Configure Gunicorn Workers

|RCE| comes with Gunicorn which is a Python WSGI HTTP Server for UNIX.

To improve |RCE| performance you can increase the number of Gunicorn workers. This allows to handle more connections concurrently, and provide better responsiveness and performance.

By default during installation |RCC| tries to detect how many CPUs are available in the system, and set the number workers based on that information. However sometimes it's better to manually set the number of workers.

To do this, use the following steps:

1. Open the :file:`home/{user}/.rccontrol/{instance-id}/rhodecode.ini` file.
2. In the [server:main] section, change the number of Gunicorn workers using the following default formula (2*Cores) + 1. We however not recommend using more than 8-12 workers per server. It's better to start using the :ref:`scale-horizontal-cluster` in case that performance with 8-12 workers is not enough.

use = egg:gunicorn#main
## Sets the number of process workers. You must set `instance_id = *`
## when this option is set to more than one worker, recommended
## value is (2 * NUMBER_OF_CPUS + 1), eg 2CPU = 5 workers
## The `instance_id = *` must be set in the [app:main] section below
workers = 4
## process name
proc_name = rhodecode
## type of worker class, one of sync, gevent
## recommended for bigger setup is using of of other than sync one
worker_class = sync
## The maximum number of simultaneous clients. Valid only for Gevent
#worker_connections = 10
## max number of requests that worker will handle before being gracefully
## restarted, could prevent memory leaks
max_requests = 1000
max_requests_jitter = 30
## amount of time a worker can spend with handling a request tuning-change-lfs-dir.before it
## gets killed and restarted. Set to 6hrs
timeout = 21600

3. In the [app:main] section, set the instance_id property to *.

# In the [app:main] section
[app:main]
# You must set `instance_id = *`
instance_id = *

4. Change the VCSServer workers too. Open the :file:`home/{user}/.rccontrol/{instance-id}/vcsserver.ini` file.
5. In the [server:main] section, increase the number of Gunicorn workers using the following formula (2*Cores) + 1.

## run with gunicorn --log-config vcsserver.ini --paste vcsserver.ini
use = egg:gunicorn#main
## Sets the number of process workers. Recommended
## value is (2 * NUMBER_OF_CPUS + 1), eg 2CPU = 5 workers
workers = 4
## process name
proc_name = rhodecode_vcsserver
## type of worker class, currently `sync` is the only option allowed.
worker_class = sync
## The maximum number of simultaneous clients. Valid only for Gevent
#worker_connections = 10
## max number of requests that worker will handle before being gracefully
## restarted, could prevent memory leaks
max_requests = 1000
max_requests_jitter = 30
## amount of time a worker can spend with handling a request before it
## gets killed and restarted. Set to 6hrs
timeout = 21600

6. Save your changes.
7. Restart your |RCE| instances, using the following command:

$ rccontrol restart '*'

Gunicorn Gevent Backend

Gevent is an asynchronous worker type for Gunicorn. It allows accepting multiple connections on a single Gunicorn worker. This means you can handle 100s of concurrent clones, or API calls using just few workers. A setting called worker_connections defines on how many connections each worker can handle using Gevent.

To enable Gevent on |RCE| do the following:

1. Open the :file:`home/{user}/.rccontrol/{instance-id}/rhodecode.ini` file.
2. In the [server:main] section, change worker_class for Gunicorn.

## type of worker class, one of sync, gevent
## recommended for bigger setup is using of of other than sync one
worker_class = gevent
## The maximum number of simultaneous clients. Valid only for Gevent
worker_connections = 30