Workaround for keepAlive false

lib/Connection.js

@@ -26,10 +26,13 @@ class Connection {
       throw new ConfigurationError(`Invalid protocol: '${this.url.protocol}'`)
     }
 
+    // Probably there is a bug in Node Core
+    // see https://github.com/nodejs/node/issues/26357
+    const keepAliveFalse = opts.agent && opts.agent.keepAlive === false
     const agentOptions = Object.assign({}, {
       keepAlive: true,
       keepAliveMsecs: 1000,
-      maxSockets: 256,
+      maxSockets: keepAliveFalse ? Infinity : 256,
       maxFreeSockets: 256
     }, opts.agent)
     this._agent = this.url.protocol === 'http:'