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From: Stan Hu <stanhu@gmail.com>
To: unicorn-public@yhbt.net
Subject: Sustained queuing on one listener can block requests from other listeners
Date: Tue, 14 Apr 2020 22:06:15 -0700
Message-ID: <CAMBWrQ=Yh42MPtzJCEO7XryVknDNetRMuA87irWfqVuLdJmiBQ@mail.gmail.com> (raw)

My unicorn.rb has two listeners:

listen "127.0.0.1:8080", :tcp_nopush => false
listen "/var/run/unicorn.socket", :backlog => 1024

We found that because of the greedy attempt to accept new connections
before calling select() in
https://github.com/defunkt/unicorn/blob/981f561a726bb4307d01e4a09a308edba8d69fe3/lib/unicorn/http_server.rb#L707-L714,
listeners on another socket stall out until the first listener is
drained. We would expect Unicorn to round-robin between the two
listeners, but that doesn't happen as long as there is work to be done
for the first listener. We've verified that deleting that `redo` block
fixes the problem.

What do you think about the various options?

1. Only running that redo block if there is one listener
2. Removing the redo block entirely

             reply	other threads:[~2020-04-15  5:06 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-15  5:06 Stan Hu [this message]
2020-04-15  5:26 ` Eric Wong
2020-04-16  5:46   ` Stan Hu
2020-04-16  6:59     ` Eric Wong
2020-04-16  7:24       ` Stan Hu
2020-04-16  9:24         ` [PATCH] prevent single listener from monopolizing a worker Eric Wong

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