[JENKINS-46659] Avoid Jetty timeouts by sending pings

[jglick]

See JENKINS-46659.

Proposed changelog entries

• Avoid a possible server-side timeout on long-running CLI commands using plain HTTP mode by sending periodic pings from the client.

Desired reviewers

@reviewbybees

[ghost]

This pull request originates from a CloudBees employee. At CloudBees, we require that all pull requests be reviewed by other CloudBees employees before we seek to have the change accepted. If you want to learn more about our process please see this explanation.

[oleg-nenashev]

Any chance it collides with stdin.write(c);, e.g. during long send operations like file parameter upload?

[jglick]

@oleg-nenashev should be safe. The (non-delegating) send overloads are all synchronized.

[ghost]

This pull request originates from a CloudBees employee. At CloudBees, we require that all pull requests be reviewed by other CloudBees employees before we seek to have the change accepted. If you want to learn more about our process please see this explanation.

[oleg-nenashev]

🐝

[oleg-nenashev]

@reviewbybees done

[oleg-nenashev]

I am going to merge it to the next weekly if nobody votes against

[daniel-beck]

Per JENKINS-59267 the timeout seems to be 5 seconds in recent Jenkins/Winstone/Jetty, so the 10 second interval is too great.

How expensive is this? Would going with 3-4 seconds solve this without introducing a ton of load?

[jglick]

Sure, that would be fine I think.