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Avoid delegate allocation in TraceSourceLoggerProvider.GetOrAddTraceSource #71134

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stephentoub merged 1 commit into from
Jun 22, 2022
Merged

Avoid delegate allocation in TraceSourceLoggerProvider.GetOrAddTraceSource #71134

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7 changes: 3 additions & 4 deletions src/libraries/Microsoft.Extensions.Logging.TraceSource/src/TraceSourceLoggerProvider.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -53,10 +53,9 @@ public ILogger CreateLogger(string name)
return new TraceSourceLogger(GetOrAddTraceSource(name));
}

private DiagnosticsTraceSource GetOrAddTraceSource(string name)
{
return _sources.GetOrAdd(name, InitializeTraceSource);
}
private DiagnosticsTraceSource GetOrAddTraceSource(string name) =>
_sources.TryGetValue(name, out DiagnosticsTraceSource? source) ? source :
_sources.GetOrAdd(name, InitializeTraceSource(name));
Comment on lines +57 to +58
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@eerhardt eerhardt Jun 22, 2022

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It feels like this is such a perf trap ... 99.9% of devs would write the code as it was originally.

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@stephentoub stephentoub Jun 22, 2022

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If InitializeTraceSource was static, it'd be ok (as of C# 11 and its caching of method group delegates). But as an instance method, the compiler is forced to allocate a new delegate. That's the nature of implicit delegate conversions.

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@sharwell sharwell Jun 22, 2022 •
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The other option here is:

_sources.GetOrAdd(name, static (name, self) => self.InitializeTraceSource(name), this)

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@sharwell sharwell Jun 22, 2022

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It feels like this is such a perf trap

It's been this way for a very, very long time. Since most code won't have an observable perf impact of a delegate allocation in a call like this, it hasn't been too big a deal for most of that time (IMO of course).

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@stephentoub stephentoub Jun 22, 2022

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The other option here is

This library has a netstandard2.0 target.


private DiagnosticsTraceSource InitializeTraceSource(string traceSourceName)
{
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