You are right. That's why outputs are sent to /dev/null in my tests.
If you are not redirecting to a file but letting it display to the terminal
then a big variable is what GUI terminal emulator you are using - XTerm,
rxvt-unicode, st, etc. I think that could create a lot of varying numbers..why
it may even depend on if you use TrueType fonts or cheaper to
But OP is not going to divert the output into `/dev/null`. In a Linux terminal
you don't really gain much benefits from avoiding flushing because it will
flush on a newline regardless.
$ time cat bigfile.txt | ./mine ; cat -n mine.nim
# ...
real0m3.707s
user
All my tests were done by redirecting stdout to /dev/null, so the performance
of terminal doesn't matter.
I was under the impression that Linux terminals usually flush on newlines
regardless. There's a chance that the main performance benefit you are gaining
is not from splitting the strings and using the split iter instead. I could be
wrong.
You could also concatenate all entries to a string variable and then do a
single writeLine to avoid I/O traffic -- a classic optimization technique.
Locking can indeed slowdown output as can exception handling and is unnecessary
for single-threaded output and the exceptions may be unhelpful if there is
nothing you can do on out of space errors. If you are on Linux/glibc then you
can also just use `fwrite_unlocked` directly as in
See updated code above
@krtekz Awesome! Also make sure you share your optimized final code here for
anyone who ends up on this thread in future :)
Also try `--gc:arc --panics:on`
Just found out something people haven't mentioned yet (or I missed it?).
According to
[https://nim-lang.org/docs/system.html](https://nim-lang.org/docs/system.html)
`echo` is equivalent to a `writeLine` and a `flushFile`, so each time I call
`echo` it flushes the output, which is not
In Rust, sometimes the biggest performance overhead is repeated locking of
stdout. To avoid it, one would lock the stdout before the loop. I wonder Nim
requires locking as well.
{
let mut out = File::new("test.out");
let mut buf = BufWriter::new(out);
let
This comes up a lot. Here are a couple recent ones:
[https://forum.nim-lang.org/t/4738](https://forum.nim-lang.org/t/4738) and
[https://forum.nim-lang.org/t/5103](https://forum.nim-lang.org/t/5103).
Thanks a lot! Total newbie here
Your code is slow for several reasons:
1\. You should wrap your code in a proc, otherwise all variables are globals
and globals are much harder to optimize, in particular they have the same
lifetime as your program so you can't reuse their memory
2\. `split` in each loop, you are allocating 1
With `-d:danger`, it improves a bit but still much slower than the Python
version.
Nim: 2.65s, Python: 1.26s
Compile with `-d:danger`.
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