development performance sysadmin

docker proxy image download

Docker doesn’t like me for some reason, and I often get really bad download speeds from my home IP address. One crude fix, is use an external server I can access as a SOCKS proxy. To do so, edit / create /etc/systemd/system/docker.service.d/http-proxy.conf and put in it : [Service] Environment=”HTTP_PROXY=socks5://localhost:8888″ Then, restart/reload systemd ( systemctl daemon-reload […]

debian linux mysql performance

MySQL Max_connections stuck on 214 ?

I found MySQL was being annoying earlier and not ‘accepting’ my max_connections = 450 directive on a Debian Wheezy install, and being seemingly stuck on having 214 connections….


FTTC limited by wifi….

Compare : (Speedtest over ethernet) with (Speedtest over wifi). Now how do I go about getting Sky to giving me a wifi router box thing that does 802.11n or whatever?

mysql performance

MySQL update/write query analysis (query profiling)

Do you have a slow MySQL update/insert/delete query? Obviously, for ‘SELECT’ queries you can prepend the query with “EXPLAIN ” – however that doesn’t work for the other query types (UPDATE/INSERT/DELETE). So, one solution which may explain why the query is slow is to turn on MySQL’s profiling functionality, like in the following example :

development performance php

Zend_Cache – automatic cache cleaning can be bad, mmkay?

$customer uses Zend_Cache in their codebase – and I noticed that every so often a page request would take ~5 seeconds (for no apparent reason), while normally they take < 1 second … Some rummaging and profiling with xdebug showed that some requests looked like : Note how there are 25,000 or so calls for […]

linux performance

Checking varnish configuration syntax

If you’ve updated your varnish server’s configuration, there doesn’t seem to be an equivalent of ‘apachectl configtest’ for it, but you can do : varnishd -C -f /etc/varnish/default.vcl If everything is correct, varnish will then dump out the generated configuration. Otherwise you’ll get an error message pointing you to a specific line number.