ID | IEP-83 |
Author | Pavel Tupitsyn |
Sponsor | Pavel Tupitsyn |
Created |
|
Status | DRAFT |
TCP connections can enter half-open state: 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) 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.
TCP has a built-in keepalive mechanism, but it has some disadvantages:
Because of that, some protocols implement keepalive logic on a higher level (SMB, TLS). More details: https://blog.stephencleary.com/2009/05/detection-of-half-open-dropped.html
Add OP_HEARTBEAT to the protocol with an empty payload. Clients can send heartbeats at a configurable interval and receive responses to ensure that the connection is active.
New ProtocolBitmaskFeature will be added to maintain protocol compatibility.
// Links to discussions on the devlist, if applicable.