overleaf/libraries/metrics/open_sockets.js
Jakob Ackermann 2d1c84ea2e [misc] fix collection of open sockets
```
> require('http').globalAgent.sockets
{ 'HOST:PORT:': [{ ... }, { ... }] }
```

- `new URL('http://HOST:PORT:')` throws
  -> test suite `open_sockets`
- gauges were not cleaned up after no agents were present for a given
   key. This lead to continuous emission of the previous connection
   count for a given hostname, following the completion of all requests.
  -> test suite `when all requests complete`
2020-11-06 15:16:14 +00:00

52 lines
1.8 KiB
JavaScript

/*
* decaffeinate suggestions:
* DS102: Remove unnecessary code created because of implicit returns
* DS205: Consider reworking code to avoid use of IIFEs
* DS207: Consider shorter variations of null checks
* Full docs: https://github.com/decaffeinate/decaffeinate/blob/master/docs/suggestions.md
*/
let OpenSocketsMonitor
const seconds = 1000
// In Node 0.10 the default is 5, which means only 5 open connections at one.
// Node 0.12 has a default of Infinity. Make sure we have no limit set,
// regardless of Node version.
require('http').globalAgent.maxSockets = Infinity
require('https').globalAgent.maxSockets = Infinity
const SOCKETS_HTTP = require('http').globalAgent.sockets
const SOCKETS_HTTPS = require('https').globalAgent.sockets
// keep track of set gauges and reset them in the next collection cycle
const SEEN_HOSTS_HTTP = new Set()
const SEEN_HOSTS_HTTPS = new Set()
function collectOpenConnections(sockets, seenHosts, prefix) {
const Metrics = require('./index')
Object.keys(sockets).forEach(host => seenHosts.add(host))
seenHosts.forEach(host => {
// host: 'HOST:PORT:'
const hostname = host.split(':')[0]
const openConnections = (sockets[host] || []).length
if (!openConnections) {
seenHosts.delete(host)
}
Metrics.gauge(`open_connections.${prefix}.${hostname}`, openConnections)
})
}
module.exports = OpenSocketsMonitor = {
monitor(logger) {
const interval = setInterval(
() => OpenSocketsMonitor.gaugeOpenSockets(),
5 * seconds
)
const Metrics = require('./index')
return Metrics.registerDestructor(() => clearInterval(interval))
},
gaugeOpenSockets() {
collectOpenConnections(SOCKETS_HTTP, SEEN_HOSTS_HTTP, 'http')
collectOpenConnections(SOCKETS_HTTPS, SEEN_HOSTS_HTTPS, 'https')
}
}