[support] Druapal server fatal error: "MySQL server has gone away", but DB server is still up & accessible. Help troubleshooting?

[grantksupport at operamail.com]

SOLVED.

It's a bug in MariaDB.

https://mariadb.atlassian.net/browse/MDEV-6340?focusedCommentId=52089&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-52089

It mainfests when GCC 4.9 is used.

The issue's ID'd at

 "Operational Notification -- Changes in gcc Code Optimization Can Cause
 a Crash in BIND"
  https://kb.isc.org/article/AA-01167

The workaround is to add

 "CFLAGS=-fno-delete-null-pointer-checks" 

to gcc compile options

Here, with MariaDB 10.0.12 / ReleaseBuild built with GCC 4.9 +
CFLAGS=-fno-delete-null-pointer-checks, drush site-install of Drupal
7.28 exec with no errors, and `drush *` works on existing site with no
errors.