.jl:68; notify(::Condition, ::Nothing, ::Bool, ::Bool)
3 .\event.jl:129; schedule
3 .\event.jl:132; #schedule#443(::Bool, ::Function, ::Task, ::Nothing)
3 .\sysimg.jl:19; setproperty!(::Task, ::Symbol, ::Nothing)
2 .\event.jl:255; wait()
1 .\event.jl:187; try_yieldto(::typeof(Base.ensure_rescheduled), ::Base.RefValue{Task})
1 .\event.jl:199; try_yieldto(::typeof(Base.ensure_rescheduled), ::Base.RefValue{Task})
1 .\sysimg.jl:19; setproperty!(::Task, ::Symbol, ::Nothing)
8 .\event.jl:256; wait()
8 .\libuv.jl:100; process_events
2 .\stream.jl:523; uv_alloc_buf(::Ptr{Nothing}, ::UInt64, ::Ptr{Nothing})
1 .\stream.jl:507; alloc_buf_hook(::Base.PipeEndpoint, ::UInt64)
1 .\stream.jl:489; alloc_request(::Base.GenericIOBuffer{Array{UInt8,1}}, ::UInt64)
1 .\iobuffer.jl:312; ensureroom
1 .\iobuffer.jl:314; ensureroom
1855 .\stream.jl:372; wait_readnb(::Base.PipeEndpoint, ::Int64)
1855 .\stream.jl:737; stop_reading
1 .\stream.jl:374; wait_readnb(::Base.PipeEndpoint, ::Int64)
1 .\sysimg.jl:18; getproperty
1 .\stream.jl:377; wait_readnb(::Base.PipeEndpoint, ::Int64)
1 .\libuv.jl:57; unpreserve_handle(::Base.PipeEndpoint)
1 .\abstractdict.jl:598; getindex
1 .\abstractdict.jl:594; get
1 .\sysimg.jl:18; getproperty
1 .\REPL[2]:7; macro expansion
1 .\strings\basic.jl:229; *
1 .\strings\substring.jl:180; string(::String, ::String)
1 .\strings\string.jl:60; _string_n
1 .\int.jl:49; macro expansion
5 .\task.jl:294; task_done_hook(::Task)
2 .\abstractarray.jl:1866; foreach(::getfield(Base, Symbol("##453#454")){Task}, ::Array{Any,1})
2 .\task.jl:294; (::getfield(Base, Symbol("##453#454")){Task})(::getfield(Base, Symbol("##599#600"...
2 .\channels.jl:197; #599
2 .\channels.jl:230; close_chnl_on_taskdone(::Task, ::WeakRef)
1 .\abstractdict.jl:598; getindex(::IdDict{Any,Any}, ::Any)
1 .\abstractdict.jl:594; get
2 .\task.jl:295; task_done_hook(::Task)
1 .\abstractdict.jl:605; delete!(::IdDict{Any,Any}, ::Any)
So, there is a lot more going on when running under Windows. I don’t understand the internals well enought to know if this points at a solution, though.