A brief discussion on how to do scheduled tasks in Nodejs

This article will introduce to you how to implementNodescheduled tasks. I hope it will be helpful to everyone!

Currently we have encountered such a demand. Each user can customize scheduled push. The time configuration of the scheduled task is configured by the user himself and can be modified at any time, instead of the traditional The server sets the time to run the scheduled task. [Recommended study: "nodejs Tutorial"]

If the scheduled task cycle is known, then Linux Crontab scheduled tasks can be implemented. There are already relatively mature solutions in node. Below I will introduce the Node scheduled task solution that I have learned about myself.

Schduler scheduled tasks provided by the egg framework

egg is Alibaba’s Node enterprise-level application framework. It provides a set of mechanisms for developers to elegantly write scheduled tasks. , please refer to the official documentation for details:https://eggjs.org/zh-cn/basics/schedule.html. The specific usage will not be elaborated here, but its configuration usage will be briefly discussed.

1. Static scheduled tasks, that is, scheduled cycles, have hard-coded processing logic.

2. Dynamically configure scheduled tasks, which is relatively more flexible. Developers can control the scheduled task cycle through configuration files.

3. Manually trigger scheduled tasks through code. We can determine whether to trigger scheduled tasks based on some logic.

From the above three points, the scheduled tasks provided by egg cannot meet our needs for users to configure the timing period by themselves, so we can only seek other solutions. By querying the data, we found that the node-schedule library also provides Scheduled task function.

node-schedule

After browsing the documentation of node-schudulehttps://www.npmjs.com/package/node-scheduleAfter that, its usage is as follows:

const schedule = require('node-schedule'); const job = schedule.scheduleJob('42 * * * *', function(){ console.log('The answer to life, the universe, and everything!'); });

Yes, it supports custom timing cycles, which can meet our needs and can be our choice. Nice!

Continue to browse other developers’ Using the article, I found a node-schedule related problem record. In short, the timer was executed twice at the scheduled time. For specific problems, see the original text:https://cnodejs.org/topic/5b58414b8d66b90b2b7384a7. This is a low-probability problem. We have not verified it. Because of our needs, the timer is executed twice and has no impact on our results. Therefore, this is not an obstacle that prevents us from using it. Interested students can go Test for bugs.

Written at the end

Finally, here is a summary of our own project’s scheduled task solutions. Students who are not interested can skip it.

Our backend uses the egg framework, so our final solution is to add a node-schdule timer to the agent process. The user's timer will be executed in the agent process synchronously. Currently we The number of users is not large, so I only think of this solution for the time being. After the volume is increased in the future, the backend may be deployed in a distributed manner.

This will be a problem, and running a single process with a large volume will also be a problem, and egg itself does not recommend doing too many business-related things in the agent process. Another important thing is that the agent is an auxiliary process. Some public work is completed in the agent. If an uncaught error occurs, the agent will not exit and restart, so fault tolerance processing must be done and done well.

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