On Tuesday, 16 January 2024 at 22:15:04 UTC, Siarhei Siamashka
wrote:
On Tuesday, 16 January 2024 at 21:15:19 UTC, Renato wrote:
For the record (I already posted this on GitHub)... here's [my
current fastest
solution](https://github.com/renatoathaydes/prechelt-phone-number-encoding/blob/dlang-key-hash-incremental/src/d/src/dencoder.d) time using the same algorithm as Rust ...
[...]
... what I am really curious about is what the code I wrote is
doing wrong that causes it to run 4x slower than Rust despite
doing "the same thing"...
It's a GC allocations fest. Things like this make it slow:
```diff
{
- string digit = [digits[0]];
+ string digit = digits[0 .. 1];
words.insertBack(digit);
```
I was under the impression that `[digits[0]]` would just use a
stack allocation??
The profiler does not show any GC anymore, are you sure it's a
"GC allocations fest"???
And at the top is the associative array lookup (when profiling
the handling of the "phones_1_000_000_with_empty.txt" input
file):
```
36.85% dencoder dencoder [.] _aaInX
12.38% dencoder dencoder [.] void
Well, I know, but I did everything to make the hash "cheap" to
compute so I still don't see a way to improve it.
