@paybase/pool
v1.1.6
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a pooling mechanism built on top of csp
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@paybase/pool
A highly flexible process pooling library for Node.js. Built with @paybase/csp.
Installation
$ npm install --save @paybase/pool
or
$ yarn add @paybase/pool
API
This library exposes a single factory method for creating pools.
createPool({ poolSize = 5, createProcess, createAsyncProcess, handler })
-> Pool|Promise<Pool>
The pool factory takes an options object containing 3 of 4 properties:
poolSize
- defaults to 5, determines the size of the poolcreateProcess
- defines aprocess
factory function which can return anythingcreateAsyncProcess
- defines an asyncprocess
factory which can return anything, useful if your process requires time to become active.handler(process, input)
->Promise
- defines a function which handles a unit of work. The handler must return aPromise
and receives aprocess
(as defined by theprocess
factory) and theinput
from a call torun
on the pool
You must supply only one of createProcess
or createAsyncProcess
! If you supply createAsyncProcess
the return value of the createPool
factory will be a Promise<Pool>
.
A returned Pool
exposes 2 methods:
Pool.run(input)
->Promise
- The interface defined to run against the pool of processes, supplied input can be of any type as the handler supplied atpool
creation defines how the input interacts which the underlying processPool.close
->Promise
- A mechanism for destroying thepool
when it is no longer needed
Example Usage
Network I/O parallelisation
By defining our process as a plain Symbol
, or true
for that matter, we can limit request parallelisation to the size of the pool.
const assert = require('assert');
const fetch = require('node-fetch');
const createPool = require('@paybase/pool');
const { run, close } = createPool({
poolSize: 2,
createProcess: () => Symbol('process'),
handler: (_, query) => {
console.log(`🚀 running request with query: ${query}`);
return fetch(`https://postman-echo.com/get?q=${query}`)
.then(res => res.json())
.then(res => assert.equal(res.args.q, query));
.then(_ => console.log(`👌 request completed successfully`));
}
});
(async () => {
const queries = Array.from({ length: 20 }, (_, i) => run(`${++i}`));
await Promise.all(queries);
close();
})();
Child process pooling
For spawning multiple child processes and spreading work across processes in the pool.
const assert = require('assert');
const { spawn } = require('child_process');
const createPool = require('@paybase/pool');
const { run, close } = createPool({
poolSize: 10,
createProcess: () => {
const p = spawn('cat', [ '-' ]);
p.stdin.setEncoding('utf-8');
p.stdout.setEncoding('utf-8');
return p;
},
handler: (p, input) =>
new Promise(resolve => {
p.stdout.once('data', d => {
assert(d, input);
console.log(`👌 received data: ${d.trim()} from pid: ${p.pid}`);
resolve(d);
});
console.log(`🚀 sending data: ${input.trim()} to pid: ${p.pid}`);
p.stdin.write(input);
}),
});
(async () => {
const inputs = Array.from({ length: 100 }, (_, i) => run(`${++i}\n`));
await Promise.all(inputs);
close();
})();
Contributions
Contributions are welcomed and appreciated!
- Fork this repository.
- Make your changes, documenting your new code with comments.
- Submit a pull request with a sane commit message.
Feel free to get in touch if you have any questions.
License
Please see the LICENSE
file for more information.