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Simplify the GC.gc interface #34303

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Merged
merged 1 commit into from
Jan 8, 2020
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Simplify the GC.gc interface #34303

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25 changes: 8 additions & 17 deletions base/gcutils.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -49,29 +49,20 @@ Module with garbage collection utilities.
"""
module GC

# @enum-like structure
struct CollectionType
x::Int
end
Base.cconvert(::Type{Cint}, collection::CollectionType) = Cint(collection.x)

const Auto = CollectionType(0)
const Full = CollectionType(1)
const Incremental = CollectionType(2)

"""
GC.gc(full::Bool=true)
GC.gc(collection::CollectionType)
GC.gc()
GC.gc(full::Bool)

Perform garbage collection. The argument `full` determines whether a full, but more costly
collection is performed. Otherwise, heuristics are used to determine which type of
collection is needed. For exact control, pass an argument of type `CollectionType`.
Perform garbage collection. The argument `full` determines the kind of collection: A full
collection scans all objects, while an incremental collection only scans so-called young
objects and is much quicker. If called without an argument, heuristics are used to determine
which type of collection is needed.

!!! warning
Excessive use will likely lead to poor performance.
"""
gc(full::Bool=true) = ccall(:jl_gc_collect, Cvoid, (Cint,), full)
gc(collection::CollectionType) = ccall(:jl_gc_collect, Cvoid, (Cint,), collection)
gc() = ccall(:jl_gc_collect, Cvoid, (Cint,), 0)
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Sorry, read this too quickly since it was supposed to be not a breaking change. This was a breaking change (as in CI has been broken for a week now because of this PR):

Suggested change
gc() = ccall(:jl_gc_collect, Cvoid, (Cint,), 0)
gc() = ccall(:jl_gc_collect, Cvoid, (Cint,), 1)

Please, please, please be careful about merging PRs that fail on CI (as this one did).

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@StefanKarpinski StefanKarpinski Jan 10, 2020 •
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Even if they are not wrapped in a type or user-facing, it might be good for this code to use locally-defined constants to make the code easier to read. My understanding is that these are the values:

const GC_AUTO = 0
const GC_FULL = 1
const GC_INCR = 2

Is that correct? If so, it would be good to define these constants and then use them in the method definitions. I guess the issue is that the default previously was GC_FULL rather than GC_AUTO?

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Crap, sorry for that, I had been too accustomed to win32 failing recently...

Even if they are not wrapped in a type or user-facing, it might be good for this code to use locally-defined constants to make the code easier to read.

Agreed, I'll see about improving that next week.

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Crap, sorry for that, I had been too accustomed to win32 failing recently...

💯 I wouldn't blame you here. CI needs to be fixed. The situation is atrocious.

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Yeah, I rather regret not merging #33741 to fix a major contributor months ago, but we really need to prioritize getting the other known fixes merged (#34336, #33785, and #34242 at least) too.

gc(full::Bool) = ccall(:jl_gc_collect, Cvoid, (Cint,), full ? 1 : 2)

"""
GC.enable(on::Bool)
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1 change: 0 additions & 1 deletion test/misc.jl
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Expand Up @@ -792,7 +792,6 @@ end
@testset "GC utilities" begin
GC.gc()
GC.gc(true); GC.gc(false)
GC.gc(GC.Auto); GC.gc(GC.Full); GC.gc(GC.Incremental)

GC.safepoint()
end