mudd at vex.net
Sun Mar 28 05:32:04 EST 2004
I've been looking at bsddb3 lately. I don't think it's quite magic, unfortunately. It does support concurrent updates but you can still run into deadlocks (multi-user interference). And when you do all but one of the competing processes/threads loose. And, I think, that's only if you have the bsddb3 deadlock deamon running in the background to act as a traffic cop. Without the deamon I guess the processes are frozen. Of course, with a deamon, it's no longer very lightweight. The same is true for a commercial product that I've used, C-Tree Plus by Faircom. One difference is that C-Tree doesn't require a deamon process to resolve conflicts. The remedy for processes that get bumped due to deadlock is to simply try the update again until it succeeds. I think the mod_python developers are aware of the (rare) potential for deadlock with anydbm. They use the apache global lock when manipulating the session dbm. John Ben ben at medianstrip.net wrote: > sleepycat / bsddb3 handles locking automatically. after setting > the environment, you can use it like a dictionary and it works > like magic.