[jira] [Updated] (IGNITE-16462) .NET: Thin client: implement heartbeats to detect half-open connections

["Pavel Tupitsyn (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IGNITE-16462?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Pavel Tupitsyn updated IGNITE-16462:
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    Summary: .NET: Thin client: implement heartbeats to detect half-open connections  (was: .NET: Thin client: add keep-alive message to detect half-open connections)

> .NET: Thin client: implement heartbeats to detect half-open connections
> -----------------------------------------------------------------------
>
>                 Key: IGNITE-16462
>                 URL: https://issues.apache.org/jira/browse/IGNITE-16462
>             Project: Ignite
>          Issue Type: Improvement
>          Components: platforms, thin client
>            Reporter: Pavel Tupitsyn
>            Assignee: Pavel Tupitsyn
>            Priority: Major
>              Labels: iep-83
>             Fix For: 2.13
>
>
> *Why*
> TCP connections can enter [half-open state|https://en.wikipedia.org/wiki/TCP_half-open]: seems to be alive, but any attempt to send data will fail. Long-living and mostly idle connections are especially susceptible to this behavior.
> Retry mechanism ([IEP-82 Thin Client Retry Policy|https://cwiki.apache.org/confluence/display/IGNITE/IEP-82+Thin+Client+Retry+Policy]) in thin client implementations partially mitigates the issue. However, not all operations are safe to retry, and reconnect affects performance.
> To improve the connection stability and detect failures early we can add a keep-alive mechanism.
> *Why not TCP keepalive*
> TCP has a [built-in keepalive mechanism|https://en.wikipedia.org/wiki/Keepalive], but it has some disadvantages:
> * Optional (may be not present in some TCP stacks)
> * May be not handled well by some routers (RFC 1122, section 4.2.3.6)
> * Default timeout is too long (2 hours), and is problematic to adjust on SDK versions that are in use in Ignite (Java 8, .NET Standard 2.0), or hard to do right in some languages (Python, JS).
> Because of that, some protocols implement keepalive logic on a higher level (SMB, [TLS|https://datatracker.ietf.org/doc/html/rfc6520]). More details: https://blog.stephencleary.com/2009/05/detection-of-half-open-dropped.html
> *How*
> Add OP_HEARTBEAT to the protocol with an empty payload. Clients can send heartbeats at a configurable interval and receive responses to ensure that connection is active.



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