Segfault when hitting ^C on backtrace

[jakebolewski]

Steps to reproduce:

checkout the latest master version of JuliaParser
run the testshell in bin/testshell.jl
enter """ on the testshell parse line and hit ^C immediately afterwards

v0.5/JuliaParser [master●] » julia-dev bin/testshell.jl
INFO: Recompiling stale cache file /Users/jacobbolewski/.julia/lib/v0.5/AbstractTrees.ji for module AbstractTrees.
INFO: Recompiling stale cache file /Users/jacobbolewski/.julia/lib/v0.5/JuliaParser.ji for module JuliaParser.
INFO: Recompiling stale cache file /Users/jacobbolewski/.julia/lib/v0.5/Compat.ji for module Compat.
INFO: Recompiling stale cache file /Users/jacobbolewski/.julia/lib/v0.5/TerminalUI.ji for module TerminalUI.
INFO: Recompiling stale cache file /Users/jacobbolewski/.julia/lib/v0.5/Reactive.ji for module Reactive.
INFO: Recompiling stale cache file /Users/jacobbolewski/.julia/lib/v0.5/VT100.ji for module VT100.
INFO: Recompiling stale cache file /Users/jacobbolewski/.julia/lib/v0.5/Colors.ji for module Colors.
INFO: Recompiling stale cache file /Users/jacobbolewski/.julia/lib/v0.5/FixedPointNumbers.ji for module FixedPointNumbers.
INFO: Recompiling stale cache file /Users/jacobbolewski/.julia/lib/v0.5/ColorTypes.ji for module ColorTypes.
INFO: Recompiling stale cache file /Users/jacobbolewski/.julia/lib/v0.5/Reexport.ji for module Reexport.
parse > """
^C
signal (2): Interrupt: 2
while loading /Users/jacobbolewski/.julia/v0.5/JuliaParser/bin/testshell.jl, in expression starting on line 115
_ZNK4llvm6Module13getModuleFlagENS_9StringRefE at /Users/jacobbolewski/Julia/julia-dev/usr/lib//libLLVM-3.7.dylib (unknown line)
jl_setup_module at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:896
emit_function at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:4018
jl_compile_linfo at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:809
emit_invoke at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:2688 [inlined]
emit_expr at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:3166
emit_assignment at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:2927 [inlined]
emit_expr at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:3189
emit_stmtpos at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:3068
emit_function at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:4731
jl_compile_linfo at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:809
emit_invoke at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:2688 [inlined]
emit_expr at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:3166
emit_call at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:2754
emit_expr at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:3176
emit_call at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:2754
emit_expr at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:3176
emit_assignment at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:2927 [inlined]
emit_expr at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:3189
emit_stmtpos at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:3068
emit_function at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:4731
jl_compile_linfo at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:809
emit_invoke at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:2688 [inlined]
emit_expr at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:3166
emit_function at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:4695
jl_compile_linfo at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:809
emit_invoke at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:2688 [inlined]
emit_expr at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:3166
emit_assignment at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:2927 [inlined]
emit_expr at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:3189
emit_stmtpos at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:3068
emit_function at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:4731
jl_compile_linfo at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:809
emit_invoke at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:2688 [inlined]
emit_expr at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:3166
emit_assignment at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:2981 [inlined]
emit_expr at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:3189
emit_stmtpos at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:3068
emit_function at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:4731
jl_compile_linfo at /Users/jacobbolewski/Julia/julia-dev/src/codegen.cpp:809
jl_compile_for_dispatch at /Users/jacobbolewski/Julia/julia-dev/src/gf.c:1311
jl_call_method_internal at /Users/jacobbolewski/Julia/julia-dev/src/./julia_internal.h:173 [inlined]
jl_apply_generic at /Users/jacobbolewski/Julia/julia-dev/src/gf.c:1930
#parse at ./<missing>:0
parse at /Users/jacobbolewski/.julia/v0.5/JuliaParser/src/parser.jl:2154
jl_call_method_internal at /Users/jacobbolewski/Julia/julia-dev/src/./julia_internal.h:178 [inlined]
jl_apply_generic at /Users/jacobbolewski/Julia/julia-dev/src/gf.c:1930
do_call at /Users/jacobbolewski/Julia/julia-dev/src/interpreter.c:66
eval at /Users/jacobbolewski/Julia/julia-dev/src/interpreter.c:190
jl_toplevel_eval_flex at /Users/jacobbolewski/Julia/julia-dev/src/toplevel.c:558
jl_toplevel_eval_in_warn at /Users/jacobbolewski/Julia/julia-dev/src/builtins.c:576
eval at ./boot.jl:234
jl_call_method_internal at /Users/jacobbolewski/Julia/julia-dev/src/./julia_internal.h:178 [inlined]
jl_apply_generic at /Users/jacobbolewski/Julia/julia-dev/src/gf.c:1930
#7 at /Users/jacobbolewski/.julia/v0.5/JuliaParser/bin/testshell.jl:86
jl_call_method_internal at /Users/jacobbolewski/Julia/julia-dev/src/./julia_internal.h:178 [inlined]
jl_apply_generic at /Users/jacobbolewski/Julia/julia-dev/src/gf.c:1930
run_interface at ./LineEdit.jl:1570
RunShell at /Users/jacobbolewski/.julia/v0.5/JuliaParser/bin/testshell.jl:113
jl_call_method_internal at /Users/jacobbolewski/Julia/julia-dev/src/./julia_internal.h:178 [inlined]
jl_apply_generic at /Users/jacobbolewski/Julia/julia-dev/src/gf.c:1930
do_call at /Users/jacobbolewski/Julia/julia-dev/src/interpreter.c:66
eval at /Users/jacobbolewski/Julia/julia-dev/src/interpreter.c:190
jl_toplevel_eval_flex at /Users/jacobbolewski/Julia/julia-dev/src/toplevel.c:558
jl_parse_eval_all at /Users/jacobbolewski/Julia/julia-dev/src/ast.c:717
jl_load at /Users/jacobbolewski/Julia/julia-dev/src/toplevel.c:596 [inlined]
jl_load_ at /Users/jacobbolewski/Julia/julia-dev/src/toplevel.c:605
include_from_node1 at ./loading.jl:426
jl_call_method_internal at /Users/jacobbolewski/Julia/julia-dev/src/./julia_internal.h:178 [inlined]
jl_apply_generic at /Users/jacobbolewski/Julia/julia-dev/src/gf.c:1930
process_options at ./client.jl:262
_start at ./client.jl:318
jl_call_method_internal at /Users/jacobbolewski/Julia/julia-dev/src/./julia_internal.h:178 [inlined]
jl_apply_generic at /Users/jacobbolewski/Julia/julia-dev/src/gf.c:1930
true_main at /Users/jacobbolewski/Julia/julia-dev/usr/bin/julia (unknown line)
main at /Users/jacobbolewski/Julia/julia-dev/usr/bin/julia (unknown line)
unknown function (ip: 0xffffffffffffffff)
Allocations: 2503100 (Pool: 2501372; Big: 1728); GC: 2
[1]    4323 segmentation fault  /Users/jacobbolewski/Julia/julia-dev/usr/bin/julia bin/testshell.jl

[yuyichao]

Dup of #17706

[jakebolewski]

No, I still get a segfault even with the latest master. I've updated the original backtrace in the issue now that I have rebuilt julia.

julia> versioninfo()
Julia Version 0.5.0-rc0+113
Commit fc3cbc9 (2016-08-01 20:53 UTC)
Platform Info:
  System: Darwin (x86_64-apple-darwin15.6.0)
  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 (ORCJIT, haswell)

[yuyichao]

No, I still get a segfault even with the latest master

So? #17706 is still open.

[jakebolewski]

@yuyichao from my reading of that issue, does this mean that all custom REPL modes have to add the appropriate sigatomic_begin(), sigatomic_end() statements? If that is the case feel free to close.

[yuyichao]

There's a few issues here and the segfault cannot be reliably fixed even when #17706 is closed.

1. Any code that don't want to be interrupted should be wrapped in disable_sigint and use reenable_sigint on the part that can handle InterruptException. Note that sigatomic_begin and sigatomic_end are internal APIs and their semantics can change at any time. This usually includes the error handling part of REPL.
2. Any code that want to handle InterruptException instead of existing asynchronously should ccall jl_exit_on_sigint(0). This is done in the normal REPL mode.
3. Make exit_on_sigint work again #17727 makes the exit less-segfaulty but there's no way this can be guaranteed. In this particular case, it spends a lot of time in LLVM and the exit is almost certainly going to segfault. One option is to always use _exit to exit on SIGINT, I'm not sure which one is better (segfault sometimes but does cleanup otherwise, or never segfault and never does cleanup).

[jakebolewski]

Thanks, those bullet points are a helpful synthesis of that thread. Maybe you could copy and paste those to the devdocs so they don't get lost in a morass of issue comments?

Sorry for the noise, I have not been keeping up with issues at all.