max_children issue

[skybound]

Been having performance issues in the last few weeks and after contacting our hosting co, they came back with the following:

After reviewing the error logs for your domain, we have confirmed that your website has encountered multiple occurrences of max_children errors. Here is an excerpt from the logs for your reference:
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[31-May-2023 12:00:48] WARNING: [pool hetz-avcoma-php81] server reached max_children setting (20), consider raising it
[31-May-2023 12:06:15] WARNING: [pool hetz-avcoma-php81] server reached max_children setting (20), consider raising it
[31-May-2023 12:36:48] WARNING: [pool hetz-avcoma-php81] server reached max_children setting (20), consider raising it
[31-May-2023 12:41:52] WARNING: [pool hetz-avcoma-php81] server reached max_children setting (20), consider raising it
[31-May-2023 12:57:31] WARNING: [pool hetz-avcoma-php81] server reached max_children setting (20), consider raising it


This situation indicates that the PHP processes on your website are taking too long to close, causing all available slots to be utilized. Once the maximum number of slots is reached, the website becomes unable to load or open any additional PHP connections or website queries until one of the existing PHP connections is closed. Consequently, MySQL connections are also affected, as no further connections can be established. This explains why you are encountering this error on your website.

We recommend contacting your web developer and providing them with the above information. They should ensure that your website is optimized to prevent long-running database queries from exhausting the available connection slots in the future. Additionally, they should ensure that queries are terminated promptly after completion. Taking these measures will help resolve the issue at hand.

On version 3.3.10. All extension are on latest version.

Where do I start to troubleshoot this?

[AmigoJack]

consider raising it

Just do that. Given how big your RAM is and how much CPU cores you have it might be a bigger number, see https://serverfault.com/questions/93943 ... ren-tuning - otherwise just experiment by increasing it to 25.

They should ensure that your website is optimized to prevent long-running database queries from exhausting the available connection slots in the future.

phpBB doesn't ensure this. Keep an eye on database statistics, such as slow queries. Adding indexes might help increasing performance, but comes at the cost of maintenance and addition storage space needed.

they should ensure that queries are terminated promptly after completion. Taking these measures will help resolve the issue at hand.

phpBB ensures this already. However, your first action should be to disable all extensions and then one by one enable them again, checking inbetween if you can identify the one which might be programmed too sloppy.

[skybound]

Thanks AmigoJack.

How many seconds would be regarded as a slow query? Current setting is 10 and the log is empty.

[AmigoJack]

You have to define that for yourself: is waiting 10 seconds for a requested page too long? It also depends on the tasks themselves: if something needs 45 seconds but is only needed once a month then it's okay to be slow.