Reduce string allocations in XmlWriterTraceListener

[stephentoub]

Rather than ToString'ing everything, most of the header data can be formatted into a span and then written out to the writer.

usingBenchmarkDotNet.Attributes;usingBenchmarkDotNet.Running;usingSystem.Diagnostics;usingSystem.IO;[MemoryDiagnoser]publicclassProgram{staticvoidMain(string[]args)=>BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args);privateXmlWriterTraceListener_listener=newXmlWriterTraceListener(Stream.Null);privateTraceEventCache_cache=newTraceEventCache();[Benchmark]publicvoidTrace(){_listener.TraceEvent(_cache,"something",TraceEventType.Information,42);}}

Method	Toolchain	Mean	Error	Ratio	Allocated
Trace	\main\corerun.exe	585.9 ns	9.29 ns	1.00	272 B
Trace	\pr\corerun.exe	481.7 ns	3.88 ns	0.82	24 B

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Issue Details

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Rather than ToString'ing everything, most of the header data can be formatted into a span and then written out to the writer.

usingBenchmarkDotNet.Attributes;usingBenchmarkDotNet.Running;usingSystem.Diagnostics;usingSystem.IO;[MemoryDiagnoser]publicclassProgram{staticvoidMain(string[]args)=>BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args);privateXmlWriterTraceListener_listener=newXmlWriterTraceListener(Stream.Null);privateTraceEventCache_cache=newTraceEventCache();[Benchmark]publicvoidTrace(){_listener.TraceEvent(_cache,"something",TraceEventType.Information,42);}}

Method	Toolchain	Mean	Error	Ratio	Allocated
Trace	\main\corerun.exe	585.9 ns	9.29 ns	1.00	272 B
Trace	\pr\corerun.exe	481.7 ns	3.88 ns	0.82	24 B

Author:	stephentoub
Assignees:	stephentoub
Labels:	area-System.Xml
Milestone:	-