Red screen of death?

[ferzle]

My students are having serious problems with Alice occasionally. They will work on a world for a while and once in a while when they try to save it pops up a message window with something like "Fatal Error" and a bunch of other stuff which I can't recall offhand, and then the background of the Alice window turns red. At this point they are unable to save their world anywhere. So it appears after a few hours of work, all of their work is lost with no way to recover it. When they stop and start Alice and try to reload the world, it gives an error because it was not saved properly.

Needless to say, this is a serious bug. I have a student who has done the same assignment for me 3 times, and still can't finish it because it has crashed this way for her every time. Aside from saving every few minutes to DIFFERENT filenames, I can't think of a way to help this situation, and saving many copies will of course take a lot of space.

The bug submission system is down, so I can't submit it there. Of course, that is another bug we have--every time we get an error it pops up a dialog, and then another saying it can't report the bug.

Another error we commonly get is when trying to cut and paste code--sometimes it works and sometime it gives an error. It seems like it works for a while and then once it fails once, it won't work again unless we restart Alice. Has this been reported before?

On a final note, I really like Alice, and we want to continue to use it, but if it is going to be unsupported for the next year or so until Alice 3.0 comes out, I can foresee some major problems.

If it helps, we are running Alice on HP Compaq tc4200 tablet PCs running Windows XP Tablet PC edition 2005 SP 2. The error also occurs one of the student's laptops running Windows XP, and it may occur on others that I do not know about.

[ferzle]

It just happened again. The title of the window contained
"Save error-CRITICAL"
and the message said:

"An error has occurred while attempting to save your world. This is a critical situation that needs to be dealt with immediately..."

It goes on for a few paragraphs saying something about submitting a bug report (which I can't) and apologizing for lost work, etc.

[chuck]

I can't be sure exactly what's causing the problems your students are having, but I can share a few things I and my students have learned.

First, there is a "garbage collection" error in the underlying Java part of the code for Alice. This means that Alice worlds use more and more memory each time they are run. Large worlds will crash more frequently than smaller worlds. There is no cure for this, but there are several things that can recude the frequency of the problem:

1. Every 15 minutes, by default, Alice warns you to save your files. It is a good idea to do so.

2. In the same directory where you saved your world, Alice will create a folder with backup copies of the world. For example, the third time you save a world, the previous two copies will be in the backup folder, with time signatures as part of the file name. Again, this is the default setting for Alice.

3. Every once in a while, especially after running a very large world file a few times, it is a good idea to re-start the Alice software. This will clear the memory. Also, it is a good idea to re-start Alice whenever you have finished one world and wish to start another -- aagin to clear the memory.

4. Don't have other programs that use a lot of memory, such as video software, graphics-itensive games, or 3D Studio Max, running while Alice is runnning.

5. Sound files in Alice worlds can consume a great deal of memory. Worlds with sound tracks that crash, sometimes run well when the sound is removed.

6. Avoid using computers with small memory or with shared memory. Many computers with a shared RAM - video memory and a video card built into the mother board are notorious for memory problems with graphics intensive software. Unfortuantely, many well meaning schools have purchased such machines thinking they are getting the most for their money. We bought PCs with a 1GB shared memory and had problems with Ailce, Desktop publishing software, and many other graphics intensive programs.

I use a Dell Latitiude 810 laptop with 512 Mb of memory and a 64 Mb video card often for Alice worlds, and keeping the tips above in mind, rarely have a world crash.

The problem is a pain in the neck, but I've been told that it almost certainly won't be addressed further for Alice 2.0, since the development effort is focussing on 3.0.

Of course, the trouble could be caused by something internal to the program. That doesn't happen often, but it can occur. If you have a particular world that keeps crashing (and you can save it) and you'd like to send me the file, I'd be glad to take a look at it and see what I can find.

The particular Save error you metioned could be caused by any of several different things -- a full dirEctory or disk, a bad file name, trying to write to a directory in which you do not have write permission, a hardware error, etc. -- usually this error occurs when the operating system throws an interrupt to Alice telling it that it can't write the file. It could also be caused by a memory error.

[ferzle]

Thanks for the reply. We have been doing most of what you have suggested, but when I looked at some of my student's directories recently I noticed that there weren't any recent backups, and I am not sure why. I have found that saving multiple times does not save multiple backup copies. It is not clear to me when Alice makes a backup and when it doesn't, but in my experience, it is not every time you save.

The first time this problem occurred we were using a wireless connection to a mapped drive which has been flaky on and off so I thought that was the cause, but when I then tried to save elsewhere--the C drive, etc.--it still would not save the world. Now that I think of it, maybe the users don't have write permission on the C: drive except in a few locations. Maybe if I had tried the desktop it would have worked. I will try that next time.

The fact that the screen turns red makes me think that some serious error has occurred in Alice and that it may not be recoverable, but I could be wrong.

As far as memory goes, I am not sure if they have shared video memory or not, but it is certainly possible. I am pretty sure they have at least 1 GB, though. I know I also have issues using sound files with Alice. On some computers they work O.K., on others they don't work well at all.

I really hope Alice 3.0 is out soon, because Alice 2.0 has some serious limitations that makes it difficult to use. And I hope Alice 3.0 uses inheritance, since there are some very weird quirks and limitations with Alice 2.0--for instance the fact that some objects have heads, others have necks which have heads, others have torsos with heads, etc. And as seen in your textbook, there are times when you have to do goofy things to get Alice to to do what you want. I should read up on the plans for Alice 3.0, but I have yet to find the time.

I still haven't decided what to do about the student who has lost the same program 3 times...

[DrJim]

The sound file problem seems to be pretty common - I've seen at least half a dozen reports of similar things on the forum in the last few months. One issue is that the files provided with Alice are fairly high quality and some sound cards just won't reproduce them - in other cases it's been a problem with the sound card itself. You can search the forum and see the responses, but I can't say that I've seen any obvious common cause.

One good thing to do is to see if the sound file will play by itself on the computer in question. If it doesn't, reformatting it to a lower quality format (say 8 kbps mono) using Sound Recorder sometimes helps.

Jim

[ottosparks]

No One Can Tell When A Critical Error Will Come.. But Yes It Is Goot To Save After Every 15 Mins. And I Can't Load One Of My Worlds (CRITICAL SAVE ERROR!!)