718413 - prune tabs for inactive clients

Status: RESOLVED INVALID

(Cloud Services Graveyard :: Server: Sync, defect)

Description

[:Atoll]

Clients that haven't existed in months are still showing their last set of tabs in his Firefox client. Let's prune the stale tabs entries from memcache, since they're just cluttering up our capacity and their user experience.

This may *also* be considered a client bug ("client shouldn't display tab data older than X"), but that's orthogonal from whether or not we prune stale tab data.

I'm aware that technically memcache tabs data is "one record", which merely makes it slightly more difficult to prune, not impossible.

Comment 1

[Tracy Walker [:tracy]]

atoll,

What process is happening to have "non-existent" devices?  If the user correctly disconnected client from the account, other clients should no longer show that device.  If that is not happening, then there is definitely a client bug. Not sure what an existing client can do about other devices/profiles that are simply no longer used.

Comment 2

[:Atoll]

(In reply to Tracy Walker [:tracy] from comment #1)
> atoll,
> 
> What process is happening to have "non-existent" devices?

Drop a Fennec device in a sink and you have a "nonexistent" device, from the perspective of my bug report.

> If the user
> correctly disconnected client from the account, other clients should no
> longer show that device.  If that is not happening, then there is definitely
> a client bug.

Device no longer available/responsive/lost/dead and thus cannot be disconnected correctly.

I'm aware of the "change sync key" workaround and that is not a solution to this bug report.

> Not sure what an existing client can do about other
> devices/profiles that are simply no longer used.

We can prune stale tabs on the server side to improve the client experience until Services ships client management someday. Or we can decide to do nothing, which is the current way of things. Ops doesn't care, this is entirely up to Eng.

Comment 3

[Toby Elliott [:telliott]]

Wouldn't giving tabs a TTL solve this problem? If expired tabs were coming back as results, that would be a bug.

Comment 4

[:Atoll]

We'll need to prune tabs for dead clients even if we add TTL support to the client (which, supposedly, we already did last year). Otherwise they grow unchecked and will eventually consume all storage, albeit more slowly than usual.

Comment 5

[Toby Elliott [:telliott]]

If we use TTLs, we shouldn't need any external pruning, really. Can do it on tab requests.

Comment 6

[:Atoll]

(In reply to Toby Elliott [:telliott] from comment #5)
> If we use TTLs, we shouldn't need any external pruning, really. Can do it on tab requests.

Yes, one option is to do blocking pruning, with a scan of *all* tabs records for *any* tab request. This is slower and will eventually fail to scale, same as the DELETE problem today, which is why I'm inclined towards external pruning (rather than blocking server requests to do it).  Up to you, though, either is fine for now.

Comment 7

[:Atoll]

No longer valid, closing.