Ulrich.Windl@rz.uni-regensburg.de wrote:
Full_Name: Ulrich Windl Version: 2.4.11 OS: Linux URL: ftp://ftp.openldap.org/incoming/ Submission from: (NULL) (132.199.156.178)
Looking for a threaded AVL tree implementation that is supposed to work, I found libraries/liblutil/tavl.c in openLDAP. I'm no expert on threaded AVL trees, but there's thing that worries me: tavl_delete uses two stacks (pptr, pdir) with a size of 8 elements on the routine' stack. While locating the element to delete, it pushes the parent node onto the stack.
You're misreading the code. The stack is 8*sizeof(void *) which means 32 elements deep on a 32 bit machine, and 64 deep on a 64 bit machine. There is no possibility of overflow now or for several years to come.
So from my knowledge this means that for a perfectly filled balanced tree, the stack will overflow when the tree consists of 2^8 (2^0 + 2^1 + 2^2 + ... + 2^7) or more nodes, and you are locating a leaf node. Maybe even with fewer nodes. As the algorithm also pushes an other element onto the stack, the problem could appear even before 128 nodes.