Rails to DB TCP Reset issue

Phusion Passenger version 3.0.18
nginx version: nginx/1.2.4
ruby 1.8.7 (2011-06-30 patchlevel 352) [x86_64-linux]
rails (3.0.20)

MULTIPLE TCP RESETS sent

I usually see 20-25 database connections from my
ruby/rails//passenger/nginx server to my database server. Pool is set to
25. Passenger is limited to 20

I am seeing lots of TCP Resets and dropped mysql connections. I run the
DB
on port 3312…and using tcpdump I can see the db sends a [S.] SYN-ACK
but
the rails server responds with a [R] RESET immediately.
tcptrack on port 3312 shows 20-25 connections then all of a sudden it
jumps
to 300-600 connections but the majority are RESET (s) Any idea why rails
would be killing off so many DB connections (more then are even
established)

-dave webster

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yyy.yyy.yyy.yyy:49257 xxx.xxx.xxx.xxx:3312 ESTABLISHED 1s 7
KB/s
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On Wednesday, January 22, 2014 8:52:28 PM UTC+1, David Webster wrote:

  1. Passenger is limited to 20

I am seeing lots of TCP Resets and dropped mysql connections. I run the DB
on port 3312…and using tcpdump I can see the db sends a [S.] SYN-ACK but
the rails server responds with a [R] RESET immediately.
tcptrack on port 3312 shows 20-25 connections then all of a sudden it
jumps to 300-600 connections but the majority are RESET (s) Any idea why
rails would be killing off so many DB connections (more then are even
established)

Unless funny business is happening I wouldn’t thought this mattered but
there is very little point in setting the pool to 25 since each
passenger
instance only processes one request at a time. The default of 5 is
usually
ample. I wouldn’t have thought this mattered though - the limit of 25
would
normally never kick in in the first place.

Fred

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