We have various locks to not archive the same site while another is in progress. This lock may not always work so we have another lock to not start archiving the same period/segment again while another archive is in progress (since Matomo 3.5 or so).

I don't know whether we have an Optimize Table lock but this could be actually quite helpful to prevent issues like this 👍

A workaround be to disable optimize table in Matomo by setting [General] enable_sql_optimize_queries = 0 in the config/config.php and then running for example the command ./console database:optimize-archive-tables for example monthly. This is I reckon better in general anyway as it shouldn't be needed to optimize tables all that often.

Hey @tsteur,
thank you for your fast answer!

Tonight it happened again:

Will disable optimize as advised by you and do it manually once a month - should be plenty enogh as you say! ;-)

Thank you, bye from sunny Austria
Andreas

ps) I'm a bit puzzled that both OPTIMIZE Queries are running the exact same amount of time - it seems 1 Job triggered them both the same time?!? (got definitely only 1 archive cron on server)

BTW: If the "has gone away" error persists check out #13685 (comment) and https://matomo.org/faq/troubleshooting/faq_183/

sorry for not getting back on this ... disabling OPTIMIZE immediately helped on my issue - everything working as expected again! ;-)
Problem was definitely 2 OPTIMIZE TABLE Threads which somehow locked each other out ...
(which also prevented MySQL Backups - as they were not able to lock the Tables which were already locked by OPTIMIZE)

thx, bye from Austria
Andreas

@futureweb I'll reopen the issue as we need to ideally add a lock there to not run this twice at the same time.

As I wrote on the FAQ/feedback page:

We need to fix Matomo1 so that it sets the wait_timeout per connection. Setting the server variable is an ugly ugly hack that does not 'play well with others'. Moving from mysqli to pdo/mysql makes it even worse, since old mysqi at least allowed auto-reconnection. (Forums tell me, however, this feature has been deprecated). Further, the pdo-mysql driver does not allow (or is not documented to allow) config/connection parameters to be set via the DSN. Perhaps it is allowed, but it is not documented. The solution can be found here: https://stackoverflow.com/a/21403360/3849157 . The wait_timeout setting should either be as given above (28800) or better yet, configurizable in config.ini.

@otheus
You could try adding the option here:

and report back if it changes anything. If it fixes the issue for you, it would be great if you could create a PR for this.

Thanks for contributing to this issue. As it has been a few months since the last activity and we believe this is likely not an issue anymore, we will now close this. If that's not the case, please do feel free to either reopen this issue or open a new one. We will gladly take a look again!