# How to stop a task started with \`@schedule\`

**URL:** <https://discourse.julialang.org/t/how-to-stop-a-task-started-with-schedule/7632>\
**Category:** New to Julia\
**Created:** [December 8, 2017, 7:10pm UTC](https://discourse.julialang.org/t/how-to-stop-a-task-started-with-schedule/7632 "2017-12-08T19:10:52Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![airpmb](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/airpmb/32/7826_2.png) [@airpmb](https://discourse.julialang.org/u/airpmb)\
**Post date:** [December 8, 2017, 7:10pm UTC](https://discourse.julialang.org/t/how-to-stop-a-task-started-with-schedule/7632/1 "2017-12-08T19:10:52Z")

</div>

Suppose I do something like the following:

```julia
i = 0
@schedule begin
  global i
  sleep(1)
  @show i
   i += 1
end

```

If I don’t grab the return value of `@schedule` (or for that matter even if I do), is there any sane way to stop the task from running? I say any sane way because I noticed that, at least for this example, I could effectively stop it by indirectly causing an exception to be raised:

```julia
julia> i = nothing
ERROR (unhandled task failure): MethodError: no method matching +(::Void, ::Int64)
Closest candidates are:
  +(::Any, ::Any, ::Any, ::Any...) at operators.jl:424
  +(::Complex{Bool}, ::Real) at complex.jl:247
  +(::Char, ::Integer) at char.jl:40
  ...
Stacktrace:
 [1] macro expansion at ./REPL[86]:5 [inlined]
 [2] (::##1770#1771)() at ./event.jl:73
julia> 

```

I did find [#6283](https://github.com/JuliaLang/julia/issues/6283) which sounds like it would add what I’m asking about, but in the meantime is there a better way to achieve this?

Incidentally (and in case it suggests another approach), my actual use case for `@schedule` is for periodically emitting printouts to follow the status of an optimization being performed with NLopt.jl – AFAICT there’s no way to request it to provide such trace printouts and you have to build something into your objective function to accomplish this (yet – [NLopt #16](https://github.com/JuliaOpt/NLopt.jl/issues/16)).

---

<div class="post-metadata">

**Author:** ![jonathanBieler](https://avatars.discourse-cdn.com/v4/letter/j/82dd89/32.png) [@jonathanBieler](https://discourse.julialang.org/u/jonathanBieler)\
**Post date:** [December 8, 2017, 8:24pm UTC](https://discourse.julialang.org/t/how-to-stop-a-task-started-with-schedule/7632/2 "2017-12-08T20:24:17Z")

</div>

Only way I know of is:

```julia
t = @schedule begin
    sleep(10)
end

@schedule Base.throwto(t,InterruptException())

```