246 lines
7.9 KiB
Markdown
246 lines
7.9 KiB
Markdown
# agentkeepalive
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[![NPM version][npm-image]][npm-url]
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[![Known Vulnerabilities][snyk-image]][snyk-url]
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[](https://github.com/node-modules/agentkeepalive/actions/workflows/nodejs.yml)
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[![npm download][download-image]][download-url]
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[npm-image]: https://img.shields.io/npm/v/agentkeepalive.svg?style=flat
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[npm-url]: https://npmjs.org/package/agentkeepalive
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[snyk-image]: https://snyk.io/test/npm/agentkeepalive/badge.svg?style=flat-square
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[snyk-url]: https://snyk.io/test/npm/agentkeepalive
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[download-image]: https://img.shields.io/npm/dm/agentkeepalive.svg?style=flat-square
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[download-url]: https://npmjs.org/package/agentkeepalive
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The enhancement features `keep alive` `http.Agent`. Support `http` and `https`.
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## What's different from original `http.Agent`?
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- `keepAlive=true` by default
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- Disable Nagle's algorithm: `socket.setNoDelay(true)`
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- Add free socket timeout: avoid long time inactivity socket leak in the free-sockets queue.
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- Add active socket timeout: avoid long time inactivity socket leak in the active-sockets queue.
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- TTL for active socket.
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## Node.js version required
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Support Node.js >= `8.0.0`
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## Install
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```bash
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$ npm install agentkeepalive --save
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```
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## new Agent([options])
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* `options` {Object} Set of configurable options to set on the agent.
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Can have the following fields:
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* `keepAlive` {Boolean} Keep sockets around in a pool to be used by
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other requests in the future. Default = `true`.
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* `keepAliveMsecs` {Number} When using the keepAlive option, specifies the initial delay
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for TCP Keep-Alive packets. Ignored when the keepAlive option is false or undefined. Defaults to 1000.
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Default = `1000`. Only relevant if `keepAlive` is set to `true`.
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* `freeSocketTimeout`: {Number} Sets the free socket to timeout
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after `freeSocketTimeout` milliseconds of inactivity on the free socket.
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The default [server-side timeout](https://nodejs.org/api/http.html#serverkeepalivetimeout) is 5000 milliseconds, to [avoid ECONNRESET exceptions](https://medium.com/ssense-tech/reduce-networking-errors-in-nodejs-23b4eb9f2d83), we set the default value to `4000` milliseconds.
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Only relevant if `keepAlive` is set to `true`.
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* `timeout`: {Number} Sets the working socket to timeout
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after `timeout` milliseconds of inactivity on the working socket.
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Default is `freeSocketTimeout * 2` so long as that value is greater than or equal to 8 seconds, otherwise the default is 8 seconds.
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* `maxSockets` {Number} Maximum number of sockets to allow per
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host. Default = `Infinity`.
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* `maxFreeSockets` {Number} Maximum number of sockets (per host) to leave open
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in a free state. Only relevant if `keepAlive` is set to `true`.
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Default = `256`.
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* `socketActiveTTL` {Number} Sets the socket active time to live, even if it's in use.
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If not set, the behaviour keeps the same (the socket will be released only when free)
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Default = `null`.
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## Usage
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```js
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const http = require('http');
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const Agent = require('agentkeepalive');
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const keepaliveAgent = new Agent({
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maxSockets: 100,
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maxFreeSockets: 10,
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timeout: 60000, // active socket keepalive for 60 seconds
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freeSocketTimeout: 30000, // free socket keepalive for 30 seconds
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});
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const options = {
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host: 'cnodejs.org',
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port: 80,
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path: '/',
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method: 'GET',
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agent: keepaliveAgent,
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};
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const req = http.request(options, res => {
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console.log('STATUS: ' + res.statusCode);
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console.log('HEADERS: ' + JSON.stringify(res.headers));
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res.setEncoding('utf8');
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res.on('data', function (chunk) {
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console.log('BODY: ' + chunk);
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});
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});
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req.on('error', e => {
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console.log('problem with request: ' + e.message);
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});
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req.end();
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setTimeout(() => {
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if (keepaliveAgent.statusChanged) {
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console.log('[%s] agent status changed: %j', Date(), keepaliveAgent.getCurrentStatus());
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}
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}, 2000);
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```
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### `getter agent.statusChanged`
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counters have change or not after last checkpoint.
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### `agent.getCurrentStatus()`
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`agent.getCurrentStatus()` will return a object to show the status of this agent:
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```js
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{
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createSocketCount: 10,
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closeSocketCount: 5,
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timeoutSocketCount: 0,
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requestCount: 5,
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freeSockets: { 'localhost:57479:': 3 },
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sockets: { 'localhost:57479:': 5 },
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requests: {}
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}
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```
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### Support `https`
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```js
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const https = require('https');
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const HttpsAgent = require('agentkeepalive').HttpsAgent;
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const keepaliveAgent = new HttpsAgent();
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// https://www.google.com/search?q=nodejs&sugexp=chrome,mod=12&sourceid=chrome&ie=UTF-8
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const options = {
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host: 'www.google.com',
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port: 443,
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path: '/search?q=nodejs&sugexp=chrome,mod=12&sourceid=chrome&ie=UTF-8',
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method: 'GET',
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agent: keepaliveAgent,
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};
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const req = https.request(options, res => {
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console.log('STATUS: ' + res.statusCode);
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console.log('HEADERS: ' + JSON.stringify(res.headers));
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res.setEncoding('utf8');
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res.on('data', chunk => {
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console.log('BODY: ' + chunk);
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});
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});
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req.on('error', e => {
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console.log('problem with request: ' + e.message);
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});
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req.end();
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setTimeout(() => {
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console.log('agent status: %j', keepaliveAgent.getCurrentStatus());
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}, 2000);
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```
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### Support `req.reusedSocket`
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This agent implements the `req.reusedSocket` to determine whether a request is send through a reused socket.
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When server closes connection at unfortunate time ([keep-alive race](https://code-examples.net/en/q/28a8069)), the http client will throw a `ECONNRESET` error. Under this circumstance, `req.reusedSocket` is useful when we want to retry the request automatically.
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```js
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const http = require('http');
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const Agent = require('agentkeepalive');
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const agent = new Agent();
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const req = http
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.get('http://localhost:3000', { agent }, (res) => {
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// ...
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})
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.on('error', (err) => {
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if (req.reusedSocket && err.code === 'ECONNRESET') {
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// retry the request or anything else...
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}
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})
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```
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This behavior is consistent with Node.js core. But through `agentkeepalive`, you can use this feature in older Node.js version.
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## [Benchmark](https://github.com/node-modules/agentkeepalive/tree/master/benchmark)
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run the benchmark:
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```bash
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cd benchmark
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sh start.sh
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```
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Intel(R) Core(TM)2 Duo CPU P8600 @ 2.40GHz
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node@v0.8.9
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50 maxSockets, 60 concurrent, 1000 requests per concurrent, 5ms delay
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Keep alive agent (30 seconds):
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```js
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Transactions: 60000 hits
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Availability: 100.00 %
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Elapsed time: 29.70 secs
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Data transferred: 14.88 MB
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Response time: 0.03 secs
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Transaction rate: 2020.20 trans/sec
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Throughput: 0.50 MB/sec
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Concurrency: 59.84
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Successful transactions: 60000
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Failed transactions: 0
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Longest transaction: 0.15
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Shortest transaction: 0.01
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```
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Normal agent:
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```js
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Transactions: 60000 hits
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Availability: 100.00 %
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Elapsed time: 46.53 secs
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Data transferred: 14.88 MB
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Response time: 0.05 secs
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Transaction rate: 1289.49 trans/sec
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Throughput: 0.32 MB/sec
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Concurrency: 59.81
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Successful transactions: 60000
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Failed transactions: 0
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Longest transaction: 0.45
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Shortest transaction: 0.00
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```
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Socket created:
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```bash
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[proxy.js:120000] keepalive, 50 created, 60000 requestFinished, 1200 req/socket, 0 requests, 0 sockets, 0 unusedSockets, 50 timeout
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{" <10ms":662," <15ms":17825," <20ms":20552," <30ms":17646," <40ms":2315," <50ms":567," <100ms":377," <150ms":56," <200ms":0," >=200ms+":0}
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----------------------------------------------------------------
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[proxy.js:120000] normal , 53866 created, 84260 requestFinished, 1.56 req/socket, 0 requests, 0 sockets
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{" <10ms":75," <15ms":1112," <20ms":10947," <30ms":32130," <40ms":8228," <50ms":3002," <100ms":4274," <150ms":181," <200ms":18," >=200ms+":33}
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```
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## License
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[MIT](LICENSE)
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## Contributors
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[](https://github.com/node-modules/agentkeepalive/graphs/contributors)
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