Hi, Just getting back to you. Sorry about the delay.
This behaviour was caused by a custom patch in a module. The patch was ending the requests without finalizing them, leaking connections. Eventually Nginx just exploded =) Nothing like production workload to stress things out. Thanks a lot. On Sun, Dec 20, 2015 at 11:04 AM, Valentin V. Bartenev <[email protected]> wrote: > On Friday 18 December 2015 15:55:47 Marcelo MD wrote: > > Hi, > > > > Recently we added a 'thread_pool' directive to our main configuration. A > > few hours later we saw a huge increase in the connections_writing stat as > > reported by stub_status module. This number reached +- 3800 and is stuck > > there since. The server in question is operating normally, but this is > very > > strange. > > > > Any hints on what this could be? > > > > > > Some info: > > > > - Here is a graph of the stats reported, for a server with thread_pool > and > > another without: http://imgur.com/a/lF2EL > > > > - I don`t have older data anymore, but the jump from <100 to +- 3800 > > connections_writing happened in two sharp jumps. The first one following > a > > reload; > > > > - The machines' hardware and software are identical except for the > > thread_pool directive in their nginx.conf. They live in two different > data > > centers; > > > > - Both machines are performing normally. Nothing unusual in CPU or RAM > > usage. Nginx performance is about the same. > > > > - Reloading Nginx with 'nginx -s reload' does nothing. Restarting the > > process brings connections_writing down. > [..] > > As I understand from your message everything works well. You should also > check the error_log, if it doesn't have anything suspicious then there is > nothing to worry about. > > The increased number of writing connections can be explained by increased > concurrency. Now nginx processing cycle doesn't block on disk and can > accept more connections at the same time. All the connections that were > waiting in listen socket before are waiting now in thread pool. > > wbr, Valentin V. Bartenev > > _______________________________________________ > nginx mailing list > [email protected] > http://mailman.nginx.org/mailman/listinfo/nginx > -- Marcelo Mallmann Dias
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