I set quite a few server-side timeouts with setTimeout and setInterval for each connected user that can last for 10-30 seconds. If the Node.js instance restarts in the middle of one of these timeouts, they are obviously all cleared on restart, which can cause some issues for these users. How would I go about persisting these timeouts, or are there any modules that already help with this?

I set quite a few server-side timeouts with setTimeout and setInterval for each connected user that can last for 10-30 seconds. If the Node.js instance restarts in the middle of one of these timeouts, they are obviously all cleared on restart, which can cause some issues for these users. How would I go about persisting these timeouts, or are there any modules that already help with this?

• javascript
• node.js
• settimeout
• setinterval

• can't you use node cron for this? – albertjan Commented Jul 12, 2012 at 18:43
• 1 How so? These are not cron jobs I'm setting up, they are 10-30 second timeouts based on user interactions with the app. – James Simpson Commented Jul 12, 2012 at 18:53
• You could use beanstalkd for that. It can even persist. – Alfred Commented Nov 28, 2012 at 23:22
• @JamesSimpson Did you get anywhere with this? – scanales Commented Dec 12, 2012 at 23:11
• Yes, I ended up doing something similar to Loc Nguyen's suggestion (looks like I forgot to mark it as the answer). This solution has worked very well, and it has been in production since August without issue. – James Simpson Commented Dec 19, 2012 at 18:41

2 Answers 2

setTimeOut takes delay as parameter, so when setting timeout, capture currentServerTime + delay say serverTriggerTime and persist this in DB. Then, on restart of server, create the same timer using the serverTriggerTime. Then, delay = serverTriggerTime - currentServerTime, use this delay to set new timer.

When setting timer

const date = Date.now();
const serverTriggerTime = date + delay; // time in milliseconds

On server restart:

serverTriggerTime = // retrieve from DB.
newDelay = serverTriggerTime - Date.now();

Also, set new timer only if newDelay >= 0, meaning the trigger time has not reached and will happen after newDelay time.

I would store the start times and durations in Redis and restart inplete timers when your application reloads. Some Redis modules:

https://github./joyent/node/wiki/modules#wiki-db-nosql-redis