spawned processes no longer propagate modules loaded in master memory? #11209
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jiahao opened this Issue on May 8, 2015 · 2 comments
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@jiahao
@simonster
@JeffBezanson
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@jiahao
The Julia Language member
jiahao commented on May 8, 2015

This seems to be a regression from 0.3. In 0.4, a module loaded into memory before addprocs no longer gets broadcast to the spawned processes. A pmap involving a function in that module throws a "module not defined" warning, then an UndefVarError, which apparently causes the serializer to panic with an EOFError, resulting in all workers committing suicide en masse and ending in unmitigated chaos.

julia> using Color

julia> addprocs(4);

julia> pmap(identity, [RGB(rand(3)...) for i=1:100]) #pmap 100 random RGB colors
WARNING: Module Color not defined on process 3WARNING: Module Color not defined on process 4WARNING: Module Color not defined on process 5


WARNING: Module Color not defined on process 2
fatal error on fatal error on 4: 3: fatal error on 5: fatal error on 2: ERROR: UndefVarError: Color not defined
 in deserialize at serialize.jl:433
 in handle_deserialize at serialize.jl:403
 in deserialize at serialize.jl:555
 in handle_deserialize at serialize.jl:403
 in anonymous at task.jl:834
...
Worker 4 terminated.
Worker 2 terminated.ERROR (unhandled task failure): EOFError: read end of file
 in read at ./iobuffer.jl:89
 in read at stream.jl:715
 in anonymous at task.jl:819

4-element Array{Any,1}Worker 5 terminated.ERROR (unhandled task failure): EOFError: read end of file
 in yieldto at task.jl:21
 in wait at ./task.jl:309
 in wait at ./task.jl:225
 in wait_full at ./multi.jl:572
 in remotecall_fetch at multi.jl:672
 in remotecall_fetch at multi.jl:677
 in anonymous at task.jl:1392
:
...
ProcessExitedException()ERROR (unhandled task failure): EOFError: read end of file
 in yieldto at task.jl:21
 in wait at ./task.jl:309
 in wait at ./task.jl:225
 in wait_full at ./multi.jl:572
 in remotecall_fetch at multi.jl:672
 in remotecall_fetch at multi.jl:677
 in anonymous at task.jl:1392

 ProcessExitedException()
 ProcessExitedException()
 ProcessExitedException()

julia> ans
4-element Array{Any,1}:
 ProcessExitedException()
 ProcessExitedException()
 ProcessExitedException()
 ProcessExitedException()

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

On julia 0.3, the result of the pmap is the expected Array of random RGB colors:

julia> pmap(identity, [RGB(rand(3)...) for i=1:100])
100-element Array{Any,1}:
 RGB{Float64}(0.6337511173541939,0.6040774608484489,0.2725514360446333)     
 RGB{Float64}(0.3116625267416464,0.33448474093539704,0.2139489260536025)    
...

@jiahao jiahao added parallel regression labels on May 8, 2015
@simonster
The Julia Language member
simonster commented on May 10, 2015

This fails for me on 0.3 on OS X. The issue for the using/addprocs order dependency is #3674, which is still open, so I'm not sure it was ever supposed to work.
@JeffBezanson JeffBezanson removed the regression label on Jul 20, 2015
@JeffBezanson
The Julia Language member
JeffBezanson commented on Jul 20, 2015

Yes I think this is a dup of #3674.
@JeffBezanson JeffBezanson closed this on Jul 20, 2015