RFR: 8288717: Add a means to close idle connections in HTTP/2 connection pool

[Jaikiran Pai]

On Tue, 6 Sep 2022 13:56:15 GMT, Conor Cleary <ccleary at openjdk.org> wrote:

> **Issue**
> When using HTTP/2 with the HttpClient, it can often be necessary to close an idle Http2 Connection before a server sends a GOAWAY frame. For example, a server or cloud based tool could close a TCP connection silently when it is idle for too long resulting in ConnectionResetException being thrown by the HttpClient.
> 
> **Proposed Solution**
> A new system property, `jdk.httpclient.idleConnectionTimeout`, was added and is used to specify in Milliseconds how long an idle connection (idle connections are those which have no currently active streams) for the HttpClient before the connection is closed.

src/java.net.http/share/classes/jdk/internal/net/http/Http2Connection.java line 201:

> 199:             }
> 200:             HttpTimeoutException hte = new HttpTimeoutException("HTTP connection idle, no active streams. Shutting down.");
> 201:             shutdown(hte);

The implementation in `shutdown` has some code which logs errors/exception when `error` logging is enabled. Specifically:


if (Log.errors()) {
  if (!(t instanceof EOFException) || isActive()) {
      Log.logError(t);

The implementation of `Log.logError` logs the exception stacktrace as well as a message which says `ERROR:`. Should we add a specific check in the `shutdown` implementation to prevent logging exception stacktraces when a connection is being closed due to idle timeout and instead just log it as an informational message?

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PR: https://git.openjdk.org/jdk/pull/10183