JoSk
"JoSk" is a Node.js task manager package with a similar API to native setTimeout
and setInterval
methods, synced between all running instances via MongoDB.
This package supports clusters, multi-server, and multi-threaded Node.js instances, even when running on physically different machines and datacenters. This package goal is to ensure that the only single execution of each task (job, cron) occurs across a multi-server (multi-thread, multi-instance) setup.
JoSk package made for a server-only environment.
ToC:
Main features:
- 👨🔬 ~95% tests coverage;
- 📦 Zero dependencies, written from scratch for top performance;
- 🏢 Synchronize single task across multiple servers;
- 🔏 Collection locking to avoid simultaneous task executions across complex infrastructure;
- 💪 Bulletproof design, built-in retries, and "zombie" task recovery 🧟🔫.
Prerequisites
mongod@>=4.0.0
— (MongoDB Server) Due to the difference in driver's API we recommend to use mongod@4.*
or mongod@5.*
, for older setups use josk@=1.1.0
node@>=8.9.0
— For older setups use josk@=1.1.0
Install:
# for node@>=8.9.0 and mongod@>=4.0.0 (MongoDB server)
npm install josk --save
# for node@<8.9.0 and mongod@<4.0.0 (MongoDB server)
npm install josk@=1.1.0 --save
const JoSk = require('josk');
import JoSk from 'josk';
Install Meteor:
meteor add ostrio:cron-jobs
import JoSk from 'meteor/ostrio:cron-jobs';
Known Meteor Issues:
Error: Can't wait without a fiber
Can be easily solved via "bounding to Fiber":
const bound = Meteor.bindEnvironment((callback) => {
callback();
});
const db = Collection.rawDatabase();
const job = new JoSk({db: db});
const task = (ready) => {
bound(() => {
ready();
});
};
job.setInterval(task, 60 * 60 * 1000, 'task');
Notes:
- This package is perfect when you have multiple servers for load-balancing, durability, an array of micro-services or any other solution with multiple running copies of code when you need to run repeating tasks, and you need to run it only once per app, not per server;
- Limitation — task must be run not often than once per two seconds (from 2 to ∞ seconds). Example tasks: Email, SMS queue, Long-polling requests, Periodical application logic operations or Periodical data fetch and etc;
- Accuracy — Delay of each task depends on MongoDB and "de-synchronization delay". Trusted time-range of execution period is
task_delay ± (256 + MongoDB_Connection_And_Request_Delay)
. That means this package won't fit when you need to run a task with very certain delays. For other cases, if ±256 ms
delays are acceptable - this package is the great solution; - Use
opts.minRevolvingDelay
and opts.maxRevolvingDelay
to set the range for random delays between executions. Revolving range acts as a safety control to make sure different servers not picking the same task at the same time. Default values (128
and 768
) are the best for 3-server setup (the most common topology). Tune these options to match needs of your project. Higher opts.minRevolvingDelay
will reduce load on MongoDB; - To avoid "DB locks" — it's recommended to use separate DB from "main" application DB (same MongoDB server can have multiple DBs).
- This package implements "Collection Locking" via special collection ending with
.lock
prefix; - In total this package will add two new MongoDB collections per each
new JoSk({ prefix })
to a database it's connected.
API:
new JoSk({opts})
:
opts.db
{Object} - [Required] Connection to MongoDB, like returned as argument from MongoClient.connect()
opts.prefix
{String} - [Optional] use to create multiple named instancesopts.autoClear
{Boolean} - [Optional] Remove (Clear) obsolete tasks (any tasks which are not found in the instance memory (runtime), but exists in the database). Obsolete tasks may appear in cases when it wasn't cleared from the database on process shutdown, and/or was removed/renamed in the app. Obsolete tasks may appear if multiple app instances running different codebase within the same database, and the task may not exist on one of the instances. Default: false
opts.resetOnInit
{Boolean} - [Optional] make sure all old tasks is completed before setting a new one. Useful when you run a single instance of an app, or multiple app instances on one machine, in case machine was reloaded during running task and task is unfinishedopts.zombieTime
{Number} - [Optional] time in milliseconds, after this time - task will be interpreted as "zombie". This parameter allows to rescue task from "zombie mode" in case when: ready()
wasn't called, exception during runtime was thrown, or caused by bad logic. While resetOnInit
option helps to make sure tasks are done
on startup, zombieTime
option helps to solve same issue, but during runtime. Default value is 900000
(15 minutes). It's not recommended to set this value to less than a minute (60000ms)opts.minRevolvingDelay
{Number} - [Optional] Minimum revolving delay — the minimum delay between tasks executions in milliseconds. Default: 128
opts.maxRevolvingDelay
{Number} - [Optional] Maximum revolving delay — the maximum delay between tasks executions in milliseconds. Default: 768
opts.onError
{Function} - [Optional] Informational hook, called instead of throwing exceptions. Default: false
. Called with two arguments:
title
{String}details
{Object}details.description
{String}details.error
{Mix}details.uid
{String} - Internal uid
, suitable for .clearInterval()
and .clearTimeout()
opts.onExecuted
{Function} - [Optional] Informational hook, called when task is finished. Default: false
. Called with two arguments:
uid
{String} - uid
passed into .setImmediate()
, .setTimeout()
, or setInterval()
methodsdetails
{Object}details.uid
{String} - Internal uid
, suitable for .clearInterval()
and .clearTimeout()
details.date
{Date} - Execution timestamp as JS {Date}details.delay
{Number} - Execution delay
(e.g. interval
for .setInterval()
)details.timestamp
{Number} - Execution timestamp as unix {Number}
Initialization:
const options = {
writeConcern: {
j: true,
w: 'majority',
wtimeout: 30000
},
readConcern: {
level: 'linearizable'
},
readPreference: 'primary',
connectWithNoPrimary: false
};
MongoClient.connect('url', options, (error, client) => {
const db = client.db('dbName');
const job = new JoSk({db: db});
});
Initialization in Meteor:
import { MongoInternals } from 'meteor/mongo';
const db = MongoInternals.defaultRemoteCollectionDriver().mongo.db;
const job = new JoSk({db: db});
Note: This library relies on job ID, so you can not pass same job (with the same ID). Always use different uid
, even for the same task:
const task = function (ready) {
ready();
};
job.setInterval(task, 60 * 60 * 1000, 'task-1000');
job.setInterval(task, 60 * 60 * 2000, 'task-2000');
Passing arguments (not really fancy solution, sorry):
const job = new JoSk({db: db});
const myVar = { key: 'value' };
let myLet = 'Some top level or env.variable (can be changed during runtime)';
const task = function (arg1, arg2, ready) {
ready();
};
const taskA = function (ready) {
task(myVar, myLet, ready);
};
const taskB = function (ready) {
task({ otherKey: 'Another Value' }, 'Some other arguments', ready);
};
job.setInterval(taskA, 60 * 60 * 1000, 'taskA');
job.setInterval(taskB, 60 * 60 * 1000, 'taskB');
Note: To clean up old tasks via MongoDB use next query pattern:
db.getCollection('__JobTasks__').remove({});
db.getCollection('__JobTasks__PrefixHere').remove({});
setInterval(func, delay, uid)
func
{Function} - Function to call on scheduledelay
{Number} - Delay for first run and interval between further executions in millisecondsuid
{String} - Unique app-wide task id
Set task into interval execution loop. ready()
is passed as the first argument into task function.
In this example, next task will not be scheduled until the current is ready:
const syncTask = function (ready) {
ready();
};
const asyncTask = function (ready) {
asyncCall(function () {
ready();
});
};
job.setInterval(syncTask, 60 * 60 * 1000, 'syncTask');
job.setInterval(asyncTask, 60 * 60 * 1000, 'asyncTask');
In this example, next task will not wait for the current task to finish:
const syncTask = function (ready) {
ready();
};
const asyncTask = function (ready) {
ready();
asyncCall(function () {
});
};
job.setInterval(syncTask, 60 * 60 * 1000, 'syncTask');
job.setInterval(asyncTask, 60 * 60 * 1000, 'asyncTask');
In this example, we're assuming to have long running task, executed in a loop without delay, but after full execution:
const longRunningAsyncTask = function (ready) {
asyncCall((error, result) => {
if (error) {
ready();
} else {
anotherCall(result.data, ['param'], (error, response) => {
waitForSomethingElse(response, () => {
ready();
});
});
}
});
};
job.setInterval(longRunningAsyncTask, 0, 'longRunningAsyncTask');
setTimeout(func, delay, uid)
func
{Function} - Function to call on scheduledelay
{Number} - Delay in millisecondsuid
{String} - Unique app-wide task id
Set task into timeout execution. setTimeout
is useful for cluster - when you need to make sure task was executed only once. ready()
is passed as the first argument into task function.
const syncTask = function (ready) {
ready();
};
const asyncTask = function (ready) {
asyncCall(function () {
ready();
});
};
job.setTimeout(syncTask, 60 * 60 * 1000, 'syncTask');
job.setTimeout(asyncTask, 60 * 60 * 1000, 'asyncTask');
setImmediate(func, uid)
func
{Function} - Function to executeuid
{String} - Unique app-wide task id
Immediate execute the function, and only once. setImmediate
is useful for cluster - when you need to execute function immediately and only once across all servers. ready()
is passed as the first argument into the task function.
const syncTask = function (ready) {
ready();
};
const asyncTask = function (ready) {
asyncCall(function () {
ready();
});
};
job.setImmediate(syncTask, 'syncTask');
job.setImmediate(asyncTask, 'asyncTask');
clearInterval(timer)
Cancel (abort) current interval timer. Must be called in a separate event loop from setInterval
.
const timer = job.setInterval(func, 34789, 'unique-taskid');
job.clearInterval(timer);
clearTimeout(timer)
Cancel (abort) current timeout timer. Should be called in a separate event loop from setTimeout
.
const timer = job.setTimeout(func, 34789, 'unique-taskid');
job.clearTimeout(timer);
destroy()
Destroy JoSk instance. This method shouldn't be called in normal circumstances. Stop internal interval timer. After JoSk is destroyed — calling public methods would end up logged to std
or if onError
hook was passed to JoSk it would receive an error. Only permitted methods are clearTimeout
and clearInterval
.
const job = new JoSk({db: db});
const cleanUpBeforeTermination = function () {
job.destroy();
process.exit(1);
};
process.stdin.resume();
process.on('uncaughtException', cleanUpBeforeTermination);
process.on('exit', cleanUpBeforeTermination);
process.on('SIGHUP', cleanUpBeforeTermination);
Running Tests
- Clone this package
- In Terminal (Console) go to directory where package is cloned
- Then run:
# Before run tests make sure NODE_ENV === development
# Install NPM dependencies
npm install --save-dev
# Before run tests you need to have running MongoDB
MONGO_URL="mongodb://127.0.0.1:27017/npm-josk-test-001" npm test
# Be patient, tests are taking around 2 mins
Running Tests in Meteor environment
# Default
meteor test-packages ./ --driver-package=meteortesting:mocha
# With custom port
meteor test-packages ./ --driver-package=meteortesting:mocha --port 8888
# With local MongoDB and custom port
MONGO_URL="mongodb://127.0.0.1:27017/meteor-josk-test-001" meteor test-packages ./ --driver-package=meteortesting:mocha --port 8888
# Be patient, tests are taking around 2 mins
Why JoSk?
JoSk
is Job-Task - Is randomly generated name by "uniq" project
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