Codex Alimentarius (Nov 09 2011)

Funny story. About 3 years ago I realized that the BOINC database has result ids stored a integers, which are 4 bytes long and signed by default. The sign takes up one bit, thus leaving 31 bits remaining for the value. That means the maximum value is 2^31 (2 to the power of 31, or 2147483648). I mentioned this at this time, noting we were well on our way towards this maximum value, and put it on the "things we'll need to fix eventually" list.

Nobody has been really watching this (I've been pretty much out for over two months until this week), and sure enough we hit that limit yesterday, and the whole BOINC backend pretty much barfed. We tried to implement a "quick fix" by changing the result id signed integer to an unsigned integer (both in mysql and the C code), thus giving us an extra bit for the value. Now that means the maximum value is 2^32 (2 to the power of 32, or 4294967296). That should have bought us a couple more years.

However, this quick fix didn't really work. There's all kinds of code in BOINC that needs to be changed to get unsigned integers to work. Dave made some of these changes and Jeff tested them this morning, but still to no avail. More necessary fixes were found. We seem to be once again creating and sending out work at the moment. However the hood is wide open on BOINC now, so we're watching things carefully over the next day or so.

We're certainly not done - there are tons of cosmetic fixes that need to be made (our logs are full of entries containing negative result ids). In the long term we'll have to do the same for workunit ids, and at that point we'll probably go ahead and make them long longs (which are always 8 bytes, as opposed to longs, which are 4 bytes on 32-bit systems and 8 bytes on 64-bit systems) in the C code and bigints in mysql. At that point our id space will max out at 2305843009213693952, which should probably be enough. That's a million results a day for 6.3 billion years. If we're still running SETI@home 6.3 billion years from now there's probably nobody out there. Agreed?

We've been bitten by this long ago in informix, and have since been storing larger numbers there as int8's (8 byte integers) or doubles.

Warning: since we didn't come across this problem in advance and solve is gracefully, there may be some ugliness in the form of blocked results in weird states - these will most likely time out on their own and get resent. Sorry if this causes any confusion in the coming weeks.

By the way, it should be mentioned there were some random download server issues over this past weekend. No big deal - usual stuff regarding linux kernel hangs. We kicked the servers on monday morning and they went back to work.

- Matt

____________
-- BOINC/SETI@home network/web/science/development person
-- "Any idiot can have a good idea. What is hard is to do it." - Jeanne-Claude

Thanks for the update Matt,

Claggy

Warning: since we didn't come across this problem in advance and solve is gracefully, there may be some ugliness in the form of blocked results in weird states - these will most likely time out on their own and get resent. Sorry if this causes any confusion in the coming weeks.

How soon before the scheduler comes back up? - I can't report with the scheduler down - I've got about 18 results waiting on the scheduler... (would'a been more, but I was way down on SETI WU's before this... (except on two computers [out of 4])
____________
.

Thanks for the update. Let us know when the hood goes back down and gets latched.

____________

Just remember when you sort out those negative numbers, two's complement.

____________

Sorry. I know this is not the correct place to put this comment, but after read the posts of DrFoo and VW Bobier I couldn't resist to comment that I have an old ATARI 800, big as a typewritter, and one ATARI Mega ST, both still working fine. With these machines and a cartidge of Atari Basic began my sohn his informatics carrier. Today he is Master programmer, CCNT, and several titles more I don't remember...
In fact today I still playing with my three 7 to 13 y.o. Grandchildrens those old games like Karateka, Barbarian Fighter, Xenon and others, hand to hand, one joystich each...
And, want you now? Despite his own Core 4 or I3 or I7 machines both 3 are glad to play those old games, also with his Oldfather!

...short of using a PCXT to crunch with, Yes I know what one of those is capable of, I've been around that long.

You should upgrade that slow Intel chip with a NEC V20!

Thanks for the update Matt.

If we're still running SETI@home 6.3 billion years from now there's probably nobody out there. Agreed?

Getting back to SETI technical matters, I'm having trouble requesting new tasks, both on production and Beta, getting: "11/16/2011 7:46:34 AM SETI@home Beta Test Scheduler request failed: Failure when receiving data from the peer" almost every time I try: occasionally a Beta request will get through...


____________
.

Getting back to SETI technical matters, I'm having trouble requesting new tasks, both on production and Beta, getting: "11/16/2011 7:46:34 AM SETI@home Beta Test Scheduler request failed: Failure when receiving data from the peer" almost every time I try: occasionally a Beta request will get through...

Yes, but I thought the staff should be made aware...
____________
.