From 221340c4ebc1566677a29551bf4be7c05fc64b07 Mon Sep 17 00:00:00 2001 From: Eric Wong Date: Thu, 16 Apr 2020 09:24:57 +0000 Subject: prevent single listener from monopolizing a worker In setups with multiple listeners, it's possible for our greedy select(2)-avoidance optimization to get pinned on a single, busy listener and starve the other listener(s). Prevent starvation by retrying the select(2)-avoidance optimization if and only if all listeners were active. This should have no effect on the majority of deployments with only a single listener. Thanks to Stan Hu for reporting and testing. Reported-by: Stan Hu Tested-by: Stan Hu Link: https://yhbt.net/unicorn-public/CAMBWrQ=Yh42MPtzJCEO7XryVknDNetRMuA87irWfqVuLdJmiBQ@mail.gmail.com/ --- lib/unicorn/http_server.rb | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'lib/unicorn') diff --git a/lib/unicorn/http_server.rb b/lib/unicorn/http_server.rb index a52931a..45a2e97 100644 --- a/lib/unicorn/http_server.rb +++ b/lib/unicorn/http_server.rb @@ -686,6 +686,7 @@ class Unicorn::HttpServer trap(:USR1) { nr = -65536 } ready = readers.dup + nr_listeners = readers.size @after_worker_ready.call(self, worker) begin @@ -708,7 +709,7 @@ class Unicorn::HttpServer # we're probably reasonably busy, so avoid calling select() # and do a speculative non-blocking accept() on ready listeners # before we sleep again in select(). - unless nr == 0 + if nr == nr_listeners tmp = ready.dup redo end -- cgit v1.2.3-24-ge0c7