feat: Celery worker concurrency setting

This allows the user to configure how many Celery workers are spawned
independently of how many CPUs there are in the system. The default is
to spawn as many workers as there are CPUs, which in some cases can
consume too many resources.

(The setting should be particularly useful to people running Tutor for
development on Linux machines, where reducing the concurrency to "1" can
reduce RAM usage significantly.)

Author: arbrandes

changelog.d/20240229_171657_arbrandes_celery_concurrency.md

@@ -0,0 +1 @@
+- [Feature] Allow the user to configure Celery worker concurrency. (by @arbrandes)

docs/configuration.rst

@@ -180,6 +180,17 @@ This configuration parameter sets the name of the MySQL Database to be used by t
 
 This configuration parameter sets the username associated with the MySQL Database.
 
+Celery workers
+~~~~~~~~~~~~~~
+
+- ``LMS_WORKER_CONCURRENCY`` (default: ``"0"``)
+
+This sets the number of LMS celery workers at startup.  Defaults to the number of CPUs detected on the system (represented by "0").
+
+- ``CMS_WORKER_CONCURRENCY`` (default: ``"0"``)
+
+This sets the number of LMS celery workers at startup.  Defaults to the number of CPUs detected on the system (represented by "0").
+
 CMS OAUTH2 SSO
 ~~~~~~~~~~~~~~
 

tutor/templates/config/defaults.yml

@@ -9,6 +9,7 @@ CADDY_HTTP_PORT: 80
 CMS_HOST: "studio.{{ LMS_HOST }}"
 CMS_OAUTH2_KEY_SSO: "cms-sso"
 CMS_OAUTH2_KEY_SSO_DEV: "cms-sso-dev"
+CMS_WORKER_CONCURRENCY: 0
 CONTACT_EMAIL: "contact@{{ LMS_HOST }}"
 DEV_PROJECT_NAME: "{{ TUTOR_APP }}_dev"
 DOCKER_COMPOSE_VERSION: "3.7"
@@ -42,6 +43,7 @@ JWT_COMMON_SECRET_KEY: "{{ OPENEDX_SECRET_KEY }}"
 K8S_NAMESPACE: "openedx"
 LANGUAGE_CODE: "en"
 LMS_HOST: "www.myopenedx.com"
+LMS_WORKER_CONCURRENCY: 0
 LOCAL_PROJECT_NAME: "{{ TUTOR_APP }}_local"
 MONGODB_AUTH_MECHANISM: ""
 MONGODB_AUTH_SOURCE: "admin"

tutor/templates/k8s/deployments.yml

@@ -141,7 +141,7 @@ spec:
       containers:
         - name: cms-worker
           image: {{ DOCKER_IMAGE_OPENEDX }}
-          args: ["celery", "--app=cms.celery", "worker", "--loglevel=info", "--hostname=edx.cms.core.default.%%h", "--max-tasks-per-child", "100", "--exclude-queues=edx.lms.core.default"]
+          args: ["celery", "--app=cms.celery", "worker", "--loglevel=info", "--hostname=edx.cms.core.default.%%h", "--concurrency={{ CMS_WORKER_CONCURRENCY }}", "--max-tasks-per-child", "100", "--exclude-queues=edx.lms.core.default"]
           env:
           - name: SERVICE_VARIANT
             value: cms
@@ -250,7 +250,7 @@ spec:
       containers:
         - name: lms-worker
           image: {{ DOCKER_IMAGE_OPENEDX }}
-          args: ["celery", "--app=lms.celery", "worker", "--loglevel=info", "--hostname=edx.lms.core.default.%%h", "--max-tasks-per-child=100", "--exclude-queues=edx.cms.core.default"]
+          args: ["celery", "--app=lms.celery", "worker", "--loglevel=info", "--hostname=edx.lms.core.default.%%h", "--concurrency={{ LMS_WORKER_CONCURRENCY }}", "--max-tasks-per-child=100", "--exclude-queues=edx.cms.core.default"]
           env:
           - name: SERVICE_VARIANT
             value: lms

tutor/templates/local/docker-compose.yml

@@ -158,7 +158,7 @@ services:
     environment:
       SERVICE_VARIANT: lms
       DJANGO_SETTINGS_MODULE: lms.envs.tutor.production
-    command: celery --app=lms.celery worker --loglevel=info --hostname=edx.lms.core.default.%%h --max-tasks-per-child=100 --exclude-queues=edx.cms.core.default
+    command: celery --app=lms.celery worker --loglevel=info --hostname=edx.lms.core.default.%%h --concurrency={{ LMS_WORKER_CONCURRENCY }} --max-tasks-per-child=100 --exclude-queues=edx.cms.core.default
     restart: unless-stopped
     volumes:
       - ../apps/openedx/settings/lms:/openedx/edx-platform/lms/envs/tutor:ro
@@ -177,7 +177,7 @@ services:
     environment:
       SERVICE_VARIANT: cms
       DJANGO_SETTINGS_MODULE: cms.envs.tutor.production
-    command: celery --app=cms.celery worker --loglevel=info --hostname=edx.cms.core.default.%%h --max-tasks-per-child 100 --exclude-queues=edx.lms.core.default
+    command: celery --app=cms.celery worker --loglevel=info --hostname=edx.cms.core.default.%%h --concurrency={{ CMS_WORKER_CONCURRENCY }} --max-tasks-per-child 100 --exclude-queues=edx.lms.core.default
     restart: unless-stopped
     volumes:
       - ../apps/openedx/settings/lms:/openedx/edx-platform/lms/envs/tutor:ro