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WSGI Middleware version of the CherryPy memory leak debugger

Project description


Dozer was originally a WSGI middleware version of Robert Brewer’s Dowser CherryPy tool that displays information as collected by the gc module to assist in tracking down memory leaks. It now also has middleware for profiling and for looking at logged messages.

Tracking down memory leaks


from dozer import Dozer

# my_wsgi_app is a WSGI application
wsgi_app = Dozer(my_wsgi_app)

Assuming you’re serving your application on the localhost at port 5000, you can then load up http://localhost:5000/_dozer/index to view the gc info.

Profiling requests


from dozer import Profiler

# my_wsgi_app is a WSGI application
wsgi_app = Profiler(my_wsgi_app)

Assuming you’re serving your application on the localhost at port 5000, you can then load up http://localhost:5000/_profiler to view the list of recorded request profiles.

Here’s a blog post by Marius Gedminas that contains a longer description of Dozer’s profiler.

Inspecting log messages


from dozer import Logview

# my_wsgi_app is a WSGI application
wsgi_app = Logview(my_wsgi_app)

Every text/html page served by your application will get some HTML and Javascript injected into the response body listing all logging messages produced by the thread that generated this response.

Here’s a blog post by Marius Gedminas that contains a longer description of Dozer’s logview.

Dozer Changelog

0.8 (November 13, 2020)

  • Add support for Python 3.8 and 3.9.

  • Drop support for Python 3.5.

  • Add UI input for existing “floor” query string parameter (

  • Add UI input to filter type charts by a regular expression

  • Add sorting option: monotonicity

  • Display traceback on 500 Internal Server Error

  • Dicts and sets with unsortable keys are no longer unrepresentable

  • Aggregate dynamically-created types with the same __name__ and __module__ (issue 9).

0.7 (April 23, 2019)

  • Add support for Python 3.7.

  • Drop support for Python 3.3 and 3.4.

  • Stop using cgi.escape on Python 3, which is especially important now that it’s been removed from Python 3.8.

0.6 (May 18, 2017)

  • Add support for Python 3.6.

  • Drop support for Python 2.6.

  • Fix rare TypeError when listing profiles, if two profiles happen to have the exact same timestamp (

0.5 (December 2, 2015)

  • Make /_dozer show the index page (instead of an internal server error).

  • Add support for Python 3.4 and 3.5.

  • Drop support for Python 2.5.

  • Move to GitHub.

0.4 (March 21, 2013)

  • 100% test coverage.

  • Add support for Python 3.2 or newer.

  • Drop dependency on Paste.

0.3.2 (February 10, 2013)

0.3.1 (February 6, 2013)

0.3 (December 13, 2012)

  • Emit the “PIL is not installed” only if the Dozer middleware is actually used.

  • Give a name to the Dozer memleak thread.

  • You can now supply a function directly to Logview(stack_formatter=fn)

  • New configuration option for Logview middleware: tb_formatter, similar to stack_formatter, but for exception tracebacks.

0.2 (December 5, 2012)

  • Adding logview that appends log events for the current request to the bottom of the html output for html requests.

  • Adding profiler for request profiling and call tree viewing.

  • Refactored Dozer into its own leak package.

  • New maintainer: Marius Gedminas.

0.1 (June 14, 2008)

  • Initial public release, port from Dowser, a CherryPy tool.

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