A race is possible in etcd's Lock()

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#177 1 comment 0 reactions 0 assignees View on GitHub

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
35/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Stale
Tech stack
go
Domain
distributed-systems

Research direction

Start in store/etcd/etcd.go at the Lock() Set call around line 499, then read Unlock() around line 591 and trace how l.last is updated across concurrent calls. Confirm the failing interleaving described in the issue; done means a successful lock is still released by Unlock() even when another goroutine's Set() fails.

Written by the indexing model from the issue text.

Description

Consider line 499:

l.last, err = l.client.Set(context.Background(), l.key, l.value, setOpts)

It is possible for Set() to succeed, and immediately the following call to Set() from a different goroutine to fail - modifying l.last to be nil. Which will then result in Unlock() not issuing a Delete call and so not unlocking.

Dominant language
Go
Stars
847
Forks
204
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