Sets test failure: !(isequal(s.dict.keys,k))

[tkelman]

Seen this in a few PR's, and now a master build: https://travis-ci.org/JuliaLang/julia/jobs/68599318 (osx)

exception on 4: ERROR: LoadError: test failed: !(isequal(s.dict.keys,k))
 in expression: !(isequal(s.dict.keys,k))
 in error at /private/tmp/julia/lib/julia/sys.dylib
 in default_handler at test.jl:29
 in do_test at test.jl:52
 in include at /private/tmp/julia/lib/julia/sys.dylib
 in runtests at /private/tmp/julia/share/julia/test/testdefs.jl:197
 in anonymous at multi.jl:837
 in run_work_thunk at multi.jl:590
 in anonymous at task.jl:837
while loading /private/tmp/julia/share/julia/test/sets.jl, in expression starting on line 95
    From worker 2:       * replutil             in  19.95 seconds
    From worker 5:       * subarray             in 343.62 seconds
    From worker 3:       * ranges               in  80.66 seconds
ERROR: LoadError: LoadError: test failed: !(isequal(s.dict.keys,k))
 in expression: !(isequal(s.dict.keys,k))
 in anonymous at task.jl:1403
while loading /private/tmp/julia/share/julia/test/sets.jl, in expression starting on line 95
while loading /private/tmp/julia/share/julia/test/runtests.jl, in expression starting on line 5
    From worker 4:       * sets                

Can anyone reproduce locally?

[yuyichao]

The failing test seems to be the newly added rehash! test. From dict.jl, it seems that there's not really a grantee that rehash! should create a new key object.

[yuyichao]

And from the comment, this behavior is GC sensitive which can probably explain that it doesn't happen everytime.

[yuyichao]

Ref #11795

[yuyichao]

Actually that line just cause a retry so it should not be a problem?

[yuyichao]

The issue seems to be that the rehash doesn't really have to do anything (it basically just create another hash table) However, since it doesn't initialize the not used elements in the key table (and it doesn't need to do that), the key array can be equal or not depending on whatever was in the array initiailly.

Best shown like this.

julia> function t()
       s = Set(1:5)
       k = s.dict.keys
       Base.rehash!(s)
       s.dict.keys, k
       end
t (generic function with 1 method)

julia> t()
([0,4,0,0,0,2,3,0,140728686160976,0,0,0,5,0,0,1],[0,4,0,0,0,2,3,0,140728687306304,0,0,0,5,0,0,1])

julia> t()
([140728687306016,4,0,140728687305952,0,2,3,0,0,0,0,0,5,140728687306080,0,1],[140728687304960,4,0,140728687305120,0,2,3,0,0,0,140728687304416,140728687304448,5,140728687305296,0,1])

[yuyichao]

IMHO, the best way to test this might be sth like this.

julia> function t()
       s = Set(["a", "b", "c"])
       Base.rehash!(s)
       k = s.dict.keys
       Base.rehash!(s)
       s.dict.keys, k
       end
t (generic function with 1 method)

julia> t()
(ASCIIString[#undef,#undef,#undef,"c",#undef,#undef,#undef,#undef,"b",#undef,#undef,#undef,#undef,"a",#undef,#undef],ASCIIString[#undef,#undef,#undef,"c",#undef,#undef,#undef,#undef,"b",#undef,#undef,#undef,#undef,"a",#undef,#undef])

julia> t()
(ASCIIString[#undef,#undef,#undef,"c",#undef,#undef,#undef,#undef,"b",#undef,#undef,#undef,#undef,"a",#undef,#undef],ASCIIString[#undef,#undef,#undef,"c",#undef,#undef,#undef,#undef,"b",#undef,#undef,#undef,#undef,"a",#undef,#undef])

P.S. how do we compare two arrays with embeded #undef ?

[yuyichao]

Implemented #11892