node-redis/examples/backpressure_drain.js

'use strict';

var redis = require('../index'),
    client = redis.createClient(null, null, {
        command_queue_high_water: 5,
        command_queue_low_water: 1
    }),
    remaining_ops = 100000, paused = false;

function op() {
    if (remaining_ops <= 0) {
        console.error('Finished.');
        process.exit(0);
    }

    remaining_ops--;
    if (client.hset('test hash', 'val ' + remaining_ops, remaining_ops) === false) {
        console.log('Pausing at ' + remaining_ops);
        paused = true;
    } else {
        process.nextTick(op);
    }
}

client.on('drain', function () {
    if (paused) {
        console.log('Resuming at ' + remaining_ops);
        paused = false;
        process.nextTick(op);
    } else {
        console.log('Got drain while not paused at ' + remaining_ops);
    }
});

op();