The implementation of the check_client_connection causing an early write is
ineffective when not performed on loopback. In my testing, when on non-loopback,
such as another host, we only see a 10-20% rejection rate with TCP_NODELAY of
clients that are closed. This means 90-80% of responses in this case are
rendered in vain.
This patch uses getosockopt(2) with TCP_INFO on Linux to read the socket state.
If the socket is in a state where it doesn't take a response, we'll abort the
request with a similar error as to what write(2) would give us on a closed
socket in case of an error.
In my testing, this has a 100% rejection rate. This testing was conducted with
the following script:
100.times do |i|
client = TCPSocket.new("some-unicorn", 20_000)
client.write("GET /collections/#{rand(10000)}
HTTP/1.1\r\nHost:walrusser.myshopify.com\r\n\r\n")
client.close
end
---
lib/unicorn/http_request.rb | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/lib/unicorn/http_request.rb b/lib/unicorn/http_request.rb
index 0c1f9bb..b4c95fc 100644
--- a/lib/unicorn/http_request.rb
+++ b/lib/unicorn/http_request.rb
@@ -31,6 +31,9 @@ class Unicorn::HttpParser
@@input_class = Unicorn::TeeInput
@@check_client_connection = false
+ # TCP_TIME_WAIT: 6, TCP_CLOSE: 7, TCP_CLOSE_WAIT: 8, TCP_LAST_ACK: 9
+ IGNORED_CHECK_CLIENT_SOCKET_STATES = (6..9)
+
def self.input_class
@@input_class
end
@@ -83,10 +86,18 @@ def read(socket)
false until add_parse(socket.kgio_read!(16384))
end
- # detect if the socket is valid by writing a partial response:
- if @@check_client_connection && headers?
- self.response_start_sent = true
- HTTP_RESPONSE_START.each { |c| socket.write(c) }
+ # detect if the socket is valid by checking client connection.
+ if @@check_client_connection
+ if defined?(Raindrops::TCP_Info)
+ tcp_info = Raindrops::TCP_Info.new(socket)
+ if IGNORED_CHECK_CLIENT_SOCKET_STATES.cover?(tcp_info.state)
+ socket.close
+ raise Errno::EPIPE
+ end
+ elsif headers?
+ self.response_start_sent = true
+ HTTP_RESPONSE_START.each { |c| socket.write(c) }
+ end
end
e['rack.input'] = 0 == content_length ?
--
2.11.0
