"use of closed network connection" when running package tests

[ThreeFx]

When running the package tests using go test -v ./... the following errors occur, seemingly at random:

imap/client: 2020/06/29 01:35:27 error reading response: read tcp 127.0.0.1:37868->127.0.0.1:41003: use of closed network connection
...
imap/server: 2020/06/29 01:35:27 cannot read command: read tcp 127.0.0.1:34511->127.0.0.1:52710: use of closed network connection

The tests do not fail. I have no idea why these errors are produced.

[haytranngoc]

@ThreeFx You had fixed yet. Can you show me an example code?

[emersion]

Closing because this is an issue about go-imap v1. I'm now focusing on go-imap v2.

Please re-open if you can reproduce with go-imap v2.

[cui-dalihai]

we met the same error on go-imap v2.

import (
	"github.com/emersion/go-imap/v2"
	"github.com/emersion/go-imap/v2/imapclient"
)

type Watcher struct {
  cli          *imapclient.Client
}

func NewWatcher() (*Watcher, error) {
	cli, err := imapclient.DialTLS(c.Server, nil)
	if err != nil {
		return nil, err
	}
	err = cli.Login(c.Username, c.Password).Wait()
	if err != nil {
		return nil, err
	}
	_, err = cli.Select(c.BoxName, nil).Wait()
	if err != nil {
		return nil, err
	}
       go w.keepWatch()
       return &Watcher{
                cli: cli
       }
}

func (w *Watcher) keepWatch() {
	tk := time.NewTicker(10 * time.Second)
	for {
		select {
		case <-w.exit:
			return
		case <-tk.C:
		        res, err := w.cli.Search(cond, nil).Wait() // from since to now
	                if err != nil {
                               w.logger.Error("email search failed: ", err)
		               return
	                }
	               ids := res.AllNums()
                      // do some thing with email content
		}
	}
}

{"@timestamp":"2023-05-11T18:47:11.180+08:00","caller":"email/email.go:352","content":"email search failed: use of closed network connection","level":"error"}

This code is an example show how I use，In general, I make client and store it in a long running watcher, and every 10s I polling email server to get new email.

This code can normally run 1-2 day, then this "use of closed network connection" will appear, and I have to restart my code which means construct a new watcher, which means a new client.

thx for help 🙇‍

[emersion]

This is unrelated and just means the TCP connection to your server broke, which is a normal thing to happen.

[cui-dalihai]

Yeah, I think so, I'm going to construct a new client before every new round of requests to email server.

thx