Blocked in function cluster.AcquireSocket

[dackon]

When mongodb is offline, the client will be blocked in the function cluster.AcquireSocket. Can you add a timeout for this situation? For example, if the client cannot get a live socket in 5s, it will return an error. Thank you.

To reproduce the problem:

1. Compile the following program.
2. Run the program
3. Login to your DB server, and execute the following commands, please replace $CLIENT_IP with your IP:
   sudo iptables -I INPUT -p tcp --dport 27017 -s $CLIENT_IP -j REJECT --reject-with tcp-reset
4. Check the output of the program, there is no '-------------ERROR is blah blah---------------' or '-------------OK---------------' printed.
5. Don't forget to delete the iptables commands:
   sudo iptables -D INPUT 1

Codes:

package main

import (
	"log"
	"os"
	"time"

	"github.com/globalsign/mgo"
	"github.com/globalsign/mgo/bson"
)

type barDoc struct {
	bar string `bson:"bar"`
}

func main() {
	var logger = log.New(os.Stderr, "", log.LstdFlags)
	mgo.SetLogger(logger)
	mgo.SetDebug(true)

	url := "user:password@IP:27017/foodb"
	sess, err := mgo.Dial(url)
	if err != nil {
		panic(err)
	}

	for {
		var results []*barDoc

		s := sess.Copy()
		col := sess.DB("foodb").C("bars")
		iter := col.Find(bson.M{}).Iter()

		err = iter.All(&results)

		if err != nil {
			logger.Printf("-------------ERROR is %s---------------", err)
		} else {
			logger.Printf("-------------OK---------------")
		}

		iter.Close()
		s.Close()

		time.Sleep(time.Second)
	}
}

[domodwyer]

Hi @leopoldfreeman

I think this is probably related to #120 - there's a hotfix pending but it's a public holiday in England, so my colleagues probably won't see it until everyone is back.

I'll close this as I think it should be resolved pretty soon but if it's not, please do reply and I'll reopen.

Dom

[domodwyer]

Hi @leopoldfreeman

Try now, it should be better :)

Dom

[dackon]

Hi, @domodwyer

I pulled the codes and rebuild the codes, the problem still exists. I checked the hotfix, it's not the same problem.

[dackon]

My problem is: When mongodb is offline after the client established the connection to the DB, this line will block:

iter := col.Find(bson.M{}).Iter()

[domodwyer]

Hi @leopoldfreeman

When running your test case, after a while I get:

-------------ERROR is read tcp 127.0.0.1:49602->127.0.0.1:27017: i/o timeout---------------

Perhaps changing the socket timeout or sync timeout might help.

Dom

[dackon]

I checked it again. You're right. Thank you very much.

[domodwyer]

Cool, glad it's working for you!