NullException with procs(::Int) when using --machinefile #11230
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jaak-s opened this Issue on May 11, 2015 · 3 comments
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@jaak-s
jaak-s commented on May 11, 2015

When starting Julia with --machinefile the command procs gives NullException:

jaak@node-1-14:~$ julia --machinefile test.machinefile 
...
  | | |_| | | | (_| |  |  Version 0.4.0-dev+4603 (2015-05-02 18:25 UTC)
 _/ |\__'_|_|_|\__'_|  |  Commit 803193e* (8 days old master)
|__/                   |  x86_64-linux-gnu

julia> workers()
2-element Array{Int64,1}:
 2
 3

julia> procs(2)
ERROR: NullException()
 in == at nullable.jl:42
 in anonymous at multi.jl:261
 in filter at ./array.jl:1321
 in procs at multi.jl:261

julia> procs(3)
ERROR: NullException()
 in == at nullable.jl:42
 in anonymous at multi.jl:261
 in filter at ./array.jl:1321
 in procs at multi.jl:261

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

No problem with general parallel commands:

julia> fetch(@spawnat 3 sum(rand(10,10)))
46.096993964605204

In my setup julia is started on node1 and the machine file is

node1
node2

The problem does not happen if julia is started with julia -p 2.
@jakebolewski
The Julia Language member
jakebolewski commented on May 11, 2015

Hi @jaak-s, could you post the machinefile you are trying to use? Should be a simple fix.
@jakebolewski jakebolewski added the parallel label on May 11, 2015
@jaak-s
jaak-s commented on May 11, 2015

Machine file looks like this:

jaak@node1:~$ cat test.machinefile 
node1
node2

However, at the moment it seems any machine file will cause the same Exception, for example, I've tried:

node1
node1

or

node2

@jaak-s
jaak-s commented on May 13, 2015

Btw, this bug also affects SharedArray when julia is started with machinefile

julia> SharedArray(Float64, 10, pids=[2])
ERROR: NullException()
 in == at nullable.jl:42
 in anonymous at multi.jl:261
 in filter at ./array.jl:1346
 in procs at multi.jl:261
 in SharedArray at sharedarray.jl:43
 in SharedArray at sharedarray.jl:113

@amitmurthy amitmurthy added a commit that referenced this issue on Jun 8, 2015
	@amitmurthy 	closes #11230 			fbce5b5
@amitmurthy amitmurthy referenced this issue on Jun 8, 2015
Merged
fix NullException in procs(::Int) #11616
@amitmurthy amitmurthy closed this in #11616 on Jun 8, 2015
@tkelman tkelman added a commit to tkelman/julia that referenced this issue on Jun 8, 2015
	@amitmurthy 	closes #11230