Do not print stacktrace when ctrl-c hit

[ViralBShah]

It would be nice to disable this stacktrace when one hits ctrl-c on a running Julia program and perhaps have an environment variable to enable seeing it:

➜  ~ julia -e "for i in 1:10^9; rand(); end"
^C^C^Cfatal: error thrown and no exception handler available.
InterruptException()
_jl_mutex_unlock at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-honeycrisp-HL2F7YQ3XH.0/build/default-honeycrisp-HL2F7YQ3XH-0/julialang/julia-release-1-dot-11/src/threading.c:969
jl_mutex_unlock at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-honeycrisp-HL2F7YQ3XH.0/build/default-honeycrisp-HL2F7YQ3XH-0/julialang/julia-release-1-dot-11/src/./julia_locks.h:80 [inlined]
jl_generate_fptr_impl at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-honeycrisp-HL2F7YQ3XH.0/build/default-honeycrisp-HL2F7YQ3XH-0/julialang/julia-release-1-dot-11/src/jitlayers.cpp:545
jl_compile_method_internal at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-honeycrisp-HL2F7YQ3XH.0/build/default-honeycrisp-HL2F7YQ3XH-0/julialang/julia-release-1-dot-11/src/gf.c:2536
_jl_invoke at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-honeycrisp-HL2F7YQ3XH.0/build/default-honeycrisp-HL2F7YQ3XH-0/julialang/julia-release-1-dot-11/src/gf.c:2940 [inlined]
ijl_apply_generic at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-honeycrisp-HL2F7YQ3XH.0/build/default-honeycrisp-HL2F7YQ3XH-0/julialang/julia-release-1-dot-11/src/gf.c:3125
display_error at ./client.jl:120
jfptr_display_error_73517.1 at /Users/viral/.julia/juliaup/julia-1.11.5+0.aarch64.apple.darwin14/lib/julia/sys.dylib (unknown line)
jl_apply at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-honeycrisp-HL2F7YQ3XH.0/build/default-honeycrisp-HL2F7YQ3XH-0/julialang/julia-release-1-dot-11/src/./julia.h:2157 [inlined]
jl_f__call_latest at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-honeycrisp-HL2F7YQ3XH.0/build/default-honeycrisp-HL2F7YQ3XH-0/julialang/julia-release-1-dot-11/src/builtins.c:875
#invokelatest#2 at ./essentials.jl:1055 [inlined]
invokelatest at ./essentials.jl:1052 [inlined]
_start at ./client.jl:547
jfptr__start_73721.1 at /Users/viral/.julia/juliaup/julia-1.11.5+0.aarch64.apple.darwin14/lib/julia/sys.dylib (unknown line)
jl_apply at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-honeycrisp-HL2F7YQ3XH.0/build/default-honeycrisp-HL2F7YQ3XH-0/julialang/julia-release-1-dot-11/src/./julia.h:2157 [inlined]
true_main at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-honeycrisp-HL2F7YQ3XH.0/build/default-honeycrisp-HL2F7YQ3XH-0/julialang/julia-release-1-dot-11/src/jlapi.c:900
jl_repl_entrypoint at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-honeycrisp-HL2F7YQ3XH.0/build/default-honeycrisp-HL2F7YQ3XH-0/julialang/julia-release-1-dot-11/src/jlapi.c:1059

[giordano]

That's very useful for knowing where a program is stuck, and you may not always have the luxury of going back in time to set the environment variable.

[ViralBShah]

I know, but 99% of the time it is an annoyance than a help.

[JamesWrigley]

Semi-relevant PR to control interrupt handling: #49541

[fingolfin]

I know, but 99% of the time it is an annoyance than a help.

Citation needed?

If we are making up numbers, for me it the stacktrace is useful in 70% of all cases...

That said, if there is an env variable or other way to enable this permanently, then I could just put this into my config and be fine :-)

[ViralBShah]

Users on unix-like systems commonly use ctrl-c as a way to kill a running program, and it feels odd to me as a user to see a stack trace. When I kill many other applications on linux, I don't usually get a stacktrace - and we often print many pages.

I'm not thinking in the shoes of a developer here, but an end user, who may not even know what Julia is. They may be running a juliac compiled binary for example.

We could also start out with having an opt-out mechanism initially, and then change the default behaviour to make it opt-in in a future release.

[mgkuhn]

On Unix you press Ctrl-C (SIGINT) to interrupt a process without debug output, and you use Ctrl-\ (SIGQUIT) if you do want debug output (i.e., a core dump) in addition. Perhaps follow that convention in Julia as well and output the stack trace only after Ctrl-\ (SIGQUIT) but not after Ctrl-C (SIGINT)?

Similarly for the kill command: at the moment, both kill (SIGTERM) and kill -QUIT (SIGQUIT) cause Julia to output a stack trace. Perhaps only the latter should?

Termination signals

[ViralBShah]

That would be perfect!