Julia slower than Python to sort and reverse a list of integers

jar1 · April 13, 2023, 11:38pm

I think it’s that Python buffers stdout by default and Julia doesn’t.

Println performance bug in interactive terminal (I.e. much slower than c, perl, ruby, python)

opened 10:36PM - 20 Nov 21 UTC

performance I/O

In brief: Julia println output speed seems oddly slow, or costly, in an interactive terminal compare to several other languages. The slow behavior is only occurring in an interactive terminal (tried several such as gnome-terminal, xterm, qterminal, sakura, emacs-vterm). No slowness are visible when the standard output is redirected. 1) In details (Linux Debian sid, julia 1.5.3, similar behavior on several x86_64 (Intel, AMD)) I wrote recursive Fibonacci computation with printf inside (Julia code below), in several languages for, e.g., demonstrating the synchronization in a terminal for my OS lecture. Julia computation performance is on par with C, C++, Rust, Fortran, Go, Crystal, without the println, but, with the println, Julia is much much slower (2.5 - 6.5 times slower) than even python3, perl5, ruby or node-js. Only Raku is slower but because the Raku 2021.09 computation are still very slow. If the output is redirected to /dev/null, Julia is again on par with the fastest languages. The most comparable language I tried, "crystal" (ruby compilation with LLVM), does not have the same behavior. 2) Remarks: According to /usr/bin/time ('time" package in Debian) Julia seems to spend much more time in the kernel: twice the time compare to perl or python. perf trace julia... records roughly 4M syscalls for fibo(30) compare to roughly 1M in C, perl or python, and 2M for crystal perf record/report indicates VDSO gettimeofday at the top (3%) 3) My Fibonacci code: ```julia import Printf: @printf function fibo_println(n) if n < 2 return n end val = fibo_println(n-1) + fibo_println(n-2) println(val) return val end n = 20 if length(ARGS) > 0 n = parse(Int64, ARGS[1]) end v, t = @timed fibo_println(n) @printf(stderr, "julia fibo(%d)= %lld en %lld s\n", n, v, t) ```

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Julia slower than Python to sort and reverse a list of integers

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