SL project news: week 2 (3): server, mesh and materials

Server Deployments – week 2

As noted in the update to part 2 of this week’s report, the planned deployment of two new releases to the RC channels didn’t go as anticipated. Originally, it had been intended that BlueSteel and LeTigre would received the new threaded region crossing code while Magnum would receive Andrew Linden’s interest list code improvements.

Interest List Deployment Cancellation

The interest list deployment was cancelled after the 11th hour discovery of some bugs with the code. Speaking at the Server Beta meeting on Thursday 10th January, Maestro Linden described the main issues as – ironically – being connected with region crossings, and with object updates.

In the first, anyone crossing between regions several times in a vehicle would experience all of their non-rigged attachments disappearing from their world view, with the viewer itself eventually physically detaching them. Not only did this cause confusion as to what was happening with attachments for those experiencing the issue, it also resulted in some avatars ending up naked following a relog.

Interest listcode: bugs led to deployment cancellation on Wednesday 9th January
Interest list code: bugs led to deployment cancellation on Wednesday 9th January

The second problem was slightly more complicated, if potentially more rare. In it, if User A had an object on the ground and User B looked at then turned their camera away such that the object was no longer on their screen, User A could then wear the object as an attachment and teleport away; however, when User B subsequently turned their camera back to where the object had been, they would still see it on the ground despite the fact it had been taken away. What happened if User A (now wearing the object) teleported back to User B wasn’t actually tested.

As a result of both of these issues and the cancellation of the interest list deployment, Magnum received the same region crossing package as intended for BlueSteel and LeTigre.

Region Crossing Code Issues

However, the bad news did not end there, as Maestro Linden explained, “After a few hours, we saw that the [region/sim] crash rate was way too high.” As a result, the threaded region crossing code was disabled via a configuration change to the servers without the need to rollback the release. Once this had happened, region crash rates returned to “normal” levels. In all the new region crossing code was active for around five hours before being disabled once more.

Analysis of the crash rate revealed it to be linked to avatars crossing to / from heavily scripted regions. While the new code was extensively tested on Aditi, the regions there were not excessively loaded with scripts during testing, and so the problem did not manifest. However, subsequent testing with the test regions running heavy script loads did result in them also crashing, confirming the problem.

At the time of writing, Kelly Linden believes he has a fix for the issue; if so, it should hopefully find its way to the RC channels in week 3, commencing Monday 14th January.

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