Performance regression when deserializing compressed binary XML streams using data contract serializers

[dev991301]

Description

When compared to .NET Framework 4.8, the output from BenchmarkDotNet shows execution time has greatly increased in .NET6/7 when deserializing from compressed binary XML streams using data contract serializers for large collections of objects (>1000). For example, using my configuration, deserializing 10,000 objects is around 200 times slower in .NET6/7 when compared to .NET Framework 4.8.

Data Contract Code

[DataContract(IsReference = true)]
public class Person
{
    [DataMember]
    public Person Parent { get; set; }
    
    [DataMember]
    public List<Person> Children { get; set; }
}

Benchmark Code

[SimpleJob(RuntimeMoniker.Net48, baseline: true)]
[SimpleJob(RuntimeMoniker.Net60)]
[SimpleJob(RuntimeMoniker.Net70)]
public class Benchmark
{
    [Params(10, 100, 1000, 10000)]
    public int N { get; set; }

    private byte[] _serialized;
    private readonly DataContractSerializer _serializer = new (typeof(Person));

    [GlobalSetup]
    public void Serialize()
    {
        var person = new Person();
        person.Children = Enumerable.Range(0, N-1).Select(_ => new Person {Parent = person}).ToList();

        using var compressed = new MemoryStream();
        using var compressor = new DeflateStream(compressed, CompressionMode.Compress);
        
        using var writer = XmlDictionaryWriter.CreateBinaryWriter(compressor);
        _serializer.WriteObject(writer, person);
        writer.Close();
        
        _serialized =  compressed.ToArray();
    }
    
    [Benchmark]
    public object Deserialize()
    {
        using var compressed = new MemoryStream(_serialized);
        using var decompressor = new DeflateStream(compressed, CompressionMode.Decompress);
        
        using var reader = XmlDictionaryReader.CreateBinaryReader(decompressor, XmlDictionaryReaderQuotas.Max);
        
        return _serializer.ReadObject(reader);
    }
}

Configuration

BenchmarkDotNet=v0.13.2, OS=Windows 11 (10.0.22000.856/21H2)
11th Gen Intel Core i7-11800H 2.30GHz, 1 CPU, 16 logical and 8 physical cores
.NET SDK=7.0.100-preview.7.22377.5
  [Host]             : .NET 7.0.0 (7.0.22.37506), X64 RyuJIT AVX2
  .NET 6.0           : .NET 6.0.8 (6.0.822.36306), X64 RyuJIT AVX2
  .NET 7.0           : .NET 7.0.0 (7.0.22.37506), X64 RyuJIT AVX2
  .NET Framework 4.8 : .NET Framework 4.8 (4.8.4510.0), X64 RyuJIT VectorSize=256

Data

Method	Job	Runtime	N	Mean	Error	StdDev	Ratio	RatioSD
Deserialize	.NET 6.0	.NET 6.0	10	29.06us	0.256us	0.227us	0.82	0.01
Deserialize	.NET 7.0	.NET 7.0	10	28.99us	0.318us	0.297us	0.82	0.01
Deserialize	.NET Framework 4.8	.NET Framework 4.8	10	35.42us	0.253us	0.211us	1.00	0.00
Deserialize	.NET 6.0	.NET 6.0	100	323.17us	2.265us	2.008us	1.19	0.01
Deserialize	.NET 7.0	.NET 7.0	100	319.55us	2.648us	2.348us	1.17	0.01
Deserialize	.NET Framework 4.8	.NET Framework 4.8	100	272.22us	2.486us	2.204us	1.00	0.00
Deserialize	.NET 6.0	.NET 6.0	1000	310,428.48us	914.629us	810.795us	116.82	0.81
Deserialize	.NET 7.0	.NET 7.0	1000	312,653.03us	2,976.487us	2,638.578us	117.73	1.04
Deserialize	.NET Framework 4.8	.NET Framework 4.8	1000	2,657.57us	18.909us	15.790us	1.00	0.00
Deserialize	.NET 6.0	.NET 6.0	10000	6,167,079.07us	28,492.478us	26,651.882us	214.41	2.02
Deserialize	.NET 7.0	.NET 7.0	10000	6,140,992.62us	13,397.507us	11,187.525us	213.47	2.17
Deserialize	.NET Framework 4.8	.NET Framework 4.8	10000	28,765.16us	293.030us	274.100us	1.00	0.00

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[filipnavara]

Can you try wrapping the DeflateStream with BufferedStream? I have seen half a dozen similar regressions due to the fact that the buffering works differently. For consumers that use small reads it could often make a huge difference.

[stephentoub]

Yes, this is the same as #39233. Here Deserialize is your benchmark and Deserialize2 is your benchmark but with a BufferedStream added in between:

Method	Runtime	N	Mean	Ratio
Deserialize	.NET Framework 4.8	10000	37.77 ms	1.00
Deserialize	.NET 6.0	10000	381.80 ms	10.10
Deserialize2	.NET Framework 4.8	10000	14.35 ms	1.00
Deserialize2	.NET 6.0	10000	11.17 ms	0.78

[dev991301]

Thank you for the help. Using the BufferedStream does indeed significantly improve the performance.

I am porting a large code base from .NET Framework 4.8 to .NET 6 and came across this issue. I am not sure if there are other issues that could have negative performance implications when porting from Framework. Is there documentation I should have read that highlights potential performance regressions when porting from Framework and the solutions?

Thanks again for your help.

[danmoseley]

@PriyaPurkayastha do we have a place for such info? @StephenBonikowsky I know such migration bumps are something you have an interest in also. This is similar to the discussion we had in #72266 - where do we record speed bumps that aren't breaking by a stricter definition. Cc @ericstj

[PriyaPurkayastha]

@danmoseley I am aware of "What's New in .NET 6", "Known Issues" and "Breaking changes" published per release. It appears that nobody is comfortable using the existing documentation channels for such issues, so we might just need to figure out a path forward. Since such speed bumps might be spread out over different Fundamental areas, I think it would be valuable to hear the opinions/thoughts from respective Fundamentals area owners. e.g This one as well as #72266 would be something that we can talk to @sblom about. I will start a discussion on this and also include documentation team since they have valuable inputs as well.
cc @marklio

[stephentoub]

I am aware of "What's New in .NET 6", "Known Issues" and "Breaking changes" published per release. It appears that nobody is comfortable using the existing documentation channels for such issues,

I think this makes sense as a known issue; we certainly didn't want this particular usage to be so much slower, and it happened because of a change in one of our dependencies. The downside is it'll likely be a known issue in several releases, as long as we're using that dependency and it itself makes the same tradeoffs it currently does.

Tagging subscribers to this area: @dotnet/area-system-io
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

When compared to .NET Framework 4.8, the output from BenchmarkDotNet shows execution time has greatly increased in .NET6/7 when deserializing from compressed binary XML streams using data contract serializers for large collections of objects (>1000). For example, using my configuration, deserializing 10,000 objects is around 200 times slower in .NET6/7 when compared to .NET Framework 4.8.

Data Contract Code

[DataContract(IsReference = true)]
public class Person
{
    [DataMember]
    public Person Parent { get; set; }
    
    [DataMember]
    public List<Person> Children { get; set; }
}

Benchmark Code

[SimpleJob(RuntimeMoniker.Net48, baseline: true)]
[SimpleJob(RuntimeMoniker.Net60)]
[SimpleJob(RuntimeMoniker.Net70)]
public class Benchmark
{
    [Params(10, 100, 1000, 10000)]
    public int N { get; set; }

    private byte[] _serialized;
    private readonly DataContractSerializer _serializer = new (typeof(Person));

    [GlobalSetup]
    public void Serialize()
    {
        var person = new Person();
        person.Children = Enumerable.Range(0, N-1).Select(_ => new Person {Parent = person}).ToList();

        using var compressed = new MemoryStream();
        using var compressor = new DeflateStream(compressed, CompressionMode.Compress);
        
        using var writer = XmlDictionaryWriter.CreateBinaryWriter(compressor);
        _serializer.WriteObject(writer, person);
        writer.Close();
        
        _serialized =  compressed.ToArray();
    }
    
    [Benchmark]
    public object Deserialize()
    {
        using var compressed = new MemoryStream(_serialized);
        using var decompressor = new DeflateStream(compressed, CompressionMode.Decompress);
        
        using var reader = XmlDictionaryReader.CreateBinaryReader(decompressor, XmlDictionaryReaderQuotas.Max);
        
        return _serializer.ReadObject(reader);
    }
}

Configuration

BenchmarkDotNet=v0.13.2, OS=Windows 11 (10.0.22000.856/21H2)
11th Gen Intel Core i7-11800H 2.30GHz, 1 CPU, 16 logical and 8 physical cores
.NET SDK=7.0.100-preview.7.22377.5
  [Host]             : .NET 7.0.0 (7.0.22.37506), X64 RyuJIT AVX2
  .NET 6.0           : .NET 6.0.8 (6.0.822.36306), X64 RyuJIT AVX2
  .NET 7.0           : .NET 7.0.0 (7.0.22.37506), X64 RyuJIT AVX2
  .NET Framework 4.8 : .NET Framework 4.8 (4.8.4510.0), X64 RyuJIT VectorSize=256

Data

Method	Job	Runtime	N	Mean	Error	StdDev	Ratio	RatioSD
Deserialize	.NET 6.0	.NET 6.0	10	29.06us	0.256us	0.227us	0.82	0.01
Deserialize	.NET 7.0	.NET 7.0	10	28.99us	0.318us	0.297us	0.82	0.01
Deserialize	.NET Framework 4.8	.NET Framework 4.8	10	35.42us	0.253us	0.211us	1.00	0.00
Deserialize	.NET 6.0	.NET 6.0	100	323.17us	2.265us	2.008us	1.19	0.01
Deserialize	.NET 7.0	.NET 7.0	100	319.55us	2.648us	2.348us	1.17	0.01
Deserialize	.NET Framework 4.8	.NET Framework 4.8	100	272.22us	2.486us	2.204us	1.00	0.00
Deserialize	.NET 6.0	.NET 6.0	1000	310,428.48us	914.629us	810.795us	116.82	0.81
Deserialize	.NET 7.0	.NET 7.0	1000	312,653.03us	2,976.487us	2,638.578us	117.73	1.04
Deserialize	.NET Framework 4.8	.NET Framework 4.8	1000	2,657.57us	18.909us	15.790us	1.00	0.00
Deserialize	.NET 6.0	.NET 6.0	10000	6,167,079.07us	28,492.478us	26,651.882us	214.41	2.02
Deserialize	.NET 7.0	.NET 7.0	10000	6,140,992.62us	13,397.507us	11,187.525us	213.47	2.17
Deserialize	.NET Framework 4.8	.NET Framework 4.8	10000	28,765.16us	293.030us	274.100us	1.00	0.00

Author:	dev991301
Assignees:	-
Labels:	area-Serialization, area-System.IO, tenet-performance, untriaged
Milestone:	-

[StephenMolloy]

Moving this to System.IO so the appropriate team can decide how they want to document this recommendation for BufferedStream when moving from 6.0 -> 7.0.