Jython

Jython is a Java implementation of the language. It compiles the code into Java byte code, and allows the developers to seamlessly use Java classes within their Python modules. Jython allows people to use Python as the top-level scripting language on complex application systems, for example, J2EE. It also brings Java applications into the Python world. Making Apache Jackrabbit (which is a document repository API based on JCR; see http://jackrabbit.apache.org) available in a Python program is a good example of what Jython allows.

The main differences of Jython compared to the CPython implementation are as follows:

• True Java's garbage collection instead of reference counting
• Lack of global interpreter lock (GIL) allows better utilization of multiple cores in multi-threaded applications

The main weakness of this implementation of the language is the lack of support for C Python Extension APIs, so no Python extensions written in C will work with Jython.

The latest available version of Jython is Jython 2.7, and this corresponds to the 2.7 version of the language. It is advertised as implementing nearly all of the core Python standard library and using the same regression test suite. Unfortunately, Jython 3.x was never released, and the project can be now safely considered dead. However, Jython is still worth mentioning, even if it is not developed anymore, because it was very unique implementation at the time and had meaningful impact on other alternative Python implementations.

The official project page can be found at http://www.jython.org.