# Why has simple threading using \`threadid\` become so complex in v1.12...?

**URL:** <https://discourse.julialang.org/t/why-has-simple-threading-using-threadid-become-so-complex-in-v1-12/129135>\
**Category:** Performance\
**Created:** [May 19, 2025, 9:09am UTC](https://discourse.julialang.org/t/why-has-simple-threading-using-threadid-become-so-complex-in-v1-12/129135 "2025-05-19T09:09:39Z")\
**Posts on this page:** 1\
**Showing post:** 30

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**Author:** ![lmiq](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/lmiq/32/18314_2.png) [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Post date:** [August 14, 2025, 11:37pm UTC](https://discourse.julialang.org/t/why-has-simple-threading-using-threadid-become-so-complex-in-v1-12/129135/30 "2025-08-14T23:37:22Z")

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See [No more 1st class support for Threads? [thread-local storage] - #34 by foobar\_lv2](https://discourse.julialang.org/t/no-more-1st-class-support-for-threads-thread-local-storage/131535/34)

Also note that if one does not need to store the task-local buffer and does not need the indices, this can be simplified to:

```julia-auto
model = fit(Model, data)
# split work in n=nthreads() chunks
@threads for chunk in ChunkSplitters.chunks(1:1000; n=Threads.nthreads())
   m = deepcopy(model)
   for item in chunk
       predict!(m, newdata)
   end
end

```

Which makes pretty clear that the only `n` copies of `model` are created, and that there is not race condition among their uses.

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