let sendPings const redis = require('@overleaf/redis-wrapper') const rclient1 = redis.createClient({ cluster: [ { port: '7000', host: 'localhost', }, ], }) const rclient2 = redis.createClient({ cluster: [ { port: '7000', host: 'localhost', }, ], }) let counter = 0 const sendPing = function (cb) { if (cb == null) { cb = function () {} } return rclient1.publish('test-pubsub', counter, error => { if (error) { console.error('[SENDING ERROR]', error.message) } if (error == null) { counter += 1 } return cb() }) } let previous = null rclient2.subscribe('test-pubsub') rclient2.on('message', (channel, value) => { value = parseInt(value, 10) if (value % 10 === 0) { console.log('.') } if (previous != null && value !== previous + 1) { console.error( '[RECEIVING ERROR]', `Counter not in order. Got ${value}, expected ${previous + 1}` ) } return (previous = value) }) const PING_DELAY = 100 ;(sendPings = () => sendPing(() => setTimeout(sendPings, PING_DELAY)))()