# Task not runnable error
**URL:** https://discourse.julialang.org/t/task-not-runnable-error/73506
**Category:** General Usage
**Tags:** task
**Created:** [December 22, 2021, 6:50pm UTC](https://discourse.julialang.org/t/task-not-runnable-error/73506 "2021-12-22T18:50:32Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Lilith](https://discourse.julialang.org/u/Lilith)
#### Post date: [December 22, 2021, 6:50pm UTC](https://discourse.julialang.org/t/task-not-runnable-error/73506/1 "2021-12-22T18:50:32Z")
Hi folks, I have a task that says it’s runnable, but I get a task not runnable error:
```julia
julia> task = @task readline(stdin)
Task (runnable) @0x000000010f798010
julia> yield(task)
julia> task
Task (runnable) @0x000000010f798010
julia> yield(task)
ERROR: yield: Task not runnable
Stacktrace:
[1] error(s::String)
@ Base ./error.jl:33
[2] yield (repeats 2 times)
@ ./task.jl:737 [inlined]
[3] top-level scope
@ REPL[4]:1
julia> task
Task (runnable) @0x000000010f798010
```
What is going on here?
---
### Author:  [@tkf](https://discourse.julialang.org/u/tkf)
#### Post date: [December 22, 2021, 9:48pm UTC](https://discourse.julialang.org/t/task-not-runnable-error/73506/2 "2021-12-22T21:48:18Z")
I’d say the printing of the task is misleading here. `(runnable)` does not mean “the user can schedule it.”
Also, I think it’s very tricky to use `yield` for a task that is already started. In particular, the code in the OP is not correct. If you want to know when `yield` can be called on the task that is already started, have a look at [https://github.com/JuliaLang/julia/pull/41270](https://github.com/JuliaLang/julia/pull/41270) which discusses when `schedule` can be used for the task that is already started. Using `yield` is even more strict since you have to know that the context switch has been completed. I think this requires knowing the worker thread that executed the said task and then that the worker thread is now executing another task.
In short: I don’t think you’d want to do this.
---
### Author:  [@Lilith](https://discourse.julialang.org/u/Lilith)
#### Post date: [December 22, 2021, 11:04pm UTC](https://discourse.julialang.org/t/task-not-runnable-error/73506/3 "2021-12-22T23:04:37Z")
I think the zero argument `yield()` proved the best solution for my use case.
---
### Author:  [@tkf](https://discourse.julialang.org/u/tkf)
#### Post date: [December 23, 2021, 1:38am UTC](https://discourse.julialang.org/t/task-not-runnable-error/73506/4 "2021-12-23T01:38:37Z")
Yes, zero-arg `yield()` is a good API for telling the scheduler to try other tasks.