On Wednesday, 21 July 2021 at 22:51:38 UTC, hanabi1224 wrote:
Hi, I'm new to D lang and encounter some performance issues
with fiber, not sure if there's something obviously wrong with
my code.
I took a quick look, and the first problem I saw was that you
were using `spawnLinked` but not replacing the scheduler.
`std.concurrency` uses a global `scheduler` variable to do its
job.
Hence doing:
```diff
- auto scheduler = new FiberScheduler();
+ scheduler = new FiberScheduler();
```
Will ensure that `spawnLinked` works as expected.
There are a few other things to consider, w.r.t. fibers:
- Our Fibers are 4 pages (on Linux) by default;
- We have an extra guard page, because we are a native language,
so we can't do the same trick as Go to auto-grow the stack;
- Spawning fibers *is* expensive and other languages reuse fibers
(Yes, Go recycle them);
The `FiberScheduler` implementation is unfortunately pretty bad:
it [does not re-use
fibers](https://github.com/dlang/phobos/blob/b48cca57e8ad2dc56872499836bfa1e70e390abb/std/concurrency.d#L1578-L1599). I believe this is the core of the issue.
