thread ctx, bdb search stack (ITS#2404)

[hyc@OpenLDAP.org]

Full_Name: Howard Chu
Version: 2.1.16, HEAD
OS: Linux
URL: 
Submission from: (NULL) (67.115.65.234)
Submitted by: hyc


Argh... The BDB search stack management assumes there is a 1-1 correspondence
between threads and thread contexts. This unfortunately isn't the case, the
thread pool creates a new context whenever a job is submitted to it and the pool
is backlogged. These contexts are on a queue and handed off to the next
available thread. In cases where more requests are queued than there are
threads, we wind up malloc'ing more search stacks than intended. Major pain...