vesoft-inc/nebula

Session expire on graphd will end up floating session being released

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#5,094 opened on Dec 22, 2022

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affects/nonehelp wantedlaterseverity/minortype/bug

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Description

This is an issue talked about in WeChat Group:Earth, synced msg was pasted in the end of the issue.

It seems in current idle-release session mechanism was monitored and triggered in each graphD, that is, when a session(session-id:foo) was floated from graphd0 to graphd1, and will be actively used in graphd1 and not caming back to graphd0, after idle session timer expires in graphd0, foo will be released from graphd0.

I am on GitHub mobile(don't have access to the code to verify this)due to Covid leave, so just quickly track the issue here.

Plz forgive my unchecking of the code before raising this.

cc @Aiee

ref:

Contributor guide

Research direction
Analyze the idle release timer logic in graphd nodes and how sessions are migrated. Identify the race condition where a session floated to another graphd is released prematurely by the original graphd due to local idle timer expiry.
Tech stack
None
Domain
backenddatabase
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
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Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Mostly clear
Prerequisites
C++Distributed systems
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30