Hi,
We've found a bug that is being triggered in clouddb hosts with an insane
statement that queries 6 tables across 694 different wikis. Which makes the
server reach the stack limit and produces a segfault. This is being tracked
at: https://phabricator.wikimedia.org/T420177 (which I restricted it as a
security task for now).
I've been working with Marko and Dave from MariaDB and they've already
provided a patch which I compiled and packaged yesterday night (but didn't
install yet as we needed to collect more info on the crashes)
However, until we are fully sure it is fixed, I am going to downgrade to
10.11.13 which is the latest stable version where this didn't happen - this
will be tracked at https://phabricator.wikimedia.org/T421826
We believe the bug was introduced at:
https://jira.mariadb.org/browse/MDEV-35816
If you want to follow the bug I sent to MariaDB which includes stack
traces, the involved tabels and the insane query, please check:
https://jira.mariadb.org/browse/MDEV-39209
*This only affects clouddb web hosts.*
If you've got any questions, let me know!
Manuel.