Observable plotted dataframe cann't be updated from task

[olegshtch]

I'm trying to update dataframe from background task

using DataFrames, Observables, Interact, Mux, Plots, WebIO

obs = Observables.Observable{DataFrame}(DataFrames.DataFrame(x = 2:3, y = 1:2))
on(obs) do o
	println("On get data")
end

schedule(
	Task(
        	function ()
			println("Waiting for data")
			sleep(60)
	   	        println("Ready!")
			obs[] = DataFrames.DataFrame(x = 2:4, y = 1:3)
		end
	)
)
println("Launched getting data")
function createLayout(req)
	println(req)

	plt = Interact.@map plot((&obs).x ,(&obs).y, label="Model output")
	wdg = Widget(["df" => obs])
	@layout! wdg vbox(plt)
end

function serveLayout(port::Int)
	try
		fetch(WebIO.webio_serve(Mux.page("/", createLayout), port))
	catch e
		if isa(e, IOError)
			# sleep and then try again
			sleep(0.1)
			serveLayout(port)
		else
			throw(e)
		end
	end
end
println("Starting server")
serveLayout(8080)

If I open page before Ready! I will see plot 2:3, 1:2 and when background task finishes I get error:

$ julia 1.jl 
Launched getting data
Starting server
Waiting for data
Dict{Any,Any}(:query => "",:method => "GET",:params => Dict{Any,Any}(),:path => SubString{String}[],:cookies => HTTP.Cookies.Cookie[],:uri => HTTP.URI("/"),:data => UInt8[],:headers => Pair{SubString{String},SubString{String}}["Host" => "localhost:8080", "User-Agent" => "...", "Accept" => "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8", "Accept-Language" => "ru,en-US;q=0.7,en;q=0.3", "Accept-Encoding" => "gzip, deflate", "Connection" => "keep-alive", "Upgrade-Insecure-Requests" => "1"])
Ready!
On get data
MethodError: no method matching (::var"#7#9")(::DataFrame)
The applicable method may be too new: running in world age 26857, while current world is 26861.
Closest candidates are:
  #7(::Any) at none:0 (method too new to be called from this world context.)
Stacktrace:
 [1] (::Observables.var"#16#17"{var"#7#9",Observable{Any}})(::DataFrame) at /home/olegshtch/.julia/packages/Observables/qCJWB/src/Observables.jl:152
 [2] (::Observables.var"#g#15"{Observables.var"#16#17"{var"#7#9",Observable{Any}},Tuple{Observable{DataFrame}}})(::DataFrame) at /home/olegshtch/.julia/packages/Observables/qCJWB/src/Observables.jl:136
 [3] #setindex!#1(::Observables.var"#2#4", ::typeof(setindex!), ::Observable{DataFrame}, ::DataFrame) at /home/olegshtch/.julia/packages/Observables/qCJWB/src/Observables.jl:87
 [4] setindex!(::Observable{DataFrame}, ::DataFrame) at /home/olegshtch/.julia/packages/Observables/qCJWB/src/Observables.jl:83
 [5] (::var"#5#6")() at /home/olegshtch/julia/1.jl:14

If I open page after Ready! I get plot 2:4, 1:3 without errors.

I've tried to replace

obs[] = DataFrames.DataFrame(x = 2:4, y = 1:3)

with

invokelatest(setindex!, obs, DataFrames.DataFrame(x = 2:4, y = 1:3))

but in this case listeners aren't called and plot doesn't changed.

Julia 1.3.1

  [a93c6f00] DataFrames v0.20.0
  [c601a237] Interact v0.10.3
  [a975b10e] Mux v0.7.1
  [510215fc] Observables v0.2.3
  [91a5bcdd] Plots v0.28.4
  [0f1e0344] WebIO v0.8.13

[olegshtch]

Looks like invokelatest proveded here from other module. It works if I use Base.invokelatest.