Fix race condition when updating lastSeriesID during loading chunk snapshot

[damnever]

No description provided.

[codesome]

Nice catch!

[codesome]

Can you please fix the DCO? Thanks!

[roidelapluie]

What is the impact of this pull request? Should it have a test?

[damnever]

@codesome DCO fixed

@roidelapluie lastSeriesID is used to generate a new id for new series, the problem is this race condition may cause lastSeriesID less than the maximum we know, thus multiple different series may get the same id.

[roidelapluie]

I think a test is relevant. I also wonder what are the chances that this creates an infinite loop in the wild.

[damnever]

Maybe we should do some checks at the runtime since this kind of issue is severe.

I also wonder what are the chances that this creates an infinite loop in the wild.

I don't think this is an issue since the operation is fast and the runtime shouldn't schedule it away if we are in the CAS loop.

[codesome]

This might be hard to reproduce in a test. And I don't think we need a test to verify infinite loop, it will be limited to the number of series. I will merge this for now so that we can get it in the next release, and in the meantime we can see if we can write a test for this.