Php-fpm setting needs validated against pm.min_spare_servers and pm.max_spare_servers

Virtualmin
1

VirtualMin 7.1 gpl
RedHat 7

trying to be frugal, on my new test 7.1 system I adjusted the PHP FCGId sub-processes item on the PHP Options panel to be 4. Then I was in for a surprise – the php-fpm process died – that is, during the shutdown/restart action, it did shut down but then failed to start back up !!

It says in the logfile /var/log/php-fpm/error.log

ALERT: [pool 155655479617843] pm.min_spare_servers(1) and pm.max_spare_servers(5) cannot be greater than pm.max_children(4)

I see in php-lib.pl, in the routine create_php_fpm_pool that some values are hardcoded:

                   "pm.start_servers = 1",
                   "pm.min_spare_servers = 1",
                   "pm.max_spare_servers = 5",

I am not sure of the correct place to put a sanity check, but I respectfully suggest one is needed … to avoid the issue I ran into today.

At times at the SSH command line when I am tweaking things by hand, I will run

php-fpm -t

before doing a reload/restart, but I don’t know if that can be generalized or automated.

Verne

2

@verne - go find your php pool conf files - perhaps in

/etc/php/7.4/fpm/pool.d

replace 7.4 with whatever version you are using and you need to either set pm.max_spare_servers = 4, or set pm.max_children = 5.

Virtualmin may set some other original values - when I create a Virtual Server, I always go to it’s pool conf file and set them to what I want\need.

HIH

Dibs

3

Thanks, good point !! But I worry that its a bad design when a minor change via the GUI can cripple my system.

Verne

4

@verne - there may well be somewhere in the GUI that you can set whatever “baseline” values you want, but I just set them manually in the files and the GUI doesn’t overwrite them - so the chance of the GUI crippling your system is NIL.

Dibs

5

I see patch bf66dca to php-lib.pl on github back on July 29 addresses this issue !!!

THANKS GUYS !!

6

Yes, you are right – it was a bug and I think I have already fixed that. Where exactly did you make the change? If that was PHP Options page, it will be fixed in Virtualmin 7.2 release.

7

Yes, most probably that’s the one.

8

I installed virtualmin 7.2.gpl-1 on Ubuntu22.04(aws ver) yesterday, but I came to see the same problem.

I made a first domain to use php8.1-fpm, and php8.1service stops.

In /etc/php/8.1/fpm/pool.d/www.conf, it is set as below.

pm.max_children = 5
pm.start_servers = 2
pm.min_spare_servers = 1
pm.max_spare_servers = 3

But in /etc/php/8.1/fpm/pool.d/16651099103631.conf, made by virtualmin when create first domain , it is set below

pm.max_children = 3
pm.start_servers = 1
pm.min_spare_servers = 1
pm.max_spare_servers = 5

So stop with the error below.

pm.min_spare_servers(1) and pm.max_spare_servers(5) cannot be greater than pm.max_children(3)

Is there some more setting need to use the fpm?

10

Bring up VirtualMin on port 10000 in a browser. Log in. Choose your domain in the VirtualMin pulldown menu.

Expand the Server Configuration item. Then choose PHP Options.

On that panel, when FPM is chosen (if you have a choice), there is the item

PHP FCGId sub-processes

adjust that to be 5 or more (or whatever you see for pm.max_spare_servers) – this value is used for pm.max_children for this domain. Then start php-fpm for 8.1 back up again. You will have to do this by hand for each new domain.

I have no idea how to fix the root cause (well, if you are very brave, you can edit the VirtualMin PL scripts/files :slight_smile: – that is, how to make VirtualMin handle this issue). But you can adjust your Server Template for all future domains … in VirtualMin, expand the lower menu section System Settings. Then choose Server Templates.

Once there, choose Default Settings, or make a new custom one for yourself. Once you are viewing a Server Template, use the pulldown to choose PHP Options. Once on that panel, adjust

Default FCGId PHP sub-processes

to be 5 or more (or whatever you see for pm.max_spare_servers) – this value is used for pm.max_children for all new domains.

11

Next, upcoming Virtualmin 7.2.1 (or 7.3) will have pm.max_spare_servers dynamically set.

12

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