fix remotecommand stream blocked forever problems.

[adamzhoul]

What type of PR is this?
/kind bug

What this PR does / why we need it:

function blocked forever while it should exit

    func (p *streamProtocolV4) stream(conn streamCreator) error {

the bug is:

1. p.copyStdout(&wg)   return, but still have a lot of packet in the connection.  
2. watchErrorStream blocked.   because the connection is blocked by the stdout packet. 
3. the goroutine blocked because of this. It should get the error msg and exit.

why copyStdout return, but still have a lot of packets unconsumed?
check the code:

func (p *streamProtocolV2) copyStdout(wg *sync.WaitGroup) {
 ...
    if _, err := io.Copy(p.Stdout, p.remoteStdout); err != nil {
        runtime.HandleError(err)
    }
 ...
}

Check the code above:
p.remoteStdout may have problems, so the function return.
But p.Stdout still have data

So, we need to discard output data, to close the connection. Because it's finished.

Which issue(s) this PR fixes:

Fixes # #96339

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

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[k8s-ci-robot]

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[k8s-ci-robot]

Hi @adamzhoul. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[adamzhoul]

/retest

[k8s-ci-robot]

@adamzhoul: Cannot trigger testing until a trusted user reviews the PR and leaves an /ok-to-test message.

In response to this:

/retest

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[fedebongio]

/assign @yliaog
/cc @caesarxuchao
/triage accepted

[yliaog]

/ok-to-test

[yliaog]

thanks for the pr. please add a test to verify the fix.

[adamzhoul]

/test pull-kubernetes-e2e-kind

[adamzhoul]

/retest

[adamzhoul]

/retest

[adamzhoul]

/retest

[adamzhoul]

/retest

[adamzhoul]

/retest

[adamzhoul]

/retest

[adamzhoul]

hi @yliaog a test is added. please take some time to review.

by the way, the "pull-kubernetes-e2e-gce-ubuntu-containerd" check is not successful.
don't know what it is doing, still Investigating...

do you have any thoughts? didn't see any pass recently( almost a day ) by the way.
https://prow.k8s.io/job-history/gs/kubernetes-jenkins/pr-logs/directory/pull-kubernetes-e2e-gce-ubuntu-containerd?buildId=

thanks

[yliaog]

looks pull-kubernetes-e2e-gce-ubuntu-containerd has successful runs lately

[yliaog]

thanks for the pr
/lgtm

[adamzhoul]

thanks for the review and suggestions. they are very helpful.

[adamzhoul]

/assign @caesarxuchao
please take some time to review. thanks.

[adamzhoul]

hi lavalamp.
do you have some time to have a look at this? thanks.

/assign @lavalamp

[lavalamp]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: adamzhoul, lavalamp

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[adamzhoul]

hi @yliaog sorry to trouble you.

I use git rebase to squash commits, which creates a new commit.

maybe I need a new /lgtm label, do you mind?
don't know if another /approve is needed after...

thanks

[yliaog]

/lgtm