Ensure TCP_NODELAY is disabled by fixing namespacing #187

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merged 1 commit into from Feb 14, 2014

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nelgau commented Feb 14, 2014

While using bunny-1.1.0, we discovered an unacceptable latency for publishing messages with confirmation. Between a Bunny client and broker, both running Ubuntu Precise, this latency converges to 40ms for the case of many small messages. After some head-scratching, a packet capture revealed the true cause:

screen shot 2014-02-09 at 10 39 26 pm

Although both frames are sent in a tight loop, the client machine waits for an ACK before sending the payload. This suggests that Bunny isn't disabling Nagle's algorithm as a read through implies it ought to. After some poking, I discovered the bug:

     ::Socket.constants.include?(:TCP_NODELAY)  # => true
Bunny::Socket.constants.include?(:TCP_NODELAY)  # => false

By monkey-patching the implementation, I was able to achieve the desired result:

statsd airbnb

michaelklishin added a commit that referenced this pull request Feb 14, 2014

Merge pull request #187 from nelgau/really-disable-nodelay
Ensure TCP_NODELAY is disabled by fixing namespacing

@michaelklishin michaelklishin merged commit 7f57ef8 into ruby-amqp:master Feb 14, 2014

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michaelklishin added a commit to michaelklishin/sneakers that referenced this pull request Feb 15, 2014

Bump Bunny to 1.1.3+
[Significantly lower latency](ruby-amqp/bunny#187) for workloads that involve frequently sent small messages.

@michaelklishin michaelklishin referenced this pull request in jondot/sneakers Feb 15, 2014

Merged

Bump Bunny to 1.1.3+ #27

michaelklishin pushed a commit to gocardless/hutch that referenced this pull request Feb 15, 2014

Michael Klishin
Bunny 1.1.3+
[Lower latency](ruby-amqp/bunny#187), you see.
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