Class: Net::HTTPNoDelay

Inherits:
HTTP
  • Object
show all
Defined in:
lib/verm/http_no_delay.rb

Overview

This class can be used as a workaround for Net::HTTP’s lack of TCP_CORK/TCP_NOPUSH in sending requests. When using a Linux client and a Linux server we observe awful latency POSTing files on reused HTTP connections because Post class writes one block of data for the header and separate block(s) for the body. If the body is not sufficiently large to fill another packet itself, the Nagle algorithm will have Linux (by default) wait for the ACK from the first packet to be received back; unfortunately, this won’t be sent immediately because of the Delayed ACK algorithm. As a result we typically observe 40ms of extra latency when POSTing small files. This class disables the Nagle algorithm to work around that. It’s not an ideal fix because we would rather combine the write for the header with the write for the first N bytes of the body, but it should give performance better than the standard Ruby implementation in all cases because Nagle is of no benefit when queuing large blocks only to the OS (as both the streaming and non-streaming variants of the body write calls will do), and the way that Ruby is writing the header separately to the body means there will always be at least two packets anyway.

Instance Method Summary collapse

Instance Method Details

#on_connect ⇒ Object 



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# File 'lib/verm/http_no_delay.rb', line 17

def on_connect()
  @socket.io.setsockopt(Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1)
end