RFR: 8310996: Add JFR event for connect operations [v5]

[Erik Gahlin]

On Mon, 25 Nov 2024 12:00:52 GMT, Alan Bateman <alanb at openjdk.org> wrote:

>>> If a connection cannot be established then it might be immediate, 10s of milliseconds, maybe 60+ seconds in some cases. A slow down or stall waiting for a connection to be established seems a useful event to have recorded.
>> 
>> If it's immediate, a potential Socket Connection Failure event could overflow the buffers and we can't have it with threshold = 0s. Otherwise, it might be interesting to have something like:
>> 
>> `$ jfr view socket-connection-failures recording.jfr`
>> 
>> to see a complete list of failures per host/port and then have:
>> 
>> `$ jfr view slow-socket-connections recording.jfr`
>> 
>> to find which ones are slow, i.e. more than 10-20 ms.
>
> Having a view for connect failures that doesn't require exceptions=all could be useful. Does this mean two events, one an instant event for the failures, the other a duration event for the connections that are slow to establish?

A connection failure introduces a latency in the application, so probably best to have such an event durational as well.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21528#discussion_r1856610190