Analysis of information sources in references of the Wikipedia article "Global interpreter lock" in English language version.
The GIL is a lock that is used to protect all the critical sections in Python. Hence, even if you have multiple CPUs, only one thread may be doing "pythony" things at a time.
It is important to understand at the outset that HammerDB is written in TCL because of the unique threading capabilities that TCL brings.
IronPython has no GIL and multi-threaded code can use multi core processors.
