Closed
Description
openedon Apr 3, 2018
When printing from finalizers, we're used to see errors relating to streams being closed:
julia> finalizer(x->println(x), "")
""
julia>
error in running finalizer: ArgumentError(msg="stream is closed or unusable")
With Logging, this becomes worse as certain functions called by the stdlib on the closed streams cause Julia to segfault:
julia> finalizer(x->@info(x), "")
""
julia>
signal (11): Segmentation fault
in expression starting at no file:0
uv_tty_get_winsize at /home/tbesard/Julia/julia-dev/deps/srccache/libuv-be317349252699670131395f125c3861d793ca86/src/unix/tty.c:243
displaysize at ./stream.jl:403
unknown function (ip: 0x7f7d85e45797)
jl_call_fptr_internal at /home/tbesard/Julia/julia-dev/src/julia_internal.h:383 [inlined]
jl_call_method_internal at /home/tbesard/Julia/julia-dev/src/julia_internal.h:402 [inlined]
jl_apply_generic at /home/tbesard/Julia/julia-dev/src/gf.c:2100
#handle_message#2 at /home/tbesard/Julia/julia-dev/build/release/usr/share/julia/site/v0.7/Logging/src/ConsoleLogger.jl:99
unknown function (ip: 0x7f7d85e4ccc9)
jl_call_fptr_internal at /home/tbesard/Julia/julia-dev/src/julia_internal.h:383 [inlined]
jl_call_method_internal at /home/tbesard/Julia/julia-dev/src/julia_internal.h:402 [inlined]
jl_apply_generic at /home/tbesard/Julia/julia-dev/src/gf.c:2100
jl_apply at /home/tbesard/Julia/julia-dev/src/julia.h:1529 [inlined]
jl_invoke at /home/tbesard/Julia/julia-dev/src/gf.c:55
handle_message at /home/tbesard/Julia/julia-dev/build/release/usr/share/julia/site/v0.7/Logging/src/ConsoleLogger.jl:90
unknown function (ip: 0x7f7d85e4ba41)
jl_call_fptr_internal at /home/tbesard/Julia/julia-dev/src/julia_internal.h:383 [inlined]
jl_call_method_internal at /home/tbesard/Julia/julia-dev/src/julia_internal.h:402 [inlined]
jl_apply_generic at /home/tbesard/Julia/julia-dev/src/gf.c:2100
macro expansion at ./logging.jl:314 [inlined]
#5 at ./REPL[1]:1
jl_call_fptr_internal at /home/tbesard/Julia/julia-dev/src/julia_internal.h:383 [inlined]
jl_call_method_internal at /home/tbesard/Julia/julia-dev/src/julia_internal.h:402 [inlined]
jl_apply_generic at /home/tbesard/Julia/julia-dev/src/gf.c:2100
jl_apply at /home/tbesard/Julia/julia-dev/src/julia.h:1529 [inlined]
run_finalizer at /home/tbesard/Julia/julia-dev/src/gc.c:112
jl_gc_run_finalizers_in_list at /home/tbesard/Julia/julia-dev/src/gc.c:204
run_finalizers at /home/tbesard/Julia/julia-dev/src/gc.c:240
jl_atexit_hook at /home/tbesard/Julia/julia-dev/src/init.c:260
unknown function (ip: 0xd29726c7a1)
__libc_start_main at /usr/lib/libc.so.6 (unknown line)
unknown function (ip: 0xd29726c609)
Allocations: 1186584 (Pool: 1185691; Big: 893); GC: 2
zsh: segmentation fault julia --depwarn=no --color=yes
A quick fix would be to reconfigure the global logger at exit to use raw streams, preventing the segfault and making it possible to log rich messages from finalizers:
julia> using Logging
julia> atexit(()->global_logger(Logging.ConsoleLogger(Core.stderr)))
julia> finalizer(x->@info(x), "yay")
"yay"
julia>
[ Info: yay
... but I'm not sure how that plays into the design of Logging (@c42f), or whether this is acceptable as an atexit hook.
In a related vein, this is also a very useful pattern to be able to log from @generated functions.
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