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Too big Unions segfault #27101

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Liozou opened this issue May 14, 2018 · 3 comments
Open

Too big Unions segfault #27101

Liozou opened this issue May 14, 2018 · 3 comments
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domain:types and dispatch Types, subtyping and method dispatch

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@Liozou
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Liozou commented May 14, 2018 •
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Julia does not seem to be able to handle a Union of strictly more than 3265 types.

First, it segfaults when trying to print it:

julia> n = 3266
3266

julia> for i in 1:n
           eval(Meta.parse("struct T$i end")) # Creating the types
       end

julia> collection = (eval(Meta.parse("T$i")) for i in 1:n)
Base.Generator{UnitRange{Int64},getfield(Main, Symbol("##3#4"))}(getfield(Main, Symbol("##3#4"))(), 1:3266)

julia> Union{collection...}

signal (11): Segmentation fault
in expression starting at no file:0
unknown function (ip: 0x7f8626f4b319)
memset at /usr/include/x86_64-linux-gnu/bits/string3.h:90 [inlined]
restore_env at /home/liozou/julia/src/subtype.c:172 [inlined]
exists_subtype at /home/liozou/julia/src/subtype.c:1013 [inlined]
forall_exists_subtype at /home/liozou/julia/src/subtype.c:1039
jl_subtype_env at /home/liozou/julia/src/subtype.c:1094
jl_types_equal at /home/liozou/julia/src/subtype.c:1119
typekey_eq at /home/liozou/julia/src/jltypes.c:664 [inlined]
lookup_type_idx at /home/liozou/julia/src/jltypes.c:720
lookup_type at /home/liozou/julia/src/jltypes.c:731 [inlined]
inst_datatype_inner at /home/liozou/julia/src/jltypes.c:1106
inst_datatype_env at /home/liozou/julia/src/jltypes.c:1309 [inlined]
inst_datatype_env at /home/liozou/julia/src/jltypes.c:1313
inst_datatype at /home/liozou/julia/src/jltypes.c:1319 [inlined]
inst_type_w_ at /home/liozou/julia/src/jltypes.c:1510
jl_instantiate_unionall at /home/liozou/julia/src/jltypes.c:940
arg_type_tuple at /home/liozou/julia/src/gf.c:1639
jl_lookup_generic_ at /home/liozou/julia/src/gf.c:2144 [inlined]
jl_apply_generic at /home/liozou/julia/src/gf.c:2175
inner at ./essentials.jl:662
jl_fptr_trampoline at /home/liozou/julia/src/gf.c:1849
jl_apply_generic at /home/liozou/julia/src/gf.c:2178
jl_apply at /home/liozou/julia/src/julia.h:1541 [inlined]
jl_f__apply at /home/liozou/julia/src/builtins.c:554
jl_f__apply_latest at /home/liozou/julia/src/builtins.c:592
#invokelatest#3 at ./essentials.jl:663 [inlined]
invokelatest at ./essentials.jl:662 [inlined]
print_response at /home/liozou/julia/usr/share/julia/stdlib/v0.7/REPL/src/REPL.jl:151
jfptr_print_response_17986 at /home/liozou/julia/usr/lib/julia/sys.so (unknown line)
jl_apply_generic at /home/liozou/julia/src/gf.c:2178
print_response at /home/liozou/julia/usr/share/julia/stdlib/v0.7/REPL/src/REPL.jl:137
jfptr_print_response_17982 at /home/liozou/julia/usr/lib/julia/sys.so (unknown line)
jl_apply_generic at /home/liozou/julia/src/gf.c:2178
do_respond at /home/liozou/julia/usr/share/julia/stdlib/v0.7/REPL/src/REPL.jl:705
unknown function (ip: 0x7f8614343982)
jl_apply_generic at /home/liozou/julia/src/gf.c:2178
do_call at /home/liozou/julia/src/interpreter.c:324
eval_value at /home/liozou/julia/src/interpreter.c:416
eval_body at /home/liozou/julia/src/interpreter.c:538
jl_interpret_toplevel_thunk_callback at /home/liozou/julia/src/interpreter.c:798
unknown function (ip: 0xfffffffffffffffe)
unknown function (ip: 0x7f86175bdecf)
unknown function (ip: 0xffffffffffffffff)
jl_interpret_toplevel_thunk at /home/liozou/julia/src/interpreter.c:807
jl_toplevel_eval_flex at /home/liozou/julia/src/toplevel.c:856
jl_toplevel_eval_in at /home/liozou/julia/src/builtins.c:624
eval at ./boot.jl:317 [inlined]
eval at /home/liozou/julia/usr/share/julia/stdlib/v0.7/REPL/src/LineEdit.jl:3
jl_apply_generic at /home/liozou/julia/src/gf.c:2178
run_interface at /home/liozou/julia/usr/share/julia/stdlib/v0.7/REPL/src/LineEdit.jl:2213
jl_apply_generic at /home/liozou/julia/src/gf.c:2178
run_frontend at /home/liozou/julia/usr/share/julia/stdlib/v0.7/REPL/src/REPL.jl:1025
run_repl at /home/liozou/julia/usr/share/julia/stdlib/v0.7/REPL/src/REPL.jl:187
jl_fptr_trampoline at /home/liozou/julia/src/gf.c:1849
jl_apply_generic at /home/liozou/julia/src/gf.c:2178
#680 at ./client.jl:416
inner at ./essentials.jl:662
jl_fptr_trampoline at /home/liozou/julia/src/gf.c:1849
jl_apply_generic at /home/liozou/julia/src/gf.c:2178
jl_apply at /home/liozou/julia/src/julia.h:1541 [inlined]
jl_f__apply at /home/liozou/julia/src/builtins.c:554
jl_f__apply_latest at /home/liozou/julia/src/builtins.c:592
#invokelatest#3 at ./essentials.jl:663 [inlined]
invokelatest at ./essentials.jl:662 [inlined]
run_main_repl at ./client.jl:400
exec_options at ./client.jl:338
_start at ./client.jl:457
jl_apply_generic at /home/liozou/julia/src/gf.c:2178
unknown function (ip: 0x401c90)
unknown function (ip: 0x40145c)
__libc_start_main at /build/glibc-Cl5G7W/glibc-2.23/csu/../csu/libc-start.c:291
unknown function (ip: 0x401508)
Allocations: 2448638 (Pool: 2447464; Big: 1174); GC: 5
Segmentation fault (core dumped)

Note that the error does not come from splatting nor from the creation of the Union itself, since adding a ; at the end of the line removes the segfault.

Second issue, it segfaults on dispatch:

julia> n = 3266
3266

julia> for i in 1:n
           eval(Meta.parse("struct T$i end"))
       end

julia> collection = (eval(Meta.parse("T$i")) for i in 1:n)
Base.Generator{UnitRange{Int64},getfield(Main, Symbol("##3#4"))}(getfield(Main, Symbol("##3#4"))(), 1:3265)

julia> T = Union{collection...}; # no segfault here while not printing T

julia> function foo(::T) end
foo (generic function with 1 method)

julia> foo(42)

signal (11): Segmentation fault
in expression starting at no file:0
unknown function (ip: 0x7f8a13cbc319)
memset at /usr/include/x86_64-linux-gnu/bits/string3.h:90 [inlined]
restore_env at /home/liozou/julia/src/subtype.c:172 [inlined]
exists_subtype at /home/liozou/julia/src/subtype.c:1013 [inlined]
forall_exists_subtype at /home/liozou/julia/src/subtype.c:1039
jl_subtype_env at /home/liozou/julia/src/subtype.c:1094
subtype_tuple at /home/liozou/julia/src/subtype.c:797 [inlined]
subtype at /home/liozou/julia/src/subtype.c:930
exists_subtype at /home/liozou/julia/src/subtype.c:1011 [inlined]
forall_exists_subtype at /home/liozou/julia/src/subtype.c:1039
jl_subtype_env at /home/liozou/julia/src/subtype.c:1094
jl_subtype_matching at /home/liozou/julia/src/subtype.c:2261
jl_typemap_assoc_by_type_ at /home/liozou/julia/src/typemap.c:596
jl_mt_assoc_by_type at /home/liozou/julia/src/gf.c:1102
jl_lookup_generic_ at /home/liozou/julia/src/gf.c:2146 [inlined]
jl_apply_generic at /home/liozou/julia/src/gf.c:2175
do_call at /home/liozou/julia/src/interpreter.c:324
eval_value at /home/liozou/julia/src/interpreter.c:416
eval_body at /home/liozou/julia/src/interpreter.c:559
jl_interpret_toplevel_thunk_callback at /home/liozou/julia/src/interpreter.c:798
unknown function (ip: 0xfffffffffffffffe)
unknown function (ip: 0x7f8a041e9daf)
unknown function (ip: 0xffffffffffffffff)
jl_interpret_toplevel_thunk at /home/liozou/julia/src/interpreter.c:807
jl_toplevel_eval_flex at /home/liozou/julia/src/toplevel.c:856
jl_toplevel_eval_in at /home/liozou/julia/src/builtins.c:624
eval at ./boot.jl:317 [inlined]
eval at /home/liozou/julia/usr/share/julia/stdlib/v0.7/REPL/src/REPL.jl:5
jl_apply_generic at /home/liozou/julia/src/gf.c:2178
eval_user_input at /home/liozou/julia/usr/share/julia/stdlib/v0.7/REPL/src/REPL.jl:85
jl_apply_generic at /home/liozou/julia/src/gf.c:2178
macro expansion at /home/liozou/julia/usr/share/julia/stdlib/v0.7/REPL/src/REPL.jl:116 [inlined]
#28 at ./event.jl:92
jl_fptr_trampoline at /home/liozou/julia/src/gf.c:1849
jl_apply_generic at /home/liozou/julia/src/gf.c:2178
jl_apply at /home/liozou/julia/src/julia.h:1541 [inlined]
start_task at /home/liozou/julia/src/task.c:268
unknown function (ip: 0xffffffffffffffff)
Allocations: 2287277 (Pool: 2286198; Big: 1079); GC: 5
Segmentation fault (core dumped)

Neither of the two segfaults happens on my computer for n = 3265, but I don't know if that matters.
@quinnj
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quinnj commented May 14, 2018

Probably a dup of #22509?

@JeffBezanson
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Likely the same or similar core issue as #26065 #25388 #22123 #21191.

The printing and dispatch errors here are basically the same, since dispatch is needed to print.

@Liozou
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Liozou commented May 14, 2018

In the same context, taking n = 3265 in the last example does not segfault but throws an error on dispatch, as expected. However, even half an hour after the red ERROR: is printed, no actual error and backtrace show up, the REPL is dead frozen.

@kshyatt kshyatt added the domain:types and dispatch Types, subtyping and method dispatch label May 28, 2018
@JeffBezanson JeffBezanson mentioned this issue Sep 18, 2018
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