[Pharo-dev] WorkingSession UUID looks "sketchy"

Sven Van Caekenberghe sven at stfx.eu
Mon Feb 6 08:35:37 EST 2017


> On 6 Feb 2017, at 14:17, Yuriy Tymchuk <yuriy.tymchuk at me.com> wrote:
> 
> Hi everyone,
> 
> I’m using the session id (Smalltalk session id) for my data recording, so I can distinguish if the recorded events came from the same session. The idea is that each time an image is started a new session is created and assigned a new UUID. Now when I started to look on the data I noticed that I have some cases where I have same session IDs with different session creation times (yes a new session is initialized with a current timestamp). The time difference for the sessions with the same UUID and a different timestamp is within 2 hours. Then another thing that I did is to group the data by the timestamp and there are no cases where I have a different ID for the same timestamp, which shows that the timestamp is a more reliable ID. Now I will deal with my data just fine, but maybe we need to look in the implementation why do we get sessions with the same IDs?
> 
> Cheers.
> Uko

I would be very surprised it would happen with NeoUUIDGenerator (NeoUUIDGenerator next). The idea was to replace UUIDGenerator and the VM plugin by it. That got stalled when there was unforeseen interaction with WorkingSession. I believe that should be solved by now.

Still, UUIDs are not 100% guaranteed to be unique, they are a (very good) best effort.

But I agree that if they repeat in such a short time frame, that should be considered a bug.

Sven







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