Avoid buffering during input formatting for longer than necessary

[pranavkm]

EnableRewind uses FileBufferingReadStream which is not disposed until the response is completed.
This results in holding on to internal buffers for significantly longer than necessary. Changing it
to return the buffers immediately improved the allocations and throughput.

Description	RPS	CPU (%)	Memory (MB)	Avg. Latency (ms)	Startup (ms)	First Request (ms)	Latency (ms)	Ratio
Newtonsoft.Json - old - 500 bytes	49,661	98	2,349	7.32	514	87.97	0.49	1.00
Newtonsoft.Json - new - 500 bytes	120,273	94	174	2.32	509	80.54	0.36	2.42
Newtonsoft.Json - old - 2k	29,759	97	382	9.11	556	80.14	0.5	1.00
Newtonsoft.Json - new - 2k	36,079	97	186	7.53	507	84.96	0.41	1.21
Newtonsoft.Json - old - 8 kbytes	29,784	98	343	9.41	506	81.49	0.36	1.00
Newtonsoft.Json - new - 8 kbytes	35,408	98	187	8.79	503	79.64	0.33	1.19
Newtonsoft.Json - old - 40 kbytes	2,937	76	2,004	89.87	512	89.18	0.49	1.00
Newtonsoft.Json - new - 40 kbytes	8,416	99	202	30.8	534	78.79	0.47	2.87

[pranavkm]

Just moved the ErrorHandler out of the try-catch block since it doesn't need to be there. Besides disposing the FileBufferingReadStream, the rest of this is unchanged.

[Tratcher]

What about the XML perf?

[dougbu]

Any particular thing you wanted me to look at @pranavkm?

[rynowak]

So what the impact of this if you wanted to rewind and reread the stream? Would you see a non-seekable stream that's at the end?

What's required if a user wants to enforce buffering (and allow rewinding)?

I'm asking because I'm sure someone has done this, and we're changing the default.

[pranavkm]

What's required if a user wants to enforce buffering (and allow rewinding)?

You can explicitly call EnableRewind in a middleware prior to getting to MVC and things should work as before. In fact, we avoid double buffering if we think the request stream is buffered.

[pranavkm]

🆙 📅