Tutorial Zero-Allocation JSON Serialization with Utf8JsonWriter and IBufferWriter<byte> - UnreliableCode Forums

JsonSpeedster

Serialization & I/O

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2y ago · Aug 25, 2023 2:10 PM

#1

Standard

CODE

JsonSerializer.Serialize()

produces a

CODE

string

, which requires a UTF-16 heap allocation and subsequent UTF-8 encoding when writing to a network socket.

How to write JSON directly into UTF-8 byte streams with zero string allocations:

CSHARP

using System.Buffers;
using System.Text.Json;

public static class FastJsonSerializer
{
    public static void WritePlayerState(IBufferWriter<byte> bufferWriter, int playerId, string username, float health)
    {
        using var writer = new Utf8JsonWriter(bufferWriter, new JsonWriterOptions { Indented = false });
        
        writer.WriteStartObject();
        writer.WriteNumber("id", playerId);
        writer.WriteString("user", username);
        writer.WriteNumber("hp", health);
        writer.WriteBoolean("alive", health > 0);
        writer.WriteEndObject();
        
        writer.Flush();
    }
}

Combining

CODE

Utf8JsonWriter

with an

CODE

ArrayBufferWriter<byte>

gives you raw bytes ready to send over WebSockets or TCP immediately!

Standard [code]JsonSerializer.Serialize()[/code] produces a [code]string[/code], which requires a UTF-16 heap allocation and subsequent UTF-8 encoding when writing to a network socket.

[b]How to write JSON directly into UTF-8 byte streams with zero string allocations:[/b]

[code=csharp]using System.Buffers;
using System.Text.Json;

public static class FastJsonSerializer
{
    public static void WritePlayerState(IBufferWriter<byte> bufferWriter, int playerId, string username, float health)
    {
        using var writer = new Utf8JsonWriter(bufferWriter, new JsonWriterOptions { Indented = false });
        
        writer.WriteStartObject();
        writer.WriteNumber("id", playerId);
        writer.WriteString("user", username);
        writer.WriteNumber("hp", health);
        writer.WriteBoolean("alive", health > 0);
        writer.WriteEndObject();
        
        writer.Flush();
    }
}[/code]

Combining [code]Utf8JsonWriter[/code] with an [code]ArrayBufferWriter<byte>[/code] gives you raw bytes ready to send over WebSockets or TCP immediately!

JsonSpeedster · Serialization & I/O
High-throughput JSON parsing with System.Text.Json, Utf8Json...

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BytePusher

Memory & Performance

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2y ago · Aug 25, 2023 3:47 PM

#2

Pairing

CODE

Utf8JsonWriter

with

CODE

ReadOnlySpan<byte>

property names (e.g.

CODE

writer.WriteString("user"u8, username)

using C# 11 UTF-8 string literals) eliminates even the string constant decoding step!

BytePusher · Memory & Performance
Zero-allocation C# code using Span<T>, Memory<T>, and Unsafe...

CSharpNinja

Senior .NET Developer

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2y ago · Aug 25, 2023 7:47 PM

#3

UTF-8 string literals with the

CODE

"name"u8

suffix are so underrated. The compiler bakes the exact UTF-8 bytes directly into the binary assembly as a

CODE

ReadOnlySpan<byte>

.

CSharpNinja · Senior .NET Developer
C# enthusiast, building distributed backend services and hig...

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Zero-Allocation JSON Serialization with Utf8JsonWriter and IBufferWriter<byte>

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