RFR: 8297030: Reduce Default Keep-Alive Timeout Value for httpclient

[Daniel Fuchs]

On Tue, 22 Nov 2022 11:10:14 GMT, Conor Cleary <ccleary at openjdk.org> wrote:

> Proposed changes to reduce the default Keep Alive Timeout value in `jdk/internal/net/http/HttpClientImpl.java` from 1200 seconds to 30 seconds. The current default value of 1200s is needlessly high and in remote connections that allow a client to suggest a value, this will mean that idle connections will wait very long before being dropped.
> 
> This value of 30 seconds was chosen by reviewing the current default values for Keep-Alive timeouts in common server implementations and choosing a value that would have the client's default value be lower whenever the value can be set.
> 
> Further discussion on this change can be seen the pull request [8288717: Add a means to close idle connections in HTTP/2 connection pool #10183](https://github.com/openjdk/jdk/pull/10183).

I agree that 30s seems a much better default value than 1200s. Would be good to get @Michael-Mc-Mahon opinion too. This change will have to be coordinated with https://git.openjdk.org/jdk/pull/11241: Depending on which PR gets integrated first, you may have to update module-info (or leave it to Michael)

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Marked as reviewed by dfuchs (Reviewer).

PR: https://git.openjdk.org/jdk/pull/11285