Issue PASSENGER Returning HTTP 503 due to: Request queue full (configured max. size: 100)

[Luiz_Gustavo]

Server operating system version

Ubuntu 24.04

Plesk version and microupdate number

18.0.65 #2

Hello,

My passenger is showing eventyally this error:
age/Cor/Con/CheckoutSession.cpp:266 ]: [Client 7-475704] Returning HTTP 503 due to: Request queue full (configured max. size: 100)

Where I can increase the Request Queue for passenger?




Thanks,
Luiz

 

[Vladimir C.]

Hello! Please check passenger configuration files on your server for corresponding directive:

Nginx:
passenger_max_requests
/etc/nginx/modules.available.d/phusion-passenger.conf
Configuration reference - Passenger + Nginx - Passenger Library

Apache:
PassengerMaxRequests
/etc/apache2/mods-available/passenger.conf

Configuration reference - Passenger + Apache - Passenger Library

Please note that default value PassengerMaxRequests 0 means that there is no maximum. I've installed Passenger on test Ubuntu 24 server with Plesk 18.0.65 and such directives not present in config so it's probably customized on your server.

 

[Luiz_Gustavo]

Hello Vladimir,

Thank you for your response.


My server uses a default Plesk installation. It runs a Node.js application with all default settings, including NGINX.

I have made a few changes: I increased the ulimit, set worker_processes to 8, and worker_connections to 4096. However, I haven’t made any changes to the Passenger configuration.

I also tried adding passenger_max_request_queue_size 250; in the NGINX additional directives.
Despite this, the passenger-status command does not show anything about the queue. Is there a way to verify the effective configuration?


Version : 6.0.23
Date : 2024-12-10 09:02:48 -0300
Instance: eRLz9iJe (nginx/1.26.2 Phusion_Passenger/6.0.23)

----------- General information -----------
Max pool size : 6
App groups : 1
Processes : 1
Requests in top-level queue : 0

----------- Application groups -----------
/var/www/vhosts/superplacar.com.br/ (production):
App root: /var/www/vhosts/xxxxxxxxxxxxx/
Requests in queue: 0
* PID: 1266861 Sessions: 73 Processed: 556 Uptime: 2m 43s
CPU: 0% Memory : 20M Last used: 3s ago

 

[Vladimir C.]

> Is there a way to verify the effective configuration?
I did not find specific command to verify this option. In general, it's required to add option to config and restart nginx/apache to take it into effect.

Additionally, it might be issue not related to the passenger configuration, because if in request queue 100 pending requests it’s likely means that requests are really not processed (f.e. worker stucks).