# Create multiple tasks in a loop
**URL:** https://discourse.julialang.org/t/create-multiple-tasks-in-a-loop/71701
**Category:** General Usage
**Tags:** multithreading, task
**Created:** [November 18, 2021, 6:18am UTC](https://discourse.julialang.org/t/create-multiple-tasks-in-a-loop/71701 "2021-11-18T06:18:41Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@Bossax](https://discourse.julialang.org/u/Bossax)
#### Post date: [November 18, 2021, 6:18am UTC](https://discourse.julialang.org/t/create-multiple-tasks-in-a-loop/71701/1 "2021-11-18T06:18:41Z")
Hi everyone,
I am trying to create multiple tasks in a forr loop using @eval. Here is a block of code
```julia
f(k) = begin sleep(1)
println("t$k is done")
end
begin
for k in 1:4
@eval $(Symbol(:t,k)) = @task f(k)
end
sleep(1)
for k in 1:4
@eval schedule($(Symbol(:t,k)))
end
end
```
I want to assing the value k into the f() function when creating a task However, Julia throws back error
```julia
UndefVarError: k not defined
```
The error is caused by this line
```julia
@eval $(Symbol(:t,k)) = @task f(k)
```
How to correct this?
Any help would be appreciated!
Sitthichat
---
### Author:  [@ffevotte](https://discourse.julialang.org/u/ffevotte)
#### Post date: [November 18, 2021, 8:39am UTC](https://discourse.julialang.org/t/create-multiple-tasks-in-a-loop/71701/2 "2021-11-18T08:39:53Z")
Is there a particular reason why you’d want to have your tasks in separate `t1`, `t2`, … variables instead of putting them in an array and referencing them as `t[1]`, `t[2]`, …?
If it works for you, an array-based solution would IMO be more Julian; it could look like this:
```julia
julia> function f(k)
sleep(1)
println("task $k is done")
end
f (generic function with 1 method)
julia> tasks = [@task f(k) for k in 1:4]
4-element Vector{Task}:
Task (runnable) @0x00007f10aa7b70a0
Task (runnable) @0x00007f10aa7b71f0
Task (runnable) @0x00007f10aa7b7340
Task (runnable) @0x00007f10aa7b7490
julia> sleep(1)
julia> for t in tasks
schedule(t)
end
task 1 is done
task 2 is done
task 3 is done
task 4 is done
```
---
### Author:  [@wormholestds9](https://discourse.julialang.org/u/wormholestds9)
#### Post date: [November 18, 2021, 9:03am UTC](https://discourse.julialang.org/t/create-multiple-tasks-in-a-loop/71701/3 "2021-11-18T09:03:23Z")
You could insert $ in front of k so that it should be f($k).
It worked for me.
@eval $(Symbol(:t,k)) = @task f($k)
---
### Author:  [@Bossax](https://discourse.julialang.org/u/Bossax)
#### Post date: [November 19, 2021, 1:50am UTC](https://discourse.julialang.org/t/create-multiple-tasks-in-a-loop/71701/5 "2021-11-19T01:50:29Z")
Indeed! This looks more Julian. Thanks so much
---
### Author:  [@wormholestds9](https://discourse.julialang.org/u/wormholestds9)
#### Post date: [November 19, 2021, 5:18pm UTC](https://discourse.julialang.org/t/create-multiple-tasks-in-a-loop/71701/6 "2021-11-19T17:18:32Z")
You can even collapse them into a single instruction:
schedule.(@task f(k) for k=1:4)
or
foreach(schedule, (@task f(k) for k=1:4))
---
### Author:  [@ffevotte](https://discourse.julialang.org/u/ffevotte)
#### Post date: [November 19, 2021, 7:54pm UTC](https://discourse.julialang.org/t/create-multiple-tasks-in-a-loop/71701/7 "2021-11-19T19:54:18Z")
In order to create a task and schedule it immediately (which was not the case in the OP), it is more direct to use `@async`:
```julia
tasks = [@async f(k) for k in 1:n]
```