chat lines appear later and out of sync

sometimes (but quite often recently) it happens to me that some of the lines i type appear later, sometimes even a few minutes after.

this is extremely annoying because it leads to bad misunderstanding.

this does not occur regularly. within a session, for instance, i may have lines appearing in sync (they show as i type them) and some lines out of sync...

much of SL communication is based on chat. having that out of sync spoils it so bad i just keep relogging... not a good way to solve that either.

typing in IM seems not to suffer from this kind of issue.

and i can't blame my pc or my connection since they are both very good... and all other features of SL are working fine.

This is a long-standing issue with SL. I call it "chat lag". Chat lag often happens with other kinds of lag, but not always.

I suspect that one cause of chat-lag is inefficient scripts. If you're wearing a necklace with 100 prims all of which respond to "bling on/bling off" on chat, then chances are this will cause chat lag. (I haven't tested this yet, so don't take it as gospel!) Likewise, if you're in an area where there are lots of objects that listen for commands from anyone, that probably contributes to chat lag. And, if there are lots of scripts running, especially inefficient ones (even ones that don't listen) this *might* contribute to chat lag.

Furthermore, script lag gets exacerbated by other kinds of server-side lag, up to a point. You see, the server reserves a certain amount of time for scripts and uses the rest for "physics". However, if it can get all the physics done and keep the frame rate high enough, it will give more time to scripts.

Complicated? Yup. Seriously, all the stuff that works together to make SL happen is quite complicated and the results are impressive, despite the flaws.

The fact that the same lag happens less often in IMs corroborates my suspicion that it's often related to scripts, because IMs aren't scanned by scripts the way normal chat can be. However, I'm pretty sure I've seen similar problems with IMs too, and in that case it's due to different kinds of server overloads. It may be that this has only happened when sending IMs to people in other sims; I can't recall ever seeing it when IMing a person nearby.

Oh, something I should point out. Don't assume that others see chat lines in the same order that you do. Lines that are out-of-order for you may appear in-order for others, and vice versa.

These problems are caused by SL doing something relatively simple and relatively robust. It could be fixed, but the increase in complexity might cause problems that are worse than the disease. My guess is that eventually they'll solve these problems but currently there are much bigger fish to fry. [Technically speaking, SL chat uses an "unordered multicast service". Changing it to an "ordered multicast service" is nontrivial.]

thank you for your posts... things are much clearer to me now.

i'll check whether people i talk to read my lines in correct order... that would be quite a relief.

also will try to see if i have on me objects that listen to chat commands, maybe this can lead to some optimization... and, yes, some bad written scripts can be blamed then i guess.

unfortunately, not everyone around (including me) has the knowledge to get over this kind of trouble... and chat lag can be really disrupting.

any hint would be highly appreciated! like... how to find listening objects around and on myself.

cheers!

Do you have packet loss? A good rule of thumb is that if you have packet loss on a regular basis, you should *decrease* your bandwidth.

If bandwidth is too high for your computer/network/ISP then SL will over run you, and you will lose packets. If that packet contains somebodies chat, then it is lost until SL sends it again later.

Good point. Lee's talking about in the bandwidth setting in Preferences, Networking tab. This is you giving SL a clue how good your bandwidth is.

You can tell whether you're getting lots of packet loss by the little colored indicator in the upper right -- the one on the left is packet loss (and there's a hover-tip).