PyDev 7.2.0 released

PyDev 7.2.0 is now available for download.

This version brings some improvements to the debugger and a fix for when PyDev could not properly find pipenv which could impact some users.

See: http://pydev.org for more details.

PyDev 7.0 (mypy, black, pipenv, faster debugger)

PyDev 7.0 (actually, PyDev 7.0.3 after some critical bugfixes on 7.0.0) is now available.

Some of the improvements available in this version include:

Mypy may be used as an additional backend for code analysis (see the preferences in the Preferences > PyDev > Editor > Code Analysis > Mypy). It is is similar to the PyLint integration, and will run Mypy whenever a file is saved in the editor.

Black can be used as the code-formatting engine (so, it's now possible to choose between the PyDev formatter, autopep8 or Black).

pipenv may be used for managing virtual environments (so, when creating a new project, clicking to configure an interpreter not listed will present an option to create a new interpreter with pipenv).

Improvements managing interpreters: it's now possible to manage interpreters directly from the editor (so, for instance, doing ctrl+2 pip install django will use pip to install django in the interpreter related to the opened editor -- and it's possible to change pip for conda or pipenv too).

Debugger improvements

The debugger is much faster for Python 3.6 onwards (when cython compiled extensions are available).

The performance improvement on the debugger is due to the using the frame eval mode for breakpoints again.

To give some history, that mode was previously disabled on pydevd because it had some issues which made function calls much slower (even though line stepping was zero overhead), but in the end, that overhead could make the performance worse than just using the plain tracing mode. Also, it had a big memory leak and in the cases where the tracing mode had to be reenabled both modes would be active at the same time and performance would suffer quite a bit.

-- all of those should be fixed and it should now perform better or at least on par with the tracing mode with cython in all scenarios... if you like numbers, see: https://github.com/fabioz/PyDev.Debugger/blob/master/tests_python/performance_check.py#L193 for some benchmarks.

p.s.: the improvements in the Debugger were sponsored by Microsoft, as the PyDev Debugger is used as the core of ptvsd, the Python debugger package used by Python in Visual Studio and the Python Extension for Visual Studio Code.

 

PyDev 6.5.0 (#region code folding)

PyDev 6.5.0 is now available for download.

There are some nice features and fixes available in this release:

• #region / #endregion comments can now be used by the code-folding engine.

• An action to easily switch the default interpreter is now available (default binding: Ctrl+Shift+Alt+I -- note that it must be executed with an opened editor).

• It's possible to create local imports from global imports (use Ctrl+1 on the name of a given global import and select "Move import to local scope(s)" -- although note that the global import needs to be manually deleted later on).

• The interactive interpreter now has scroll-lock.

• The debugger is much more responsive!

See: http://www.pydev.org for more details.

Profiling pytest startup

I'm a fan of pytest (http://www.pytest.org), yet, it seems that the startup time for running tests locally in the app I'm working on is slowly ramping up, so, I decided to do a profile to see if there was anything I could do to improve that.

The first thing I did was creating a simple test and launching it from the PyDev (http://www.pydev.org/) profile view -- it enables any launch done in PyDev to show its performance profile on PyVmMonitor (https://www.pyvmmonitor.com).

Note that this is an integration test that is starting up a big application, so, the total time just to startup all the fixtures which make the application live and shut down the fixtures is 15 seconds (quite a lot IMHO).

The first thing I noticed looking the profile is that 14% of that time seems to be creating a session temp dir:

After investigating a bit more it seems that there is a problem in the way the fixture used make_numbered_dir (it was passing a unicode when it should be a str on Python 2) and make_numbered_dir had an issue where big paths were not removed.

So, pytest always visited my old files every time I launched any test and that accounted for 1-2 seconds (I reported this particular error in: https://github.com/pytest-dev/pytest/issues/3810).

Ok, down from 15 to 13 seconds after manually removing old files with big paths and using the proper API with str on Py2.

Now, doing a new profile with that change has shown another pytest-related slowdown doing rewrites of test cases. 

This is because of a feature of pytest where it'll rewrite test files to provide a prettier stack trace when there's some assertion failure.

So, I passed --assert=plain to pytest and got 3 more seconds (from 13 down to 10) -- it seems all imports are a bit faster with the import rewrite disabled, so, I got an overall improvement there, not only in that specific part of the code (probably not nice on CI where I want to have more info, but seems like a nice plus locally, where I run many tests manually as I think the saved time for those runs will definitely be worth it even with less info when some assertion fails).

Now, with that disabled the next culprit seems to be getting its plugins to load:

But alas, it uses setuptools and I know from previous experience that it's very hard to improve that (it is very greedy in the way it handles loading metadata, so, stay away unless you're ok in wasting a lot of time on your imports) and the remainder of the time seems to be spread out importing many modules -- the app already tries to load things as lazy as possible... I think I'll be able to improve on that to delay some imports, but Python libraries are really hard to fix as everyone imports everything in the top of the module.

Well, I guess going from 15 s to 10 s with just a few changes is already an improvement in my case for an integrated tests which starts up the whole app (although it could certainly be better...) and I think I'll still be able to trim some of that time doing some more imports lazily -- although that's no longer really pytest-related, so, that's it for this post ;)

PyDev 6.4.3 (code formatter standalone, debugger improvements and f-strings handling)

The latest version of PyDev is now out...

Major changes in this release include:

1. Being able to use the PyDev code formatter as a standalone tool.

To use it it's possible to install it as pip install pydevf (the command line is provided as a python library which will call the actual formatter from PyDev -- see the README at https://github.com/fabioz/PyDev.Formatter for more details on how to use it).

The target of the PyDev formatter is trying to keep as close to the original structure of the code while fixing many common issues (so, it won't try to indent based on line width but will fix many common issues such as a space after a comma, space at start of comment, blank lines among methods and classes, etc).

2. Improvements to the debugger, such as:

• Thread creation is notified as threads are created instead of synchronized afterwards.
• Support for using frame evaluation disabled by default as it made the debugger much slower on some cases.
• Fixed case where breakpoint was missed if an exception was raised in a given line.
• Properly break on unhandled exceptions on threads.
• Add missing import which affected repl with IPython.
• Fix for case where breakpoints could be missed.

As a note, the debugger improvements have been sponsored by Microsoft, which is in the process of using the PyDev Debugger as the core of ptvsd, the Python debugger package used by Python in Visual Studio and the Python Extension for Visual Studio Code (note that it's still marked as experimental there as it's in the process of being integrated into ptvsd).

 It's really nice to see pydevd being used in more IDEs in the Python world! 😉

Besides those, there are some bugfixes in handling f-strings and sending the contents of the current line to the console (through F2).

Also, a new major version of LiClipse (5.0) is now also available (see: http://www.liclipse.com/download.html for how to get it). It includes the latest PyDev and a new major Eclipse release (4.8 - Photon).