Nested anonymous functions not propagating to workers #15451
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ivirshup opened this Issue on Mar 10 · 3 comments
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parallel
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0.5.0
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@JeffBezanson JeffBezanson
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@ivirshup
@amitmurthy
@JeffBezanson
@jrevels
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@ivirshup
ivirshup commented on Mar 10

Hi,

I think I've found a bug? Nested anonymous function aren't propagating to workers with @everywhere:

julia> addprocs(1)
1-element Array{Int64,1}:
 2

julia> @everywhere f = (x->(y->y+1)(x) + 1)

julia> remotecall_fetch(f, 2, 1)
ERROR: On worker 2:
UndefVarError: 6#8 not defined
 in #5 at ./none:1
 in run_work_thunk at ./multi.jl:722
 [inlined code] from ./multi.jl:1018
 in #253 at ./task.jl:59
 in remotecall_fetch(::Any, ::Base.Worker, ::Int64, ::Vararg{Int64}) at ./multi.jl:808
 in remotecall_fetch(::Any, ::Int64, ::Int64, ::Vararg{Int64}) at ./multi.jl:811
 in eval(::Module, ::Any) at ./boot.jl:267

julia> versioninfo()
Julia Version 0.5.0-dev+3050
Commit c96f322 (2016-03-08 04:08 UTC)
Platform Info:
  System: Darwin (x86_64-apple-darwin15.3.0)
  CPU: Intel(R) Core(TM) i7-4870HQ CPU @ 2.50GHz
  WORD_SIZE: 64
  BLAS: libopenblas (USE64BITINT DYNAMIC_ARCH NO_AFFINITY Haswell)
  LAPACK: libopenblas64_
  LIBM: libopenlibm
  LLVM: libLLVM-3.7.1

Update:

I've found a more general example:

julia> addprocs(1)
1-element Array{Int64,1}:
 2

julia> remotecall_fetch((x->(y->y)(x)), 2, 1)
ERROR: On worker 2:
UndefVarError: 2#4 not defined
 in #1 at ./none:1
 in run_work_thunk at ./multi.jl:744
 [inlined code] from ./multi.jl:1040
 in #255 at ./task.jl:59
 in remotecall_fetch(::Any, ::Base.Worker, ::Int64, ::Vararg{Int64}) at ./multi.jl:830
 in remotecall_fetch(::Any, ::Int64, ::Int64, ::Vararg{Int64}) at ./multi.jl:833
 in eval(::Module, ::Any) at ./boot.jl:267

@ivirshup ivirshup changed the title from Nested anonymous functions not propagating with @everywhere to Nested anonymous functions not propagating to workers on Mar 11
@jrevels jrevels added the parallel label on Mar 11
@amitmurthy
The Julia Language member
amitmurthy commented on Mar 13

The following work:

julia> @everywhere println(f(1))
3
    From worker 2:  3
    From worker 3:  3

julia> remotecall_fetch(x->f(1), 2, 1)
3

It appears that f is indeed defined on all workers. In the case of remotecall_fetch(f, 2, 1) while one would expect only the symbol and module to be serialized, it is actually serializing the locally defined function.

cc: @JeffBezanson
This was referenced on Mar 16
Open
Serialize/Deserialize segfault #14497
Closed
Unrelated module wrapped in closure with --inline=no only #15766
@ivirshup
ivirshup commented on Apr 27 • edited

Came across another (probably more common) case:

pmap([rand(2) for i in 1:2]) do x
    map(y->typeof(y), x)
end

This generates a pretty long error report so I've put an example of running it here.

edit: corrected code.
@amitmurthy amitmurthy added this to the 0.5.0 milestone on Apr 28
@JeffBezanson JeffBezanson was assigned by tkelman on May 5
@JeffBezanson JeffBezanson added bug regression labels on May 13
@yuyichao yuyichao referenced this issue on May 16
Closed
Using pmap with multiple anon functions as arguments gives error #16387
@JeffBezanson
The Julia Language member
JeffBezanson commented on May 19

The issue here is that nested functions now generate multiple top-level functions. So the immediate function you're trying to send refers to globals in Main that are not being sent.

I think the right solution is to look through the IR for the function when it's serialized, and send over all its dependencies. This could also potentially let us remove the localize_vars hack. We can also keep track of which items from Main we've sent to which processors and avoid re-sending, which would be a helpful optimization.
@JeffBezanson JeffBezanson added a commit that referenced this issue on May 23
	@JeffBezanson 	fix #15451, serialization of nested functions 			43fdd41
@tkelman tkelman added a commit that referenced this issue on May 23
	@JeffBezanson 	fix #15451, serialization of nested functions 			0d75c1d
@tkelman tkelman added a commit that referenced this issue on May 24
	@JeffBezanson 	fix #15451, serialization of nested functions 			7b08e9b
@JeffBezanson JeffBezanson added a commit that closed this issue on May 24
	@JeffBezanson 	fix #15451, serialization of nested functions (#16535) 			3bed78c
@JeffBezanson JeffBezanson closed this in 3bed78c on May 24
@amitmurthy amitmurthy referenced this issue 6 days ago
Open
Handle global references and remove localize_vars while serializing to other workers. #19000