Thread Basics

The possibilities for threads in Python are shown. An examples is used to demonstrate how the module threading works.

GIL

Python has a so called General Interpreter Lock (GIL) that prevents several threads to run in real parallel on multi-CPU hardware. The implications of the GIL on programming are covered.

Thread Synchronization

Synchronization of threads is a important part of thread programming. Random manipulations of data has to be avoided when two threads access the same data at the same time. To achieve this data need to be locked by one thread providing exclusive access for this period of time.

Examples are used to explain the principles of locking. Special focus is put on so called dead-lock situations where threads block each other from executing and bring the program to a halt.

Processes

Python provides several ways to launch and access external processes. These ways are introduced with examples.

Combination of Threads und Processes

The combination of threads and processes allows to run programs in parallel using the advantages of multi-processor machines possibily gaining speedups. An example is used to demonstrate the effect of such combinations.