# IOError: could not spawn \<...\>: argument list too long

**URL:** <https://discourse.julialang.org/t/ioerror-could-not-spawn-argument-list-too-long/43728>\
**Category:** New to Julia\
**Created:** [July 26, 2020, 11:02pm UTC](https://discourse.julialang.org/t/ioerror-could-not-spawn-argument-list-too-long/43728 "2020-07-26T23:02:48Z")\
**Posts on this page:** 4\
**Page:** 2

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**Author:** ![aplavin](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/aplavin/32/222056_2.png) [@aplavin](https://discourse.julialang.org/u/aplavin)\
**Post date:** [November 5, 2020, 7:19pm UTC](https://discourse.julialang.org/t/ioerror-could-not-spawn-argument-list-too-long/43728/21 "2020-11-05T19:19:00Z")

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It’s not only threads by the way: the same happens with `async`.

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**Author:** ![giordano](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/giordano/32/2166_2.png) [@giordano](https://discourse.julialang.org/u/giordano)\
**Post date:** [November 5, 2020, 7:33pm UTC](https://discourse.julialang.org/t/ioerror-could-not-spawn-argument-list-too-long/43728/22 "2020-11-05T19:33:37Z")

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The call syntax for the thread-safe executable product will be slightly different: instead of

```julia
command() do path
    run(`$(path) ...`)
end

```

you’d do

```julia
run(`$(command()) ...`)

```

The old (thread-unsafe) syntax is always available, the new (thread-safe) one only in Julia v1.6+ (and that will become the preferred one in the future)

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<div class="post-metadata">

**Author:** ![aplavin](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/aplavin/32/222056_2.png) [@aplavin](https://discourse.julialang.org/u/aplavin)\
**Post date:** [November 5, 2020, 7:41pm UTC](https://discourse.julialang.org/t/ioerror-could-not-spawn-argument-list-too-long/43728/23 "2020-11-05T19:41:53Z")

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And what about existing jll packages? Will they only have a way to call them thread/async-safely after explicit action, or some automatic process will happen?

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**Author:** ![giordano](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/giordano/32/2166_2.png) [@giordano](https://discourse.julialang.org/u/giordano)\
**Post date:** [November 5, 2020, 7:42pm UTC](https://discourse.julialang.org/t/ioerror-could-not-spawn-argument-list-too-long/43728/24 "2020-11-05T19:42:49Z")

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All packages generated from Yggdrasil in the last 4-6 weeks have already this feature

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