Selecting the debugger

The debugger desired can be selected by setting the environment variable PYDBG. The following are valid values:

• pydevd or pycharm will use pydevd locally (if running in debug mode) or remotely if not

• pydevd_remote or pycharm_remote will use pydevd remotely

• pydevd_local or pycharm_local will use pydevd locally, and warn if not running in debug mode

• winpdb will use winpdb

• pdb will use pdb (default)

An environment variable is used so that imports of the debugger libraries can be determined at import time.

Inserting a tracepoint

Call dbg.D() to insert a tracepoint in the code; the appropriate debugger should launch when that line of code is executed, ready to execute the following line.

A thread-safe version dbg.tsD()``is also supported. This is only different when using ``pdb; in that case multiple threads having tracepoints (for example, in a web server) can cause confusion as multiple debug sessions get attached to the same console. The tsD implementation uses a lock to only allow one debug session to use the console at once; other sessions are not allowed the lock until the debug interaction is finished (e.g. typing c for continue).

Parameters for debuggers

Some debuggers have parameters that can be set using environment variables, or at runtime.

pydevd implementation will use the value of the environment variables PYDEVD_HOST for hostname and PYDEVD_PORT for port when connecting remotely by default. These can also be adjusted on by setting dbg.pydevd_args.host and dbg.pydevd_args.port at runtime.