Tracking bug for continuing to improve CPU and memory allocations in the net/http server.

I was just starting to have fun when it was time to ship Go 1.1.

Here's where we're at:

~/go/src/pkg/net/http$ hg id
8153882a36e8 tip

~/go/src/pkg/net/http$ go test -c

~/go/src/pkg/net/http$ ./http.test -test.v -test.run=none -test.bench=ServerHandler
-test.cpuprofile=prof.cpu -test.benchtime=4s
PASS
BenchmarkServerHandlerTypeLen    1000000         11098 ns/op        1878 B/op         19 allocs/op
BenchmarkServerHandlerNoLen  1000000         10249 ns/op        1843 B/op         17 allocs/op
BenchmarkServerHandlerNoType     1000000         10620 ns/op        1844 B/op         17 allocs/op
BenchmarkServerHandlerNoHeader   1000000          8674 ns/op        1051 B/op         12 allocs/op

4 CPUs:
processor   : 3
vendor_id   : GenuineIntel
cpu family  : 6
model       : 37
model name  : Intel(R) Core(TM) i5 CPU       M 560  @ 2.67GHz
stepping    : 5
microcode   : 0x2
cpu MHz     : 2667.000
cache size  : 3072 KB

(pprof) top25
Total: 3883 samples
     319   8.2%   8.2%      319   8.2% runtime.memmove
     133   3.4%  11.6%      171   4.4% time.nextStdChunk
     113   2.9%  14.6%      415  10.7% time.Time.Format
      93   2.4%  16.9%     1130  29.1% net/http.(*chunkWriter).writeHeader
      87   2.2%  19.2%      616  15.9% runtime.mallocgc
      86   2.2%  21.4%      111   2.9% sweepspan
      82   2.1%  23.5%      114   2.9% scanblock
      81   2.1%  25.6%      213   5.5% runtime.MCache_Alloc
      81   2.1%  27.7%       87   2.2% runtime.settype_flush
      78   2.0%  29.7%       78   2.0% net/textproto.CanonicalMIMEHeaderKey
      72   1.9%  31.5%       72   1.9% net/textproto.canonicalMIMEHeaderKey
      72   1.9%  33.4%       72   1.9% runtime.markallocated
      69   1.8%  35.2%       80   2.1% itab
      68   1.8%  36.9%       68   1.8% runtime.xchg
      58   1.5%  38.4%       58   1.5% runtime.memclr
      57   1.5%  39.9%      272   7.0% hash_insert
      56   1.4%  41.3%     1409  36.3% net/http.ReadRequest
      51   1.3%  42.6%       60   1.5% time.appendUint
      48   1.2%  43.9%      205   5.3% net/http.readTransfer
      47   1.2%  45.1%       47   1.2% runtime.appendstr
      42   1.1%  46.2%       42   1.1% bytes.IndexByte
      39   1.0%  47.2%      218   5.6% bufio.(*Writer).Write
      39   1.0%  48.2%       44   1.1% hash_init
      38   1.0%  49.2%       50   1.3% hash_remove
      37   1.0%  50.1%      209   5.4% runtime.copy

(pprof) top25 --cum
Total: 3883 samples
       0   0.0%   0.0%     3594  92.6% gosched0
      23   0.6%   0.6%     3593  92.5% net/http.(*conn).serve
      20   0.5%   1.1%     1593  41.0% net/http.(*conn).readRequest
      56   1.4%   2.5%     1409  36.3% net/http.ReadRequest
      13   0.3%   2.9%     1318  33.9% net/http.(*response).finishRequest
      20   0.5%   3.4%     1240  31.9% bufio.(*Writer).Flush
      10   0.3%   3.7%     1222  31.5% net/http.(*switchWriter).Write
      17   0.4%   4.1%     1207  31.1% net/http.(*chunkWriter).Write
      93   2.4%   6.5%     1130  29.1% net/http.(*chunkWriter).writeHeader
      13   0.3%   6.8%      627  16.1% net/http.serverHandler.ServeHTTP
      87   2.2%   9.1%      616  15.9% runtime.mallocgc
      11   0.3%   9.3%      607  15.6% net/http_test.func·112
       6   0.2%   9.5%      603  15.5% net/http.HandlerFunc.ServeHTTP
      27   0.7%  10.2%      514  13.2% net/textproto.(*Reader).ReadMIMEHeader
      24   0.6%  10.8%      431  11.1% net/http.(*response).Write
     113   2.9%  13.7%      415  10.7% time.Time.Format
      28   0.7%  14.4%      332   8.6% runtime.new
      16   0.4%  14.9%      331   8.5% runtime.mapassign
     319   8.2%  23.1%      319   8.2% runtime.memmove
      15   0.4%  23.5%      304   7.8% net/http.(*response).WriteHeader
      14   0.4%  23.8%      290   7.5% runtime.mapassign1
      57   1.5%  25.3%      272   7.0% hash_insert
       4   0.1%  25.4%      249   6.4% net/http_test.func·108
      34   0.9%  26.3%      243   6.3% net/http.Header.WriteSubset
       8   0.2%  26.5%      235   6.1% net/http.Header.clone


And an svg/png of CPU attached.

I'll attach a CPU one later with GOGC=off.

Attachments:

1. http.svg (104237 bytes)
2. http.png (709313 bytes)