On 07 October 2004 20:53, Robert wrote:
I've been playing around with the "Hashes, Part II" code from the shootout. I wanted to try to implement this test using Data.HashTable instead of Data.FiniteMap to see if that would buy us anything. In fact, the HashTable implementation is consistantly faster than FiniteMap, but not by a lot (thus making the transition to the IO monad not worthwhile IMO). The interesting thing, however, is that at a certain number of iterations (106 in my case), the Hashtable code segfaults. GDB shows that it is blowing the top off the program stack and dying when it tries to write to kernel space. (can't write to 0xbfffffff).
Thanks, that's a good bug to catch just before the 6.2.2 release. There is a performance bug in the 6.2.2 HashTable implementation which we already found, but I forgot to merge into the 6.2 branch. The performance bug caused the table to overflow, leading to the segfault (not checking for overflow is another bug). Upshot: this will be fixed in 6.2.2. Furthermore, performance will be better. Cheers, Simon