Too many connections error with Laravel 5.4 and Mariadb

Question

I have recently upgraded my laravel app from 5.1 to 5.4. My server is now on PHP 7 and Maria db 10.1.22. Now I am getting a really weird error. Sometimes, I would just try to refresh my browser and PHPMyAdmin would display #1040 - Too many connections . Other times I would click on a new link on my app and then would get this same error. I did some research on the internet and executed the command below:

show variables like 'max_connections`

The above command gave 100. Which I then increase to 500.

But now I still get the error. This is weird to me because I have oracle mysql 5.6 installed on another server and max_connections is 151 and for over a year and a half I have not experienced this error.

When I run the command show processlist , I get the result below and this keeps increasing. is this normal?

What could be the issue with Mariadb and how can I fix it.

Answer 1

I am not sure if you guys found the solution or not but I was facing the same problem as well and found the solution. As we upgraded our laravel application from 5.2 - 5.4, we missed something important. php artisan queue:work has been upgraded as well.

In laravel 5.2, when we execute queue:work. It just process one job at a time but in laravel 5.4 queue:work creates a connection for your queue and keeps it connected. So if you have queue:work in your cron to run every minute it will create a new connection every minute and that is why we get the error of too many connections.

I did not find this information on laravel 5.4 documentation. I was going through php artisan to see the description of queue:work and found out that the description is changed.

This is description in laravel 5.2:

queue:work >>>> Process the next job on a queue

This is description in laravel 5.4

queue:work >>>> Start processing jobs on the queue as a daemon

As you can see the difference in what they are meant to do.

I hope that this helps you out.

Thanks.

Answer 2

Maybe it is a silly observation, but did you use DB::disconnect('foo') to closes the conenctions of your db?

Anyway, the db closes automatically, so the problem may be somewhere else, did you try monitoring?

A very powerful tool to monitor MySQL is innotop . You can find it here:

https://github.com/innotop/innotop

Check this

Answer 3

What webserver are you using. If Apache, then what is the setting of MaxRequestWorkers (formerly called MaxClients ) for it? Generally it should be no more than about 20.

If that is set to more than max_connections , that would explain what you are seeing.