[Enswitch-announce] Important code update for those who have experienced MySQL deadlocks

[Alistair Cunningham]

All,

As some of you may know, earlier this year we made a code change to 
Enswitch 3.9 and later to do some MySQL transactions in "read committed" 
mode. This was to prevent MySQL deadlocks. It turns out that this change 
is causing problems for those upgrading from 3.8 and earlier because it 
requires MySQL configuration changes to use. Such are the dangers of 
back-porting code to stable versions, and I apologise for the upgrading 
problems caused. To prevent problems for future upgraders, we're about 
to commit code changes to:

1. Disable read committed mode by default, i.e. restore the behaviour 
that existed at the start of the year.

2. Provide a new field in /etc/enswitch/databases.conf to enable read 
committed mode if needed.

If you haven't been experiencing MySQL deadlocks, and therefore don't 
need read committed mode, you can ignore this change.

If you have been experiencing MySQL deadlocks that the read committed 
change has fixed, please open a support ticket before you next update to 
the latest fixes or before you next upgrade Enswitch. Support staff can 
then show you what configuration changes are needed in databases.conf 
(basically, add a ", 1" to the end of each line). It's very important 
that you do this, else the deadlocks are likely to return.

-- 
Alistair Cunningham
+1 888 468 3111
+44 20 799 39 799
http://integrics.com/