feat(xen-api): limit concurrent calls to 20

Fixes xoa-support#3767

Can be changed via `callConcurrency` option.

CHANGELOG.unreleased.md

@@ -16,6 +16,7 @@
 
 - [IPs] Handle space-delimited IP address format provided by outdated guest tools [5801](https://github.com/vatesfr/xen-orchestra/issues/5801) (PR [5805](https://github.com/vatesfr/xen-orchestra/pull/5805))
 - [API/pool.listPoolsMatchingCriteria] fix `unknown error from the peer` error (PR [5807](https://github.com/vatesfr/xen-orchestra/pull/5807))
+- [Backup] Limit number of connections to hosts, which should reduce the occurences of `ECONNRESET`
 
 ### Packages to release
 

packages/xen-api/package.json

@@ -38,6 +38,7 @@
     "jest-diff": "^26.4.2",
     "json-rpc-protocol": "^0.13.1",
     "kindof": "^2.0.0",
+    "limit-concurrency-decorator": "^0.5.0",
     "lodash": "^4.17.4",
     "make-error": "^1.3.0",
     "minimist": "^1.2.0",

packages/xen-api/src/index.js

@@ -7,6 +7,7 @@ import { Collection } from 'xo-collection'
 import { EventEmitter } from 'events'
 import { map, noop, omit } from 'lodash'
 import { cancelable, defer, fromCallback, fromEvents, ignoreErrors, pDelay, pRetry, pTimeout } from 'promise-toolbox'
+import { limitConcurrency } from 'limit-concurrency-decorator'
 
 import autoTransport from './transports/auto'
 import coalesceCalls from './_coalesceCalls'
@@ -88,6 +89,8 @@ export class Xapi extends EventEmitter {
     this._RecordsByType = { __proto__: null }
     this._reverseHostIpAddresses = opts.reverseHostIpAddresses ?? false
 
+    this._call = limitConcurrency(opts.callConcurrency ?? 20)(this._call)
+
     this._roCallRetryOptions = {
       delay: 1e3,
       tries: 10,