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by chusk3 2367 days ago
A big push in .net core 2.x and 3.x was what we call the Span-ification of the base class library and the runtime. This means there are many new APIs for dealing with slices of memory in a non-allocating manner, and this combined with memory pooling has contributed greatly to an overall performance boost to the runtime by reducing copying and GC time. These same APIs are available to the developer so I'd imagine that it would be simple to build a non allocating network buffer reader. I have built a non-allocating video renderer before using the new APIs, for example.
1 comments
pkolaczk 2366 days ago
There exist libraries for native memory pooling in Java as well, and we're using them. I'm not saying low allocation code can't be done in C# or Java. But these languages don't give some nice tools that are present in C++ and Rust - in particular RAII and automatic reference counting.
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masklinn 2366 days ago
> I'm not saying low allocation code can't be done in C# or Java.

With modern tools and APIs it should even be possible to write alloc-free work loops in C# (though you're probably writing pretty alien C# at this point). AFAIK it'll remain impossible in Java until the "value types" effort bears fruits.

A few months back a study of sort made the rounds implementing a network driver in multiple languages (Ixy), C# did extremely well in it (better throughput than Go and near competitive with C and Rust at higher batch size though it was way behind on latency) while Java was pretty much in the dumps.

In one of the reaction threads (don't remember if it was on HN or Reddit) one of the people involved explained the discrepancy between Java and C# by not being able to go under ~20 bytes of allocation per packet forwarded in Java.

There were other odd / interesting results from the effort e.g. Rust was slightly slower than C, in investigating that they found out Rust executed way more instructions (especially significantly more stores) but had significantly higher IPC and much higher cache hit rates.

ixy also tried just converting the C code to Rust (using C2Rust) then compiling it and that turned out to be very slightly faster than the C code, which was funny: https://github.com/ixy-languages/ixy-languages/blob/master/R...

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