A potential goleak in cluster.go

[xuxiaofan1203]

Description

Hello, I found in the function clusterLeave()

moby/libnetwork/networkdb/cluster.go

Line 222 in ceefb7d

func (nDB *NetworkDB) clusterLeave() error {

func (nDB *NetworkDB) clusterLeave() error {
	mlist := nDB.memberlist


	if err := nDB.sendNodeEvent(NodeEventTypeLeave); err != nil {
		log.G(context.TODO()).Errorf("failed to send node leave: %v", err)
	}


	if err := mlist.Leave(time.Second); err != nil {
		return err
	}


	// cancel the context
	nDB.cancelCtx()


	for _, t := range nDB.tickers {
		t.Stop()
	}


	return mlist.Shutdown()
}

If the mlist.Leave() return err, the nDB.cancelCtx() below will not get executed.

moby/libnetwork/networkdb/cluster.go

Lines 229 to 234 in ceefb7d

	if err := mlist.Leave(time.Second); err != nil {
	return err
	}
	// cancel the context
	nDB.cancelCtx()

And it will lead the <-nDB.ctx.Done in triggerFunc() blocked persistently, so the goroutine leak.

moby/libnetwork/networkdb/cluster.go

Line 176 in ceefb7d

go nDB.triggerFunc(trigger.interval, t.C, trigger.fn)

blocking position:

moby/libnetwork/networkdb/cluster.go

Lines 251 to 258 in ceefb7d

	for {
	select {
	case <-C:
	f()
	case <-nDB.ctx.Done():
	return
	}
	}

Reproduce

I reproduce the bug by goleak.
Firstly, I modified the judge condition from err != nil to err == nil. Because I don't know how to let err != nil, the change only to make the return err can be executed easier. I'm not sure whether the change can lead other influences.
Normally:

	if err := mlist.Leave(time.Second); err != nil {
		return err
	}

After modified:

	if err := mlist.Leave(time.Second); err == nil {
		return err
	}

Then I used goleak to test in these test function related the funciton.

moby/libnetwork/networkdb/networkdb_test.go

Line 180 in ceefb7d

func TestNetworkDBSimple(t *testing.T) {

Like this:

The result shows that there is a bug at the <-nDB.ctx.Done

Expected behavior

No response

docker version

latest

docker info

latest

Additional Info

In short, I think the bug is caused by return but have not called the cancelFunc. I have tried to describe it in detail.

[thaJeztah]

cc @akerouanton @corhere