Run GC after every request, after closing the client socket and before attempting to accept more connections.
This shouldn’t hurt overall performance as long as the server cluster is at <50% CPU capacity, and improves the performance of most memory intensive requests. This serves to improve client-visible performance (possibly at the cost of overall performance).
We’ll call GC after each request is been written out to the socket, so the client never sees the extra GC hit it.
This middleware is only effective for applications that use a lot of memory, and will hurt simpler apps/endpoints that can process multiple requests before incurring GC.
This middleware is only designed to work with Unicorn, as it harms keepalive performance.
Example (in config.ru):
require 'unicorn/oob_gc' # GC ever two requests that hit /expensive/foo or /more_expensive/foo # in your app. By default, this will GC once every 5 requests # for all endpoints in your app use Unicorn::OobGC, 2, %r{\A/(?:expensive/foo|more_expensive/foo)}
# File lib/unicorn/oob_gc.rb, line 35 def call(env) status, headers, self.body = app.call(self.env = env) [ status, headers, self ] end
in Unicorn, this is closed after the client socket
# File lib/unicorn/oob_gc.rb, line 45 def close body.close if body.respond_to?(:close) if path =~ env['PATH_INFO'] && ((self.nr -= 1) <= 0) self.nr = interval self.body = nil env.clear GC.start end end
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