Merge bitcoin/bitcoin#30675: http: set TCP_NODELAY when creating HTTP server

03d49d0f25ab5660524d5ddd171de677a808b984 http: set TCP_NODELAY when creating HTTP server (Roman Zeyde)

Pull request description:

  Otherwise, the default HTTP server config may result in high latency, due to Nagle's algorithm (on the server) and delayed ACK (on the client):

  [1] https://www.extrahop.com/blog/tcp-nodelay-nagle-quickack-best-practices
  [2] https://eklitzke.org/the-caveats-of-tcp-nodelay

  Without the fix, fetching a small block takes ~40ms (when connection keep-alive is enabled):
  ```
  $ ab -k -c 1 -n 100 http://localhost:8332/rest/block/00000000000002b5898f7cdc80d9c84e9747bc6b9388cc989971d443f05713ee.bin

  Server Software:
  Server Hostname:        localhost
  Server Port:            8332

  Document Path:          /rest/block/00000000000002b5898f7cdc80d9c84e9747bc6b9388cc989971d443f05713ee.bin
  Document Length:        25086 bytes

  Concurrency Level:      1
  Time taken for tests:   4.075 seconds
  Complete requests:      100
  Failed requests:        0
  Keep-Alive requests:    100
  Total transferred:      2519200 bytes
  HTML transferred:       2508600 bytes
  Requests per second:    24.54 [#/sec] (mean)
  Time per request:       40.747 [ms] (mean)
  Time per request:       40.747 [ms] (mean, across all concurrent requests)
  Transfer rate:          603.76 [Kbytes/sec] received

  Connection Times (ms)
                min  mean[+/-sd] median   max
  Connect:        0    0   0.0      0       0
  Processing:     0   41   4.1     41      42
  Waiting:        0    0   0.1      0       1
  Total:          0   41   4.1     41      42

  Percentage of the requests served within a certain time (ms)
    50%     41
    66%     41
    75%     41
    80%     41
    90%     42
    95%     42
    98%     42
    99%     42
   100%     42 (longest request)
  ```

  With the fix, it takes ~0.2ms:
  ```
  $ ab -k -c 1 -n 1000 http://localhost:8332/rest/block/00000000000002b5898f7cdc80d9c84e9747bc6b9388cc989971d443f05713ee.bin

  Benchmarking localhost (be patient)
  Completed 100 requests
  Completed 200 requests
  Completed 300 requests
  Completed 400 requests
  Completed 500 requests
  Completed 600 requests
  Completed 700 requests
  Completed 800 requests
  Completed 900 requests
  Completed 1000 requests
  Finished 1000 requests

  Server Software:
  Server Hostname:        localhost
  Server Port:            8332

  Document Path:          /rest/block/00000000000002b5898f7cdc80d9c84e9747bc6b9388cc989971d443f05713ee.bin
  Document Length:        25086 bytes

  Concurrency Level:      1
  Time taken for tests:   0.194 seconds
  Complete requests:      1000
  Failed requests:        0
  Keep-Alive requests:    1000
  Total transferred:      25192000 bytes
  HTML transferred:       25086000 bytes
  Requests per second:    5147.05 [#/sec] (mean)
  Time per request:       0.194 [ms] (mean)
  Time per request:       0.194 [ms] (mean, across all concurrent requests)
  Transfer rate:          126625.50 [Kbytes/sec] received

  Connection Times (ms)
                min  mean[+/-sd] median   max
  Connect:        0    0   0.0      0       0
  Processing:     0    0   0.0      0       0
  Waiting:        0    0   0.0      0       0
  Total:          0    0   0.0      0       0

  Percentage of the requests served within a certain time (ms)
    50%      0
    66%      0
    75%      0
    80%      0
    90%      0
    95%      0
    98%      0
    99%      0
   100%      0 (longest request)
  ```

ACKs for top commit:
  achow101:
    ACK 03d49d0f25ab5660524d5ddd171de677a808b984
  theStack:
    re-ACK 03d49d0f25ab5660524d5ddd171de677a808b984
  tdb3:
    ACK 03d49d0f25ab5660524d5ddd171de677a808b984

Tree-SHA512: bbf3d78b8521f569430850ec4315a75711303547df1a3de213a4ad34c9700105e374e0a649352fd05f8e4badb5b59debd3720e1c5d392c5113d7816648f7fcaa

0 files changed, 0 insertions, 0 deletions