Cannot serialize during __init__

[willow-ahrens]

On Version 1.11.2, serialization during __init__ results in a KeyError. Consider the following package:

module Foo

using Serialization

struct Bar
    x::Int
end

function __init__()
    mktemp() do path, io
        serialize(io, Bar(42))
    end
end

end # module Foo

Running using Foo results in:

ERROR: InitError: KeyError: key Foo not found
Stacktrace:
  [1] getindex
    @ ./iddict.jl:98 [inlined]
  [2] macro expansion
    @ ./lock.jl:273 [inlined]
  [3] root_module_key
    @ ./loading.jl:2420
  [4] serialize_mod_names
    @ ~/.julia/juliaup/julia-1.11.2+0.aarch64.apple.darwin14/share/julia/stdlib/v1.11/Serialization/src/Serialization.jl:390
  [5] serialize
    @ ~/.julia/juliaup/julia-1.11.2+0.aarch64.apple.darwin14/share/julia/stdlib/v1.11/Serialization/src/Serialization.jl:402 [inlined]
  [6] serialize_type_data
    @ ~/.julia/juliaup/julia-1.11.2+0.aarch64.apple.darwin14/share/julia/stdlib/v1.11/Serialization/src/Serialization.jl:595
  [7] serialize_type
    @ ~/.julia/juliaup/julia-1.11.2+0.aarch64.apple.darwin14/share/julia/stdlib/v1.11/Serialization/src/Serialization.jl:627
  [8] serialize_any
    @ ~/.julia/juliaup/julia-1.11.2+0.aarch64.apple.darwin14/share/julia/stdlib/v1.11/Serialization/src/Serialization.jl:0
  [9] serialize
    @ ~/.julia/juliaup/julia-1.11.2+0.aarch64.apple.darwin14/share/julia/stdlib/v1.11/Serialization/src/Serialization.jl:680 [inlined]
 [10] serialize
    @ ~/.julia/juliaup/julia-1.11.2+0.aarch64.apple.darwin14/share/julia/stdlib/v1.11/Serialization/src/Serialization.jl:807 [inlined]
 [11] #1
    @ ~/Projects/Foo/src/Foo.jl:11 [inlined]
 [12] mktemp
    @ ./file.jl:790
 [13] mktemp
    @ ./file.jl:788 [inlined]
 [14] __init__()
    @ Foo ~/Projects/Foo/src/Foo.jl:10
 [15] run_module_init(mod::Module, i::Int64)
    @ Base ./loading.jl:1378
 [16] register_restored_modules(sv::Core.SimpleVector, pkg::Base.PkgId, path::String)
    @ Base ./loading.jl:1366
 [17] _include_from_serialized(pkg::Base.PkgId, path::String, ocachepath::String, depmods::Vector{Any}, ignore_native::Nothing; register::Bool)
    @ Base ./loading.jl:1254
 [18] _include_from_serialized (repeats 2 times)
    @ ./loading.jl:1210 [inlined]
 [19] _require_search_from_serialized(pkg::Base.PkgId, sourcepath::String, build_id::UInt128, stalecheck::Bool; reasons::Dict{String, Int64}, DEPOT_PATH::Vector{String})
    @ Base ./loading.jl:2057
 [20] _require(pkg::Base.PkgId, env::String)
    @ Base ./loading.jl:2527
 [21] __require_prelocked(uuidkey::Base.PkgId, env::String)
    @ Base ./loading.jl:2388
 [22] #invoke_in_world#3
    @ ./essentials.jl:1089 [inlined]
 [23] invoke_in_world
    @ ./essentials.jl:1086 [inlined]
 [24] _require_prelocked(uuidkey::Base.PkgId, env::String)
    @ Base ./loading.jl:2375
 [25] macro expansion
    @ ./loading.jl:2314 [inlined]
 [26] macro expansion
    @ ./lock.jl:273 [inlined]
 [27] __require(into::Module, mod::Symbol)
    @ Base ./loading.jl:2271
 [28] #invoke_in_world#3
    @ ./essentials.jl:1089 [inlined]
 [29] invoke_in_world
    @ ./essentials.jl:1086 [inlined]
 [30] require(into::Module, mod::Symbol)
    @ Base ./loading.jl:2260
during initialization of module Foo

[willow-ahrens]

I think this may be related to #56329 or perhaps #56077

[nsajko]

using Foo throws on v1.11, but not on v1.10 or v1.12. Perhaps a backportable fix exists on v1.12?

[willow-ahrens]

Ah, but on 1.12 we cannot read the file that is written. Consider:

module Foo

using Serialization

struct Bar
    x::Int
end

function __init__()
    if isfile("./hello")
        open("./hello", "r") do io
            println(deserialize(io))
        end
    end
    open("./hello", "w") do io
        serialize(io, Bar(42))
    end
end

end # module Foo

On the second run, this yields:

ERROR: InitError: KeyError: key Base.PkgId(Base.UUID("af919380-6608-446a-b46d-163e99a4cdff"), "Foo") not found
Stacktrace:
  [1] getindex
    @ ./dict.jl:477 [inlined]
  [2] macro expansion
    @ ./lock.jl:294 [inlined]
  [3] root_module(key::Base.PkgId)
    @ Base ./loading.jl:2563
  [4] deserialize_module(s::Serialization.Serializer{IOStream})
    @ Serialization ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.12/Serialization/src/Serialization.jl:1019
  [5] handle_deserialize(s::Serialization.Serializer{IOStream}, b::Int32)
    @ Serialization ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.12/Serialization/src/Serialization.jl:921
  [6] deserialize(s::Serialization.Serializer{IOStream})
    @ Serialization ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.12/Serialization/src/Serialization.jl:839
  [7] deserialize_datatype(s::Serialization.Serializer{IOStream}, full::Bool)
    @ Serialization ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.12/Serialization/src/Serialization.jl:1508
  [8] handle_deserialize(s::Serialization.Serializer{IOStream}, b::Int32)
    @ Serialization ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.12/Serialization/src/Serialization.jl:892
  [9] deserialize(s::Serialization.Serializer{IOStream})
    @ Serialization ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.12/Serialization/src/Serialization.jl:839
 [10] handle_deserialize(s::Serialization.Serializer{IOStream}, b::Int32)
    @ Serialization ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.12/Serialization/src/Serialization.jl:899
 [11] deserialize(s::Serialization.Serializer{IOStream})
    @ Serialization ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.12/Serialization/src/Serialization.jl:839
 [12] handle_deserialize(s::Serialization.Serializer{IOStream}, b::Int32)
    @ Serialization ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.12/Serialization/src/Serialization.jl:945
 [13] deserialize
    @ ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.12/Serialization/src/Serialization.jl:839 [inlined]
 [14] deserialize(s::IOStream)
    @ Serialization ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.12/Serialization/src/Serialization.jl:826
 [15] (::Foo.var"#__init__##0#__init__##1")(io::IOStream)
    @ Foo ~/Projects/Foo/src/Foo.jl:12
 [16] open(::Foo.var"#__init__##0#__init__##1", ::String, ::Vararg{String}; kwargs::@Kwargs{})
    @ Base ./io.jl:410
 [17] open
    @ ./io.jl:407 [inlined]
 [18] __init__()
    @ Foo ~/Projects/Foo/src/Foo.jl:11
 [19] run_module_init(mod::Module, i::Int64)
    @ Base ./loading.jl:1419
 [20] register_restored_modules(sv::Core.SimpleVector, pkg::Base.PkgId, path::String)
    @ Base ./loading.jl:1407
 [21] _include_from_serialized(pkg::Base.PkgId, path::String, ocachepath::String, depmods::Vector{Any}, ignore_native::Nothing; register::Bool)
    @ Base ./loading.jl:1295
 [22] _include_from_serialized (repeats 2 times)
    @ ./loading.jl:1246 [inlined]
 [23] _require_search_from_serialized(pkg::Base.PkgId, sourcepath::String, build_id::UInt128, stalecheck::Bool; reasons::Dict{String, Int64}, DEPOT_PATH::Vector{String})
    @ Base ./loading.jl:2121
 [24] __require_prelocked(pkg::Base.PkgId, env::String)
    @ Base ./loading.jl:2621
 [25] _require_prelocked(uuidkey::Base.PkgId, env::String)
    @ Base ./loading.jl:2484
 [26] macro expansion
    @ ./loading.jl:2412 [inlined]
 [27] macro expansion
    @ ./lock.jl:294 [inlined]
 [28] __require(into::Module, mod::Symbol)
    @ Base ./loading.jl:2369
 [29] #invoke_in_world#2
    @ ./essentials.jl:1091 [inlined]
 [30] invoke_in_world
    @ ./essentials.jl:1087 [inlined]
 [31] require(into::Module, mod::Symbol)
    @ Base ./loading.jl:2361
 [32] top-level scope
    @ REPL[1]:1
during initialization of module Foo