Use System.Buffers + ValueTask in FormReading #556

benaadams · 2016-02-07T09:44:26Z

Built on #550
Addressing Task allocations in #553 (last commit in this PR)

ValueTask reduces Task allocation by FormReader to 1%
Post for 30,000 requests - byte[] allocations are as follows 0.5MB on rent vs 440MB on MemoryStream originally

/cc @rynowak @davidfowl @Tratcher @stephentoub

stephentoub · 2016-02-07T14:26:57Z

This is because ValueTask isn't supported in net451

Why? The main point of putting it in a new assembly was so it would be usable there:
https://github.com/dotnet/corefx/blob/master/src/System.Threading.Tasks.Extensions/src/System.Threading.Tasks.Extensions.csproj#L9

benaadams · 2016-02-07T19:18:30Z

This is because ValueTask isn't supported in net451

Why? The main point of putting it in a new assembly was so it would be usable there:

Entirely my fault as I couldn't follow instructions; when it said it needed "System.Threading.Tasks": "4.0.0.0" it literally meant exactly that, not "System.Threading.Tasks": "4.0.0-*"

benaadams · 2016-02-11T11:18:46Z

Work done

Current

Buffers + ValueTask

benaadams · 2016-02-11T12:00:24Z

ValueTask reduces Task allocation by FormReader to 1% which continues to be amortised over time downwards #553 (comment)

Revisiting the original allocation issue from 30,000 requests (x10 on original)

ValueTask dramatically reduces the Task allocations to around 1% of the current (7MB vs 750MB)

benaadams · 2016-02-11T12:24:30Z

Pre-for 3,000 requests 44MB on MemoryStream

Post for 30,000 requests - byte[] allocations are as follows 0.5MB on rent vs 440MB on MemoryStream originally

rynowak · 2016-02-11T15:38:51Z

Nice 👍

benaadams · 2016-03-02T07:28:26Z

Rebased; removed WebEncoders changes as its changed somewhat.

sajayantony · 2016-03-02T08:15:07Z

Sweet 👍 /cc @DavidObando @mnltejaswini

DavidObando · 2016-03-02T18:19:02Z

Love this.

rynowak · 2016-03-02T20:06:54Z

src/Microsoft.AspNetCore.WebUtilities/FileBufferingReadStream.cs

@@ -43,6 +56,17 @@ public class FileBufferingReadStream : Stream
                throw new ArgumentNullException(nameof(tempFileDirectoryAccessor));
            }

+            _bytePool = bytePool;
+            if (memoryThreshold < 1024 * 1024)


Would be nice to put this in a constant.

benaadams · 2016-03-07T22:13:24Z

Rebased, somewhat squashed, feedback changes made

benaadams · 2016-03-07T22:21:45Z

src/Microsoft.AspNetCore.WebUtilities/FormReader.cs

+            using (reader)
+            {
+                var pair = await pairTask;
+                while (pair.HasValue)


how does this work? Am I missing something that way over my head?

@rynowak do you mean the splitting of the async version from the non-async version (until it becomes async) or the end of read being indicated by a null?

I just hadn't read these two lines super well.

I imagine a golden time in the future when the compiler automatically does these patterns for you...

davidfowl · 2016-03-14T15:52:54Z

@benaadams Can you rebase?

benaadams · 2016-03-14T17:00:55Z

Rebased; note: I had to bump src/Microsoft.Net.Http.Headers/project.json from "netstandard1.0" to "netstandard1.1"

davidfowl · 2016-03-14T17:06:57Z

src/Microsoft.AspNetCore.WebUtilities/project.json

  },
  "frameworks": {
    "net451": {
      "frameworkAssemblies": {
-        "System.Runtime": { "type": "build" }
+        "System.Runtime": { "type": "build" },
+        "System.Threading.Tasks": "4.0.0.0"


This needs to be type build like the other facades

muratg · 2016-03-17T21:28:35Z

src/Microsoft.AspNetCore.Owin/WebSockets/OwinWebSocketAdapter.cs

+                    // Drain until close received
+                    await ReceiveAsync(new ArraySegment<byte>(buffer), cancellationToken);
+                }
+            }


Would this ever actually throw?

Potentially, could throw if socket already disconnected or cancellation token cancelled.

Tratcher · 2016-03-22T19:25:39Z

This ValueTask pattern causes substantial code duplication and maintenance issues. I don't think it's piratical. Can we split this and just take the buffer pooling?

benaadams · 2016-03-22T19:38:13Z

This ValueTask pattern causes substantial code duplication and maintenance issues. I don't think it's piratical.

The ValueTask does cut the allocations on 30k requests from 750MB to 7MB though

/cc @rynowak

Tratcher · 2016-03-22T19:49:30Z

The buffer pooling is ready to merge and unrelated to the ValueTask work. Let's get that merged.

We need to come up with a simpler pattern if we're going to use ValueTasks.

benaadams · 2016-03-22T19:51:17Z

K, will split them later today

benaadams · 2016-03-23T13:11:29Z

We need to come up with a simpler pattern if we're going to use ValueTasks.

Know what you mean, there are a bunch of higher performance patterns with async that do make the code more confusing as you need to split the code into multiple fragments.

I wonder if there is scope to push this into the compiler instead? As it already does that for general async.

Would rosyln be the correct repo to raise this? /cc @stephentoub

stephentoub · 2016-03-23T13:13:04Z

Would roslyn be the correct repo to raise this?

dotnet/roslyn#7169

Tratcher · 2016-03-30T22:14:45Z

I recommend we close this pending the roslyn discussion. @benaadams @rynowak?

rynowak · 2016-03-30T23:02:32Z

That seems fine, I don't think we're going to take this PR in it's current form

dnfclas added the cla-already-signed label Feb 7, 2016

benaadams force-pushed the bufferpool-valuetask branch from 8ff6275 to 28b6cd9 Compare February 7, 2016 09:53

benaadams force-pushed the bufferpool-valuetask branch from 28b6cd9 to 25c7ac3 Compare February 7, 2016 19:16

benaadams mentioned this pull request Feb 7, 2016

Allocations in FormReader #553

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benaadams force-pushed the bufferpool-valuetask branch 2 times, most recently from 8d79967 to 88ec9fa Compare February 11, 2016 10:18

benaadams mentioned this pull request Feb 11, 2016

Use System.Buffers #550

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benaadams mentioned this pull request Feb 11, 2016

Allocations in FileBufferingReadStream #548

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benaadams force-pushed the bufferpool-valuetask branch from 88ec9fa to 1db60b9 Compare March 2, 2016 07:27

rynowak reviewed Mar 2, 2016
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benaadams force-pushed the bufferpool-valuetask branch 2 times, most recently from 0a5c6b9 to f270c45 Compare March 7, 2016 22:08

benaadams reviewed Mar 7, 2016
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benaadams changed the title ~~Use ValueTask in FormReading~~ Use ValueTask in FormReading + System.Buffers Mar 8, 2016

benaadams changed the title ~~Use ValueTask in FormReading + System.Buffers~~ Use System.Buffers + ValueTask in FormReading Mar 8, 2016

benaadams added 3 commits March 14, 2016 12:23

Use System.Buffers for temporary arrays

70a8b61

Use ValueTask in FormReading

3307eeb

Introduce constants for buffer sizes

ff075e9

benaadams force-pushed the bufferpool-valuetask branch from f270c45 to ff075e9 Compare March 14, 2016 16:28

davidfowl reviewed Mar 14, 2016
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System.Threading.Tasks -> build

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muratg reviewed Mar 17, 2016
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Tratcher self-assigned this Mar 22, 2016

benaadams mentioned this pull request Mar 22, 2016

Use System.Buffers for temporary arrays #595

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Tratcher closed this Mar 30, 2016

ljw1004 mentioned this pull request May 19, 2016

Discussion thread for arbitrary async returns dotnet/roslyn#10902

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Use System.Buffers + ValueTask in FormReading #556

Use System.Buffers + ValueTask in FormReading #556

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Use System.Buffers + ValueTask in FormReading #556

Use System.Buffers + ValueTask in FormReading #556

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