Our way of pooling TokenBuilder leaks for multiple documents

[NTaylorMullen]

Basically we're not disposing this after acquiring from the pool:
https://github.com/dotnet/aspnetcore/blob/351a97dee8b7e29d775c6456e074812ae66141c5/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/TokenizerBackedParser.cs#L31-L43

@TanayParikh in your profiles have you seen this?

[TanayParikh]

in your profiles have you seen this?

Hadn't seen that. Fix seems pretty straightforward. Any objection in making the TokenizerBackedParser, IDisposable, and disposing of the PooledResult there? We'd have to persist the result obtained on line 37.

[NTaylorMullen]

I'm not 100% sure on how the _pool operates but if you Dispose doesn't that allow another entry to "lease" that builder?

[TanayParikh]

but if you Dispose doesn't that allow another entry to "lease" that builder?

It appears so:

1. Dispose
2. Builder is Free'd and cleared
3. And added back to pool for use by another entry

I'm not familiar enough with the parser to understand the consequences of re-using the builder. Would it be preferred to completely destroy it, rather than add back to pool?

[NTaylorMullen]

I'm not familiar enough with the parser to understand the consequences of re-using the builder. Would it be preferred to completely destroy it, rather than add back to pool?

Wouldn't be preferrable because we create these all over. The general idea is we'd want to add it back to the pool once the parser was done being used. That alone is something we haven't handled before though. I wonder if we just added a finalizer to our parser and released the result in that if it'd work.

[TanayParikh]

I've added this to the next steps under the perf big rock.

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