Julia fails to run _before_ epoch

[nico202]

Julia crashes on start when time is 0 (1970-01-01):

faketime "1970-01-01" julia

fatal: error thrown and no exception handler available.
#<null>
rec_backtrace at /tmp/guix-build-julia-1.1.1.drv-0/julia-1.1.1/src/stackwalk.c:94
record_backtrace at /tmp/guix-build-julia-1.1.1.drv-0/julia-1.1.1/src/task.c:217 [inlined]
jl_throw at /tmp/guix-build-julia-1.1.1.drv-0/julia-1.1.1/src/task.c:417
Type at ./float.jl:682 [inlined]
convert at ./number.jl:7 [inlined]
cconvert at ./essentials.jl:355 [inlined]
srand at ./libc.jl:384 [inlined]
srand at ./libc.jl:384 [inlined]
__init__ at ./sysimg.jl:489
jl_apply_generic at /tmp/guix-build-julia-1.1.1.drv-0/julia-1.1.1/src/gf.c:2197
jl_apply at /tmp/guix-build-julia-1.1.1.drv-0/julia-1.1.1/src/julia.h:1571 [inlined]
jl_module_run_initializer at /tmp/guix-build-julia-1.1.1.drv-0/julia-1.1.1/src/toplevel.c:72
_julia_init at /tmp/guix-build-julia-1.1.1.drv-0/julia-1.1.1/src/init.c:832
unknown function (ip: 0x402307)
__libc_start_main at /gnu/store/ahqgl4h89xqj695lgqvsaf6zh2nhy4pj-glibc-2.29/lib/libc.so.6 (unknown line)
unknown function (ip: 0x4023b9)
nixo@guixSD ~/git/guix-julia-dev [env]$ faketime "1970-01-01" julia
fatal: error thrown and no exception handler available.
#<null>
rec_backtrace at /tmp/guix-build-julia-1.1.1.drv-0/julia-1.1.1/src/stackwalk.c:94
record_backtrace at /tmp/guix-build-julia-1.1.1.drv-0/julia-1.1.1/src/task.c:217 [inlined]
jl_throw at /tmp/guix-build-julia-1.1.1.drv-0/julia-1.1.1/src/task.c:417
Type at ./float.jl:682 [inlined]
convert at ./number.jl:7 [inlined]
cconvert at ./essentials.jl:355 [inlined]
srand at ./libc.jl:384 [inlined]
srand at ./libc.jl:384 [inlined]
__init__ at ./sysimg.jl:489
jl_apply_generic at /tmp/guix-build-julia-1.1.1.drv-0/julia-1.1.1/src/gf.c:2197
jl_apply at /tmp/guix-build-julia-1.1.1.drv-0/julia-1.1.1/src/julia.h:1571 [inlined]
jl_module_run_initializer at /tmp/guix-build-julia-1.1.1.drv-0/julia-1.1.1/src/toplevel.c:72
_julia_init at /tmp/guix-build-julia-1.1.1.drv-0/julia-1.1.1/src/init.c:832
unknown function (ip: 0x402307)
__libc_start_main at /gnu/store/ahqgl4h89xqj695lgqvsaf6zh2nhy4pj-glibc-2.29/lib/libc.so.6 (unknown line)
unknown function (ip: 0x4023b9)

(faketime 1970-01-02) does work

versioninfo()
Commit 55e36cc308 (2019-05-16 04:10 UTC)
Platform Info:
  OS: Linux (x86_64-unknown-linux-gnu)
  CPU: Intel(R) Core(TM)2 CPU         P8600  @ 2.40GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-6.0.1 (ORCJIT, penryn)
Environment:

[nico202]

Maybe there's a locale problem?

faketime -f '1970-01-01 01:00:00' julia -E 'time()'
0.0

[nico202]

I can confirm it's the locale. I'll close this in a few hours if nobody think that the error should be addressed

[StefanKarpinski]

Julia should crash even if the locale is set to something weird. Can you give more reproduction details?

[nico202]

(with locale I meant time zone, date: Mon 09 Dec 2019 05:21:45 PM CET)

faketime -f '1970-01-01 00:00:00' julia -E 'time()' -> error in the OP
faketime -f '1970-01-01 00:59:00' julia -E 'time()' -> error in the OP
faketime -f '1970-01-01 01:00:00' julia -E 'time()' -> 0.0
TZ="London" faketime -f '1970-01-01 00:00:00' julia -E 'time()' -> 0.0

So: julia does not like time before the epoch (negative time?).

However, date does work (NOTE: 1900)
faketime -f '1900-01-01 00:00:00' date

Mon 01 Jan 1900 12:00:00 AM CET

[nico202]

Also, it will become unusable in less than 100years from now (2106-02-07).

That means either that The 100 was lying or the bug will be fixed 🤣

[ViralBShah]

The 100 uses Julia

https://juliacomputing.com/communication/2017/09/19/julia-the-ai-language-for-next-150-years.html

[nico202]

Yep, that's why I linked it 😕

[anaveragehuman]

The issue is in libc.jl in the line:

srand(seed=floor(time())) = ccall(:srand, Cvoid, (Cuint,), seed)

Before the epoch, floor(time()) would be a negative value, but C's srand() takes an unsigned int.

[nico202]

Thanks, I did not have time to try it. Does it fix also the opposite (from date 2106-02-07 on)?

[anaveragehuman]

Yes, the opposite will also work.

$ faketime "10000-01-01 00:00:00" ./julia -E 'time()'
2.5340231880103674e11