netty/netty — pull request #2831 by normanmaurer (2014-08-27 08:10:04+00:00)
Title: Modify HttpObjectDecoder to allow parsing the HTTP headers in multiple s...

...teps.

Motivation:
At the moment the whole HTTP header must be parsed at once which can lead to multiple parsing of the same bytes. We can do better here and allow to parse it in multiple steps.

Modifications:

- Not parse headers multiple times
- Simplify the code
- Eliminate uncessary String[] creations
- Use readSlice(...).retain() when possible.

Result:

Performance improvements as shown in the included benchmark below.

Before change:
[nmaurer@xxx]~% ./wrk-benchmark
Running 2m test @ http://xxx:8080/plaintext
16 threads and 256 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 21.55ms 15.10ms 245.02ms 90.26%
Req/Sec 196.33k 30.17k 297.29k 76.03%
373954750 requests in 2.00m, 50.15GB read
Requests/sec: 3116466.08
Transfer/sec: 427.98MB

After change:
[nmaurer@xxx]~% ./wrk-benchmark
Running 2m test @ http://xxx:8080/plaintext
16 threads and 256 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 20.91ms 36.79ms 1.26s 98.24%
Req/Sec 206.67k 21.69k 243.62k 94.96%
393071191 requests in 2.00m, 52.71GB read
Requests/sec: 3275971.50
Transfer/sec: 449.89MB