slow printing in terminals

[StefanKarpinski]

https://discourse.julialang.org/t/why-is-printing-to-a-terminal-slow/42987

Requires a terminal that can render output fast (seems like iTerm2 doesn't) to demonstrate.

[StefanKarpinski]

Could be an issue of I/O locking.

[paulmelis]

I guess this part from my post in the thread above also belongs here:

paulm@cmstorm 09:38:/data/examples/julia$ cat print_integers.py 
for i in range(1, 10000001):
    print(i)

paulm@cmstorm 09:38:/data/examples/julia$ cat print_integers.jl 
for i in 1 : 10000000
    println(i)
end

paulm@cmstorm 09:38:/data/examples/julia$ time python print_integers.py | less
<press ">" followed by "q" and wait for script to finish>

real	0m3.474s
user	0m3.723s
sys	0m0.080s

paulm@cmstorm 09:38:/data/examples/julia$ time julia -O3 print_integers.jl | less
<press ">" followed by "q" and wait for script to finish>

real	0m53.254s
user	0m39.575s
sys	0m47.758s

paulm@cmstorm 09:43:/data/examples/julia$ strace -c -o out.python python print_integers.py | less
<press ">" followed by "q" and wait for script to finish>

paulm@cmstorm 09:43:/data/examples/julia$ strace -c -o out.julia julia -O3 print_integers.jl | less
<press ">" followed by "q" and wait for script to finish>

paulm@cmstorm 09:54:/data/examples/julia$ grep write out.python 
 18.68    0.001243           0      9626           write
paulm@cmstorm 09:54:/data/examples/julia$ grep wait out.python 
paulm@cmstorm 09:54:/data/examples/julia$

paulm@cmstorm 09:54:/data/examples/julia$ grep write out.julia 
 41.49   49.752976           2  20000003           write
  0.00    0.000010           0        13           pwrite64
paulm@cmstorm 09:55:/data/examples/julia$ grep wait out.julia 
 58.49   70.127743           1  40000001           epoll_pwait