Issue #19412 has been updated by brodock (Gabriel Mazetto). when the pause happens it seems the socket is still kept alive, based on netstat: (there is a huge list of those): ``` tcp4 0 0 localhost.http-alt localhost.56818 TIME_WAIT tcp4 0 0 localhost.http-alt localhost.56819 TIME_WAIT tcp4 0 0 localhost.http-alt localhost.56820 TIME_WAIT tcp4 0 0 localhost.http-alt localhost.56821 TIME_WAIT tcp4 0 0 localhost.http-alt localhost.56822 TIME_WAIT tcp4 0 0 localhost.http-alt localhost.56823 TIME_WAIT tcp4 0 0 localhost.http-alt localhost.56825 TIME_WAIT tcp4 0 0 localhost.http-alt localhost.56824 TIME_WAIT tcp4 0 0 localhost.http-alt localhost.56826 TIME_WAIT tcp4 0 0 localhost.http-alt localhost.56827 TIME_WAIT tcp4 0 0 localhost.http-alt localhost.56828 TIME_WAIT tcp4 0 0 localhost.http-alt localhost.56829 TIME_WAIT tcp4 0 0 localhost.http-alt localhost.56830 TIME_WAIT tcp4 0 0 localhost.http-alt localhost.56831 TIME_WAIT tcp4 0 0 localhost.http-alt localhost.56832 TIME_WAIT tcp4 0 0 localhost.http-alt localhost.56833 TIME_WAIT tcp4 0 0 localhost.http-alt localhost.56834 TIME_WAIT tcp4 0 0 localhost.http-alt localhost.56835 TIME_WAIT ``` based on https://stackoverflow.com/questions/2187889/how-can-i-make-a-socket-close-im... it seems that there is a way to opt for socket reuse which would bypass this. It still weird that there is such a small limit on MacOS for how many of those we keep waiting before we can't accept anymore ---------------------------------------- Bug #19412: Socket starts queueing and not responding after a certain amount of requests https://bugs.ruby-lang.org/issues/19412#change-102431 * Author: brodock (Gabriel Mazetto) * Status: Open * Priority: Normal * ruby -v: ruby 3.2.1 (2023-02-08 revision 31819e82c8) [arm64-darwin22] * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- Here is a an example code: ```ruby require 'socket' PORT = 8080 BACKLOG = 50 LISTEN = '127.0.0.1' def handle_connection(connection, _addrinfo) request = connection.gets puts request connection.write "HTTP/1.1 200\r\n" connection.write "Content-Type: text/html\r\n" connection.write "\r\n" connection.write "Hello world! Current time is #{Time.now}" ensure connection.close end begin socket = Socket.new(:INET, :STREAM) socket.bind(Addrinfo.tcp(LISTEN, PORT)) socket.listen(BACKLOG) puts "Requested queue size: #{BACKLOG} bigger then limit: #{Socket::SOMAXCONN}" if BACKLOG > Socket::SOMAXCONN loop do listening, = IO.select([socket]) io, = listening connection, addrinfo = io.accept handle_connection(connection, addrinfo) end ensure socket.close end ``` This tries to simulate a TCP server that responds as if it was an HTTP server. The amount of requests it can sustain seems to depend on the OS. On a Linux machine running ubuntu 20.04 I get something around 7.6K to 7.8K until it stops responding. ``` $ uname -a Linux ... 5.17.5-x86_64-linode154 #1 SMP PREEMPT Mon May 2 15:07:22 EDT 2022 x86_64 x86_64 x86_64 GNU/Linux $ ab -n 20000 -c 50 http://127.0.0.1:8080/ This is ApacheBench, Version 2.3 <$Revision: 1843412 $> Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/ Licensed to The Apache Software Foundation, http://www.apache.org/ Benchmarking 127.0.0.1 (be patient) Completed 2000 requests Completed 4000 requests Completed 6000 requests apr_pollset_poll: The timeout specified has expired (70007) Total of 7883 requests completed ``` on MacOS Ventura I get around 16K: ``` $ uname -a Darwin ... 22.2.0 Darwin Kernel Version 22.2.0: Fri Nov 11 02:04:44 PST 2022; root:xnu-8792.61.2~4/RELEASE_ARM64_T8103 arm64 $ ab -n 20000 -c 50 http://127.0.0.1:8080/ This is ApacheBench, Version 2.3 <$Revision: 1901567 $> Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/ Licensed to The Apache Software Foundation, http://www.apache.org/ Benchmarking 127.0.0.1 (be patient) Completed 2000 requests Completed 4000 requests Completed 6000 requests Completed 8000 requests Completed 10000 requests Completed 12000 requests Completed 14000 requests Completed 16000 requests apr_socket_recv: Operation timed out (60) Total of 16375 requests completed ``` in both cases when that limit reaches, if I abort the program (CTRL-C) and try to run it again it takes a while until the port is released: ``` ... GET / HTTP/1.0 GET / HTTP/1.0 GET / HTTP/1.0 ^Csocketserver.rb:29:in `select': Interrupt from socketserver.rb:29:in `block in <main>' from socketserver.rb:28:in `loop' from socketserver.rb:28:in `<main>' $ ruby socketserver.rb socketserver.rb:23:in `bind': Address already in use - bind(2) for 127.0.0.1:8080 (Errno::EADDRINUSE) from socketserver.rb:23:in `<main>' ``` After killing the process it seems no process is holding the port: ``` lsof -wni tcp:8080 ``` Running the command above does not return anything (it does when the program is still running). I think we may be failing to release something when interacting with the Socket on syscalls/kernel level and we endup filling up some queue/buffer that eventually gets freed. ---Files-------------------------------- clipboard-202303161214-zhq7o.png (1.02 MB) clipboard-202303161214-7xx91.png (683 KB) clipboard-202303161215-5wjbo.png (1.02 MB) -- https://bugs.ruby-lang.org/