# Request for comments on approach to multithreaded work

**URL:** <https://discourse.julialang.org/t/request-for-comments-on-approach-to-multithreaded-work/72728>\
**Category:** General Usage\
**Tags:** multithreading, threads, channel\
**Created:** [December 7, 2021, 7:27pm UTC](https://discourse.julialang.org/t/request-for-comments-on-approach-to-multithreaded-work/72728 "2021-12-07T19:27:21Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![miguelbiron](https://avatars.discourse-cdn.com/v4/letter/m/258eb7/32.png) [@miguelbiron](https://discourse.julialang.org/u/miguelbiron)\
**Post date:** [December 7, 2021, 7:27pm UTC](https://discourse.julialang.org/t/request-for-comments-on-approach-to-multithreaded-work/72728/1 "2021-12-07T19:27:21Z")

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Hi,

I’m developing a multithreaded version of a piece of software and already have a working solution. I just want to check if there is a simpler way of doing it.

Basically, the problem can be reduced to this: suppose we need to complete `N` jobs. To do this, I have `nres` resources available—think of a machine in a factory (in my case it is a struct that is expensive to instantiate). Finally, there are `nthrds` workers that can operate those machines to complete one of the `N` jobs. Importantly, _only one worker may operate a resource at any time_.

Here’s a toy example that achieves exactly this

```julia
using Base.Threads

nthrds = nthreads() # number of threads (or workers)
nres = nthrds # number of resources on which threads can work
N = 20 # total number jobs that have to be completed

# channel containing id of the idle resources
const idle_res = Channel{Int}(nres)
foreach(i->put!(idle_res,i),1:nres) # initialize with all resources available

# function to complete a job using a given resource res
function do_work(res)
    sleep(0.5)
end

# do jobs using nthrds workers, taking and putting back idle resources
Threads.@threads for job in 1:N
    res = take!(idle_res) # take an idle resource. no other thread can now work on this resource
    do_work(res) # do job with the resource res
    println("thread ", threadid(), ": ", "completed job ", job, " using resource ", res)
    put!(idle_res, res) # mark resource as idle
end

```

My question is: **have I missed a simpler way of achieving this in Julia?**

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**Author:** ![goerch](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/goerch/32/29122_2.png) [@goerch](https://discourse.julialang.org/u/goerch)\
**Post date:** [December 7, 2021, 7:30pm UTC](https://discourse.julialang.org/t/request-for-comments-on-approach-to-multithreaded-work/72728/2 "2021-12-07T19:30:52Z")

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Looks already pretty nice to me!

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<div class="post-metadata">

**Author:** ![miguelbiron](https://avatars.discourse-cdn.com/v4/letter/m/258eb7/32.png) [@miguelbiron](https://discourse.julialang.org/u/miguelbiron)\
**Post date:** [December 8, 2021, 11:00pm UTC](https://discourse.julialang.org/t/request-for-comments-on-approach-to-multithreaded-work/72728/3 "2021-12-08T23:00:35Z")

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thanks for taking the time to review it!