Improve streaming server with cluster (#1970)

.env.production.sample

@@ -81,3 +81,7 @@ SMTP_FROM_ADDRESS=notifications@example.com
 # Advanced settings
 # If you need to use pgBouncer, you need to disable prepared statements:
 # PREPARED_STATEMENTS=false
+
+# Cluster number setting for streaming API server.
+# If you comment out following line, cluster number will be `numOfCpuCores - 1`.
+STREAMING_CLUSTER_NUM=1

streaming/index.js

@@ -1,3 +1,5 @@
+import os from 'os';
+import cluster from 'cluster';
 import dotenv from 'dotenv'
 import express from 'express'
 import http from 'http'
@@ -14,7 +16,24 @@ dotenv.config({
   path: env === 'production' ? '.env.production' : '.env'
 })
 
-const pgConfigs = {
+if (cluster.isMaster) {
+  // cluster master
+
+  const core = +process.env.STREAMING_CLUSTER_NUM || (env === 'development' ? 1 : os.cpus().length - 1)
+  const fork = () => {
+    const worker = cluster.fork();
+    worker.on('exit', (code, signal) => {
+      log.error(`Worker died with exit code ${code}, signal ${signal} received.`);
+      setTimeout(() => fork(), 0);
+    });
+  };
+  for (let i = 0; i < core; i++) fork();
+  log.info(`Starting streaming API server master with ${core} workers`)
+
+} else {
+  // cluster worker
+
+  const pgConfigs = {
     development: {
       database: 'mastodon_development',
       host:     '/var/run/postgresql',
@@ -29,22 +48,22 @@ const pgConfigs = {
       port:     process.env.DB_PORT || 5432,
       max:      10
     }
-}
+  }
 
-const app    = express()
-const pgPool = new pg.Pool(pgConfigs[env])
-const server = http.createServer(app)
-const wss    = new WebSocket.Server({ server })
+  const app    = express()
+  const pgPool = new pg.Pool(pgConfigs[env])
+  const server = http.createServer(app)
+  const wss    = new WebSocket.Server({ server })
 
-const redisClient = redis.createClient({
+  const redisClient = redis.createClient({
     host:     process.env.REDIS_HOST     || '127.0.0.1',
     port:     process.env.REDIS_PORT     || 6379,
     password: process.env.REDIS_PASSWORD
-})
+  })
 
-const subs = {}
+  const subs = {}
 
-redisClient.on('pmessage', (_, channel, message) => {
+  redisClient.on('pmessage', (_, channel, message) => {
     const callbacks = subs[channel]
 
     log.silly(`New message on channel ${channel}`)
@@ -54,37 +73,37 @@ redisClient.on('pmessage', (_, channel, message) => {
     }
 
     callbacks.forEach(callback => callback(message))
-})
+  })
 
-redisClient.psubscribe('timeline:*')
+  redisClient.psubscribe('timeline:*')
 
-const subscribe = (channel, callback) => {
+  const subscribe = (channel, callback) => {
     log.silly(`Adding listener for ${channel}`)
     subs[channel] = subs[channel] || []
     subs[channel].push(callback)
-}
+  }
 
-const unsubscribe = (channel, callback) => {
+  const unsubscribe = (channel, callback) => {
     log.silly(`Removing listener for ${channel}`)
     subs[channel] = subs[channel].filter(item => item !== callback)
-}
+  }
 
-const allowCrossDomain = (req, res, next) => {
+  const allowCrossDomain = (req, res, next) => {
     res.header('Access-Control-Allow-Origin', '*')
     res.header('Access-Control-Allow-Headers', 'Authorization, Accept, Cache-Control')
     res.header('Access-Control-Allow-Methods', 'GET, OPTIONS')
 
     next()
-}
+  }
 
-const setRequestId = (req, res, next) => {
+  const setRequestId = (req, res, next) => {
     req.requestId = uuid.v4()
     res.header('X-Request-Id', req.requestId)
 
     next()
-}
+  }
 
-const accountFromToken = (token, req, next) => {
+  const accountFromToken = (token, req, next) => {
     pgPool.connect((err, client, done) => {
       if (err) {
         next(err)
@@ -112,9 +131,9 @@ const accountFromToken = (token, req, next) => {
         next()
       })
     })
-}
+  }
 
-const authenticationMiddleware = (req, res, next) => {
+  const authenticationMiddleware = (req, res, next) => {
     if (req.method === 'OPTIONS') {
       next()
       return
@@ -133,17 +152,17 @@ const authenticationMiddleware = (req, res, next) => {
     const token = authorization.replace(/^Bearer /, '')
 
     accountFromToken(token, req, next)
-}
+  }
 
-const errorMiddleware = (err, req, res, next) => {
+  const errorMiddleware = (err, req, res, next) => {
     log.error(req.requestId, err)
     res.writeHead(err.statusCode || 500, { 'Content-Type': 'application/json' })
     res.end(JSON.stringify({ error: err.statusCode ? `${err}` : 'An unexpected error occurred' }))
-}
+  }
 
-const placeholders = (arr, shift = 0) => arr.map((_, i) => `$${i + 1 + shift}`).join(', ');
+  const placeholders = (arr, shift = 0) => arr.map((_, i) => `$${i + 1 + shift}`).join(', ');
 
-const streamFrom = (id, req, output, attachCloseHandler, needsFiltering = false) => {
+  const streamFrom = (id, req, output, attachCloseHandler, needsFiltering = false) => {
     log.verbose(req.requestId, `Starting stream from ${id} for ${req.accountId}`)
 
     const listener = message => {
@@ -191,10 +210,10 @@ const streamFrom = (id, req, output, attachCloseHandler, needsFiltering = false)
 
     subscribe(id, listener)
     attachCloseHandler(id, listener)
-}
+  }
 
-// Setup stream output to HTTP
-const streamToHttp = (req, res) => {
+  // Setup stream output to HTTP
+  const streamToHttp = (req, res) => {
     res.setHeader('Content-Type', 'text/event-stream')
     res.setHeader('Transfer-Encoding', 'chunked')
 
@@ -209,17 +228,17 @@ const streamToHttp = (req, res) => {
       res.write(`event: ${event}\n`)
       res.write(`data: ${payload}\n\n`)
     }
-}
+  }
 
-// Setup stream end for HTTP
-const streamHttpEnd = req => (id, listener) => {
+  // Setup stream end for HTTP
+  const streamHttpEnd = req => (id, listener) => {
     req.on('close', () => {
       unsubscribe(id, listener)
     })
-}
+  }
 
-// Setup stream output to WebSockets
-const streamToWs = (req, ws) => {
+  // Setup stream output to WebSockets
+  const streamToWs = (req, ws) => {
     const heartbeat = setInterval(() => ws.ping(), 15000)
 
     ws.on('close', () => {
@@ -235,10 +254,10 @@ const streamToWs = (req, ws) => {
 
       ws.send(JSON.stringify({ event, payload }))
     }
-}
+  }
 
-// Setup stream end for WebSockets
-const streamWsEnd = ws => (id, listener) => {
+  // Setup stream end for WebSockets
+  const streamWsEnd = ws => (id, listener) => {
     ws.on('close', () => {
       unsubscribe(id, listener)
     })
@@ -246,34 +265,34 @@ const streamWsEnd = ws => (id, listener) => {
     ws.on('error', e => {
       unsubscribe(id, listener)
     })
-}
+  }
 
-app.use(setRequestId)
-app.use(allowCrossDomain)
-app.use(authenticationMiddleware)
-app.use(errorMiddleware)
+  app.use(setRequestId)
+  app.use(allowCrossDomain)
+  app.use(authenticationMiddleware)
+  app.use(errorMiddleware)
 
-app.get('/api/v1/streaming/user', (req, res) => {
+  app.get('/api/v1/streaming/user', (req, res) => {
     streamFrom(`timeline:${req.accountId}`, req, streamToHttp(req, res), streamHttpEnd(req))
-})
+  })
 
-app.get('/api/v1/streaming/public', (req, res) => {
+  app.get('/api/v1/streaming/public', (req, res) => {
     streamFrom('timeline:public', req, streamToHttp(req, res), streamHttpEnd(req), true)
-})
+  })
 
-app.get('/api/v1/streaming/public/local', (req, res) => {
+  app.get('/api/v1/streaming/public/local', (req, res) => {
     streamFrom('timeline:public:local', req, streamToHttp(req, res), streamHttpEnd(req), true)
-})
+  })
 
-app.get('/api/v1/streaming/hashtag', (req, res) => {
+  app.get('/api/v1/streaming/hashtag', (req, res) => {
     streamFrom(`timeline:hashtag:${req.params.tag}`, req, streamToHttp(req, res), streamHttpEnd(req), true)
-})
+  })
 
-app.get('/api/v1/streaming/hashtag/local', (req, res) => {
+  app.get('/api/v1/streaming/hashtag/local', (req, res) => {
     streamFrom(`timeline:hashtag:${req.params.tag}:local`, req, streamToHttp(req, res), streamHttpEnd(req), true)
-})
+  })
 
-wss.on('connection', ws => {
+  wss.on('connection', ws => {
     const location = url.parse(ws.upgradeReq.url, true)
     const token    = location.query.access_token
     const req      = { requestId: uuid.v4() }
@@ -305,9 +324,10 @@ wss.on('connection', ws => {
         ws.close()
       }
     })
-})
+  })
 
-server.listen(process.env.PORT || 4000, () => {
+  server.listen(process.env.PORT || 4000, () => {
     log.level = process.env.LOG_LEVEL || 'verbose'
-  log.info(`Starting streaming API server on port ${server.address().port}`)
-})
+    log.info(`Starting streaming API server worker on port ${server.address().port}`)
+  })
+}