[qoute=Kelly]We try reasonably hard to prevent sims from switching between hosts. We 'lock' sims to a host during new version deploys and sims try to come up on the same host if they crash or are restarted. Sometimes they can't, usually because the host is down or because the sim is crashing a *lot* or because it has been down for an extended period of time.
If it does happen (a sim gets moved to a different host), then yes it requires a visitor to request the textures before they will get cached.[/qoute]
Is there a way to identify when a sim is recaching? Something specific that we can see from the client, to tell it apart from other types of problems (run away scripts, grey goo, client lag, etc?)
I've noticed some sims that seem to sometimes have 28 to 50ms of "image" frame time -- is this a sim re-caching?
I've also noticed sims, and been in them with others, where it "stutters" for 5 to 15 minutes, with with serious spikes in dropped packets -- but all the sim stats (TD, Frame Time, etc) claim the sim is doing just fine.
Both of these conditions have been observed by multiple parties at the same time in the same sim or across multiple adjacent sims.
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Recaching a server? |
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Static Sprocket
Registered User
Join date: 10 Feb 2006
Posts: 157
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06-14-2006 20:39
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Kelly Linden
Linden Developer
Join date: 29 Mar 2004
Posts: 896
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06-14-2006 22:15
Asset caching is not done by the simulator process, and it really shouldn't effect the performance of a sim. We use squid proxies as our caching mechanism.
Where it is important is if many sims, a significant portion of the grid, lose their caches at once it can cause a higher than usual load for the asset servers which would result in a system wide effect. The primary indicator that something like this is happening is high upload and download queues on many sims. This is something we track.  If there are high upload and download queues on only a few sims it is probably not this issue. "High" in this case is usually 1,000+, though more than a few hundred for an extended period of time could be an indication of another problem.It used to be that the entire grid would experience poor asset performance after any full downtime. This is because we used to not lock simulators to their hosts before these down times. This would cause a lot of reshuffling, which meant a lot of lost caches, which meant a very high load on the asset system. Durring these times Second Life would "generally" work - teleports and logins would be slow, textures and avatars and items rezed from inventory could take a long time to appear, or a very long time. Ok, it really, really sucked. Which is why we fixed it. _____________________
- Kelly Linden
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