sunero4 opened a new pull request, #128:
URL: https://github.com/apache/pulsar-dotpulsar/pull/128
# Description
I recently started working at Danske Commodities where I had to use this
library, and decided to peek around the source code a bit to see what it does.
It seems to me that a significant amount of allocations could be avoided by not
copying the slice to a new array in `Connection.cs` line 311, as the slice
itself is already a `ReadOnlySequence<byte>`. I ran some simple benchmarks of
performing such a copy (benchmark code and results is found below) that
verifies that this indeed results in allocating the equivalent of the slice
once more.
Besides changing this, I looked through the project and found a few places
where the `static` modifier could be applied to reduce allocations for lambdas,
but there were very few of these, probably because LINQ seems to be used very
sparsely in the project.
# Benchmark results
```
| Method | Mean | Error | StdDev |
Gen0 | Allocated |
|-----------------------------------
|----------:|----------:|----------:|-------:|----------:|
| ReturnSliceDirectly (Input = 256 B) | 8.699 ns | 0.1168 ns
| 0.1093 ns | - | - |
| ReturnNewReadOnlySequenceFromArray (Input = 256 B) | 38.693 ns | 0.7455 ns
| 0.7322 ns | 0.0485 | 152 B |
| Method | Mean | Error | StdDev |
Gen0 | Allocated |
|-----------------------------------
|-----------:|----------:|----------:|-------:|----------:|
| ReturnSliceDirectly (Input = 2048 B) | 8.716 ns | 0.1092
ns | 0.1021 ns | - | - |
| ReturnNewReadOnlySequenceFromArray (Input = 2048 B) | 174.669 ns | 3.3067
ns | 3.3957 ns | 0.6194 | 1944 B |
| Method | Mean | Error |
StdDev | Gen0 | Allocated |
|-----------------------------------
|-------------:|-----------:|-----------:|--------:|----------:|
| ReturnSliceDirectly (Input = 65536 B) | 8.748 ns |
0.1240 ns | 0.1160 ns | - | - |
| ReturnNewReadOnlySequenceFromArray (Input = 65536 B) | 4,809.186 ns |
78.2922 ns | 73.2346 ns | 20.4010 | 65432 B |
```
# Benchmark code
```
using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;
using System.Buffers;
[MemoryDiagnoser]
public class Program
{
private static readonly ReadOnlySequence<byte> Input = new
ReadOnlySequence<byte>(new byte[65536]);
public static void Main()
{
BenchmarkRunner.Run<Program>();
Console.ReadLine();
}
[Benchmark]
public ReadOnlySequence<byte> ReturnSliceDirectly()
{
return Input.Slice(128);
}
[Benchmark]
public ReadOnlySequence<byte> ReturnNewReadOnlySequenceFromArray()
{
return new ReadOnlySequence<byte>(Input.Slice(128).ToArray());
}
}
```
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