feat(mediasoup: add configurable nice for media type workers

Similar in spirit to 66d443d, but
targeted at mediasoup workers. The idea here is allow prioritization of
workers by media type (eg audio should be higher priority than
main/content workers).

Also adds a couple of fixes to priority config parsing.

config/custom-environment-variables.yml

@@ -204,6 +204,16 @@ mediasoup:
     content:
       __name: MS_CONTENT_WORKERS
       __format: yaml
+  workerPriorities:
+    audio:
+      __name: MS_AUDIO_PRIO
+      __format: yaml
+    main:
+      __name: MS_MAIN_PRIO
+      __format: yaml
+    content:
+      __name: MS_CONTENT_PRIO
+      __format: yaml
   worker:
     rtcMinPort:
       __name: MS_RTC_MIN

config/default.example.yml

@@ -312,6 +312,18 @@ mediasoup:
     audio: 0
     main: 0
     content: 0
+  # mediasoup.workerPriorities:
+  #   audio: <os.constants.priority> | [19,-20]
+  #   main: <os.constants.priority> | [19,-20]
+  #   content: <os.constants.priority> | [19,-20]
+  #
+  #   * Sets the NICE level for each worker type. The app needs the correct user
+  #   caps to be effective
+  #
+  #workerPriorities:
+  #  audio: PRIORITY_HIGH
+  #  main: PRIORITY_NORMAL
+  #  content: PRIORITY_LOW
   worker:
     # "debug", "warn", "error", "none"
     logLevel: "error"

lib/common/utils.js

@@ -29,7 +29,9 @@ const addBwToSpecContentType = (spec, bitrate) => {
 
 const _getNormalizedPriority = (prio) => {
   if (typeof prio === 'number') return prio;
-  if (typeof prio === 'string' && os.constants.priority[prio]) return os.constants.priority[prio];
+  if (typeof prio === 'string' && typeof os.constants.priority[prio] === 'number') {
+    return os.constants.priority[prio];
+  }
 
   throw new TypeError('Invalid priority')
 }

lib/main/process-wrapper.js

@@ -81,7 +81,7 @@ module.exports = class ProcessWrapper {
     this.process.on('message', this._onMessage);
     this.process.on('error', this.onError.bind(this));
 
-    if (this.priority) setProcessPriority(this.process.pid, this.priority);
+    if (this.priority != null) setProcessPriority(this.process.pid, this.priority);
 
     PrometheusAgent.set(SFUM_NAMES.MODULE_STATUS, 1, {
       module: this.name,

lib/mcs-core/lib/adapters/mediasoup/configs.js

@@ -12,6 +12,7 @@ const {
     [C.MEDIA_PROFILE.CONTENT]: 0,
     [C.MEDIA_PROFILE.AUDIO]: 0,
   },
+  workerPriorities: WORKER_PRIORITIES = {},
   promExportWorkerResourceUsage: WORKER_EXPORT_RESOURCE_USAGE,
   worker: WORKER_SETTINGS,
   router: ROUTER_SETTINGS = { mediaCodecs: mediasoup.getSupportedRtpCapabilities().codecs },
@@ -75,6 +76,7 @@ module.exports = {
   DEFAULT_MAX_BW: 0,
   SHARED_POOL_WORKERS,
   DEDICATED_MEDIA_TYPE_WORKERS,
+  WORKER_PRIORITIES,
   WORKER_SETTINGS,
   WORKER_EXPORT_RESOURCE_USAGE,
   ROUTER_SETTINGS,

lib/mcs-core/lib/adapters/mediasoup/utils.js

@@ -2,6 +2,7 @@ const { MEDIA_TYPE, MEDIA_PROFILE } = require('../../constants/constants');
 const { MS_KINDS } = require('./constants.js');
 const { extractCodecsListFromSDP } = require('./sdp-translator.js');
 const Logger = require('../../utils/logger');
+const { setProcessPriority } = require('../../../../common/utils.js');
 
 const getMappedTransportType = (mcsCoreType) => {
   switch (mcsCoreType) {
@@ -108,4 +109,5 @@ module.exports = {
   filterValidMediaTypes,
   mapConnectionTypeToKind,
   replaceRouterCodecsWithSdpCodecs,
+  setProcessPriority,
 }

lib/mcs-core/lib/adapters/mediasoup/workers.js

@@ -6,11 +6,12 @@ const C = require('../../constants/constants');
 const { handleError } = require('./errors.js');
 const Logger = require('../../utils/logger');
 const {
-  WORKER_SETTINGS, WORKER_EXPORT_RESOURCE_USAGE,
+  WORKER_SETTINGS, WORKER_EXPORT_RESOURCE_USAGE, WORKER_PRIORITIES,
 } = require('./configs.js');
 const {
   PrometheusAgent, MS_METRIC_NAMES, exportWorkerResourceUsageMetrics
 } = require('./prom-metrics.js');
+const { setProcessPriority } = require('./utils.js');
 
 const SHARED_POOL_ID = 'shared';
 
@@ -216,6 +217,10 @@ const createDedicatedMediaTypeWorkers = (
     for (let i = 0; i < numberOfWorkers; i++) {
       createWorker({ workerSettings, mediaType }).then(worker => {
         storeWorker(worker);
+
+        if (WORKER_PRIORITIES[mediaType] != null) {
+          setProcessPriority(worker.pid, WORKER_PRIORITIES[mediaType]);
+        }
       }).catch(error => {
         Logger.error(`mediasoup: worker creation failed - ${mediaType}`,
           { mediaType, errorMessage: error.message, errorCode: error.code });