new http.Agent() is created for each socket in collector exporter instead of using single agent for all requests

[blumamir]

What version of OpenTelemetry are you using?

v0.14.0

What version of Node are you using?

12

This code from collector exporter creates a new Agent for each HTTP export request via the collector exporter:

export function sendWithHttp<ExportItem, ServiceRequest>(...): void {

  ...

  const request = parsedUrl.protocol === 'http:' ? http.request : https.request;
  const Agent = parsedUrl.protocol === 'http:' ? http.Agent : https.Agent;
  if (collector.keepAlive) {
    options.agent = new Agent({
      ...collector.httpAgentOptions,
      keepAlive: true,
    });
  }

  const req = request(options, (res: http.IncomingMessage) => {

I might be missing something, but shouldn't all the HTTP requests reuse the same Agent, in order to benefit from its connection persistence and reuse?

[blumamir]

I checked how axios and aws-sdk are using the agent.
It looks like they accept the agent as config parameter, rather than newing it in the library. This enables the user to configure it freely, and to share the connection pool and limits between multiple HTTP clients or exporters.
On the other hand, the user needs to be active about setting the use of agent, and it doesn't happen automatically by default.

in axios, this can be set in request config:

  // `httpAgent` and `httpsAgent` define a custom agent to be used when performing http
  // and https requests, respectively, in node.js. This allows options to be added like
  // `keepAlive` that are not enabled by default.
  httpAgent: new http.Agent({ keepAlive: true }),
  httpsAgent: new https.Agent({ keepAlive: true }),

In aws-sdk:

const AWS = require('aws-sdk')
// http or https
const https = require('https');
const agent = new https.Agent({
  keepAlive: true
});

const dynamodb = new AWS.DynamoDB({
  httpOptions: {
    agent
  }
});