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Set max_methods for lock and unlock to 1 #60803

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Merged
KristofferC merged 1 commit into from
Jan 30, 2026
Merged

Set max_methods for lock and unlock to 1 #60803

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2 changes: 2 additions & 0 deletions base/io.jl
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Expand Up @@ -31,7 +31,9 @@ struct SystemError <: Exception
end

lock(::IO) = nothing
typeof(lock).name.max_methods = UInt8(1)
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@nsajko nsajko Jan 30, 2026

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What happens if a method of lock gets defined and a method instance gets compiled/inferred before you change max_methods here? Would it cause miscompilation?

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@JamesWrigley JamesWrigley Jan 30, 2026

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From grepping the code and looking at the include order in Base.jl I think this is where the function is declared the first time, so that should not happen.

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@nsajko nsajko Jan 30, 2026

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What if some other PR switches the code around a bit, sometime in the future? Will we get miscompilation silently?

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@KristofferC KristofferC Jan 30, 2026

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This seems like a separate concern from this PR since this code pattern is already used in other places already. Maybe move the discussion to a separate issue?

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@nsajko nsajko Jan 30, 2026 •
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I don't think it is a separate issue. The pattern of modifying max_methods for a function is only used for a few examples currently:

So if it becomes common to modify max_methods for various functions all over the code base, I think then we would actually need to start worrying about stuff like this.

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@KristofferC KristofferC Jan 30, 2026

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Yes, since it is already in the code base, a dedicated issue makes more sense rather than comments on a PR.

unlock(::IO) = nothing
typeof(unlock).name.max_methods = UInt8(1)

"""
reseteof(io)
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