Debugging and Profiling

When all hell breaks loose or your application is underperforming, debugging and profiling is the answer.

Debugging

Debugging your application can be done in several ways. Using your IDE, pdb, pudb,... There are many options, but here pdb and pudb will be explained.

Pdb

Pdb, the python debugger, is a minimal debugger that comes straight out of the box in python. It runs in the terminal and has a minimal interface.

Start pdb

python -m pdb manage.py run

Debug with pdb

Add breakpoints like so:

from pdb import set_trace
set_trace()

More debug-options can be found in the documentation.

Pudb

Pudb is a more interactive debugger. It runs in the terminal and has a nice interface which displays the code, stack, variables,...

Install pudb

1. Download the tar.gz from PyPi
2. Run ./setup.py install

Start pudb

pudb manage.py run

Debug with pudb

from pudb import set_trace
set_trace()

More debug-options can be found in the documentation.

Profiling

Edmunds comes with profiling built in. You can activate it in your settings:

from edmunds.profiler.drivers.callgraph import CallGraph
from edmunds.profiler.drivers.stream import Stream
from edmunds.profiler.drivers.blackfireio import BlackfireIo
import sys

APP = {
    'debug': True,
    'profiler':
    {
        'enabled': True,
        'instances':
        [
            {
                'name': 'stream',
                'driver': Stream,
                # 'stream': sys.stdout,     # Optional, default: sys.stdout
                # 'sort_by': ('calls'),     # Optional, default: ('time', 'calls')
                # 'restrictions': (),       # Optional, default: ()
            },
            {
                'name': 'callgraph',
                'driver': CallGraph,
                # 'directory': 'profs',     # Optional, default: 'profs'
                # 'prefix': 'Myapp.',       # Optional, default: ''
            },
            {
                'name': 'blackfireio',
                'driver': BlackfireIo,
                # 'directory': 'profs',     # Optional, default: 'profs'
                # 'prefix': 'Myapp.',       # Optional, default: ''
            },
        ],
    },
}

The instances will all be used for profiling, so you can have multiple at once.

The available drivers are:

• Stream: Print output in the given stream.
• CallGraph: Outputs in CallGraph-format to open in a viewer.
• BlackfireIo: Output in BlackfireIo-format to upload to Blackfire.io.