Use RecyclableMemoryStream

[JimBobSquarePants]

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A replacement for #106 that uses RecyclableMemoryStream for buffer pooling.

Note. Suggestions welcome for default pooling configuration values.

[codecov]

Codecov Report

Merging #107 into master will increase coverage by 0.82%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #107      +/-   ##
==========================================
+ Coverage   77.19%   78.01%   +0.82%     
==========================================
  Files          46       45       -1     
  Lines        1324     1128     -196     
  Branches      211      174      -37     
==========================================
- Hits         1022      880     -142     
+ Misses        238      191      -47     
+ Partials       64       57       -7     

Flag	Coverage Δ
#unittests	78.01% <100.00%> (+0.82%)	⬆️

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Impacted Files	Coverage Δ
...rc/ImageSharp.Web/Commands/ComparableExtensions.cs	16.66% <ø> (ø)
...s.Azure/Providers/AzureBlobStorageImageProvider.cs	78.72% <100.00%> (+1.45%)	⬆️
...s.Azure/Resolvers/AzureBlobStorageImageResolver.cs	92.30% <100.00%> (+2.30%)	⬆️
...ndencyInjection/ImageSharpCoreBuilderExtensions.cs	78.12% <100.00%> (+2.26%)	⬆️
...DependencyInjection/ServiceCollectionExtensions.cs	86.95% <100.00%> (+0.59%)	⬆️
.../ImageSharp.Web/Middleware/ImageSharpMiddleware.cs	71.42% <100.00%> (-1.06%)	⬇️
...harp.Web/Middleware/ImageSharpMiddlewareOptions.cs	57.69% <100.00%> (+1.69%)	⬆️

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[antonfirsov]

Looks good, and we are likely fine with the default setup.

RecyclableMemoryStream docs state:

Large Pool - Holds large buffers, which are only used when you must have a single, contiguous buffer, such as when you plan to call GetBuffer().

So, if no-one will invoke stream.(Try)GetBuffer, all streams are puzzled together from 128 kbyte, small buffers, and the large pools remain untouched.

Note the reasoning behind that buffer size selection:

RecyclableMemoryStream improves GC performance by ensuring that the larger buffers used for the streams are put into the gen 2 heap and stay there forever. This should cause full collections to happen less frequently. If you pick buffer sizes above 85,000 bytes, then you will ensure these are placed on the large object heap, which is touched even less frequently by the garbage collector.

We need to adapt this size in ChunkedMemoryStream!

[JimBobSquarePants]

We need to adapt this size in ChunkedMemoryStream!

Yep!