Switch PatternMatcher to use a TemporaryArray instead of ArrayBuilder. #69784
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The customer completion profile that I'm looking at shows 5.6% of allocations and 0.7% of CPU in VS during the completion request period are due to allocations in ArrayBuilder.AllocateSlow. Simple testing on my machine shows > 20,000 roughly concurrent calls to TryUpperCaseCamelCaseMatch, only six of which end up with a non-empty matchedSpans (of size 2 in my test scenario). Instead of hitting some allocations in ArrayBuilder due to such heavy concurrent usage, instead just TemporaryArray which uses stack space for the common case of small arrays.
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The customer completion profile that I'm looking at shows 5.6% of allocations and 2.1% of CPU in VS during the completion request period are due to allocations in ArrayBuilder.AllocateSlow.
Simple testing on my machine shows > 20,000 roughly concurrent calls to TryUpperCaseCamelCaseMatch, only six of which end up with a non-empty matchedSpans (of size 2 in my test scenario). Instead of hitting some allocations in ArrayBuilder due to such heavy concurrent usage, instead just TemporaryArray which uses stack space for the common case of small arrays.