Connection "delayed" attempts
Posted by: Derek Meyer
Date: April 29, 2016 08:16AM

To All:

I have one that has stumped me and I have been reading the documents, to date I have not figured out what to adjust

I have a mixed use server that is in a master/master setup with a couple of slaves. Average connections per second is around 50 with bursts of up to 100. Most of the query's are very fast and appear to be optimized properly (or as well as I can get them) Max connections is 1000 and my "normal" active sessions is about 150. The Database is mixed Myisam and Innodb and about 80/20 writes and sometimes 20/80 reads (it is a monitoring tool and will depend on the amount of alerts as it has some downstream apps hooked to it)

I have a VERY strange issue that I am just plain stumped on when either of the following happens even though I am not near my max connections the server stops taking new connections for about 30 minutes

process #1 purge binary logs until xxx
process #2 pt-archiver that purges some stale data (just purge and not archive)

Most of the processes that connect to the DB are written in perl/php

I have increased the thread_cache and max connections quite a bit and the server is not spiking in memory/io/cpu (Disk IO goes up some but not a ton)

One interesting item that I have is I have recently upgraded to MonYog for server monitoring I get the following

Sampling timeframe: All Time/Current
Name Currently running threads
Group Current Connections
Type Critical
Threshold 25
Value 33

I can not seem to find the correct item in order to resolve this.. the connection "delay" lasts about 30 seconds (most of our scripts give up after 5 seconds of not being able to connect)

**Note I am sure it is not the programs having intermittent issues as I can duplicate it on demand with doing either one of the above commands


any suggestions?

Thank you

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Connection "delayed" attempts
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