On Wednesday, 6 July 2016 at 11:33:53 UTC, Eugene Wissner wrote:
The only reason libev was choosen is that it is the simplest
implementation I know about. A few C files. I had an
educational purpose: I wanted to see how an event loop works on
low level. Asyncio was for me no-go, since I've not written a
lot in C++, and can only read the code a bit. So I'm not
hanging on libev. The only another implementation would be the
python event library. It is also pure C code and it was much
more cleaner written than libev on the first sight.
Your project and work is valuable on many aspects. I didn't mean
to depreciate it.
Now there are two problems with my work:
1) The first is something we all are tired to talk about:
manual memory management. I make a proof of concept and am
writing the code that is 100% marked as @nogc. It has side
effects. For example I allocate exceptions and thay should be
freed after catching - it is something, phobos doesn't do. As
said it is an experiment; I would like to see how it works.
2) Performance. The main reason I started the writing at all is
that the existing implementations seem to have only performance
as criterium. Performance is super important, but not on the
cost of design, usability and extensibility. For example in
vibe.d (and libasync) everything possible is defined as
structs, everything that would be interesting to extend is
final; and after it you go to phobos and see a "workaround".
For example Mallocator is a struct but you have to be sure, it
is an allocator. How do you force the right interface?
That is a valid point. I know it is hard to get the best
performance and optimal API design at the same time. The reason
the methods are final is to avoid the overhead of virtual method
indirection.
static if (hasMember!(Allocator, "deallocate"))
{
return impl.deallocate(b);
}
else
{
return false;
}
Somethinkg like this would be ok for C. But for a language with
interfaces, it is ugly design independent of how it performs.
Everything I say here is IMHO.
This would mean we need a new design pattern that supports both.
Except these two points I'm interested in some kind of
collective work aswell. It is very difficult as one man job. I
didn't know other people are also working on similar
implementations. Nice to know.
Are you aware of any benchmark tools in other languages that
could be used?
The benchmark tools available are mainly testing web servers. And
the exact operation pattern is not very clear. One of such
benchmark tool is wrk [https://github.com/wg/wrk] that measure
HTTP request speed. The problem is that it measure the
performance of the I/O and HTTP handling.
Here are some benchmark results:
* https://www.techempower.com/benchmarks/
* https://github.com/nanoant/WebFrameworkBenchmark
How can D be worse than Java ?
My strategy would be to split the problem. First get the async
I/O optimal. Then get HTTP handling optimal, and finally get
database interaction optimal (the optimal async I/O should help).
An investigation on the methods used by Java/undertow to get
these performances could help.
I would suggest to implement a benchmark client doing some
predefined patterns of I/O operations similar to web interactions
or the most common types of interactions. And a server
implemented in C using native system I/O operations. This server
implementation would then be our reference.
What would be measured is how much slower our different D
implementations are relative to the C reference implementation.
This will allow us to have a benchmarking test that doesn't
depend that much of the hardware.
