# How to make sure a task interrupts when it takes too long

**URL:** https://discourse.julialang.org/t/how-to-make-sure-a-task-interrupts-when-it-takes-too-long/115939
**Category:** General Usage
**Tags:** question, package, benchmarktools
**Created:** [June 20, 2024, 4:19pm UTC](https://discourse.julialang.org/t/how-to-make-sure-a-task-interrupts-when-it-takes-too-long/115939 "2024-06-20T16:19:42Z")
**Posts on this page:** 2
**Page:** 1

<div class="post-metadata">

### Author: ![arnerob](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/arnerob/32/49522_2.png) [@arnerob](https://discourse.julialang.org/u/arnerob)
#### Post date: [June 20, 2024, 4:19pm UTC](https://discourse.julialang.org/t/how-to-make-sure-a-task-interrupts-when-it-takes-too-long/115939/1 "2024-06-20T16:19:42Z")

</div>

So I’m trying to do some experiments on how long some algorithms take.  
Whenever an experiment takes longer than some set time-out I want to stop it and go to another one.  
The algorithms I’m trying to time are pretty involved and use IterTools, JuMP and CPLEX.  
I tried to make a minimum working example, but the code below works fine for me.

```julia
using BenchmarkTools

function runBenchmark(bench, timeout=10)
    task = @async run(bench)
    elapsed_time = 0.0
    check_interval = 0.1 # Check every 0.1 seconds

    while elapsed_time < timeout
        sleep(check_interval)
        if istaskdone(task)
            return fetch(task)
        end
        elapsed_time += check_interval
    end

    @async Base.throwto(task, InterruptException())
    return nothing
end

for k in 15:-5:5
  bench=@benchmarkable sleep($k)  
  println(runBenchmark(bench))
end

```

The problem is that when I replace bench by the complicated algorithm, then it doesn’t interrupt it for some reason. It returns the output with a timed value above the time-out. I’m trying to understand how this happens and find and how to fix it.

The algorithm I’m testing sometimes takes long time because it iterates over a large cartesian product (using IterTools.product) and computes a linear program for each of them.

I guess I could write a small bash script with “timeout” that runs julia scripts, but maybe understanding the problem would help me find a cleaner solution?

---

<div class="post-metadata">

### Author: ![Satvik](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/satvik/32/20486_2.png) [@Satvik](https://discourse.julialang.org/u/Satvik)
#### Post date: [June 20, 2024, 4:42pm UTC](https://discourse.julialang.org/t/how-to-make-sure-a-task-interrupts-when-it-takes-too-long/115939/2 "2024-06-20T16:42:41Z")

</div>

If you want to interrupt a task, it needs `yield()` statements somewhere. `sleep` already has them, so it’s interruptible.

For example, this can’t be interrupted:

```julia
function foo()
       i = 0
       while true
           i += 1
       end
end

@async foo()

```

But this can:

```julia
function foo()
       i = 0
       while true
           i += 1
           yield()
       end
end
@async foo()

```

Per the documentation, yield will “Switch to the scheduler to allow another scheduled task to run. A task that calls this function is still runnable, and will be restarted immediately if there are no other runnable tasks.”