Victor Stinner blog 3

In September 2017, during the CPython sprint at Facebook, I proposed my idea to create A New C API for CPython. I'm still working on the Python C API at: pythoncapi.readthedocs.io.

My analysis is that the C API leaks too many implementation details which prevent to optimize Python …

I added a new sys.unraisablehook function to allow to set a custom hook to control how "unraisable exceptions" are handled. It is already testable in Python 3.8 beta1, released last week!

An "unraisable exception" is an error which happens when Python cannot report it to the caller. Examples …

I fixed multiple bugs in asyncio ProactorEventLoop previously. But test_asyncio still failed sometimes. I noticed a memory leak in test_asyncio which will haunt me for 1 year in 2018...

Yet another example of a test failure which looks harmless but hides a critical bug. The bug is that sending a …

In December 2017, Yury Selivanov pushed the long awaited start_tls() function.

A newly added test failed on Windows. Later, the test started to fail randomly on Linux as well. In fact, it was a well hidden race condition in the asynchronous handshake of SSLProtocol which will take 5 months of …

Between December 2014 and January 2015, once I succeeded to fix the root issue of the random asyncio crashes on Windows (Proactor Cancellation From Hell), I fixed more race conditions and bugs in ProactorEventLoop:

• ConnectPipe() Race Condition
• Race Condition in BaseSubprocessTransport._try_finish()
• Close the transport on failure: ResourceWarning
• Cleanup code …

Between 2014 and 2015, I was working on the new shiny asyncio module (module added to Python 3.4 released in March 2014). I helped to stabilize the Windows implementation because... well, nobody else was paying attention to it, and I was worried that test_asyncio randomly crashed on Windows.

One …

This article describes a few locales bugs that I fixed in Python 3 between 2012 (Python 3.3) and 2018 (Python 3.7):

• Support non-ASCII decimal point and thousands separator
• Crash with non-ASCII decimal point
• LC_NUMERIC encoding different than LC_CTYPE encoding
• LC_MONETARY encoding different than LC_CTYPE encoding
• Tests non-ASCII locales …

Recently, I worked on a change which looked simple: move the code to initialize the sys.stdout encoding before Py_Initialize(). While I was on it, I also decided to move the code which selects the Python "filesystem encoding". I didn't expect that I would spend 2 weeks on these issues …

Since Python 3.0 was released in 2008, each time an user reported an encoding issue, someone showed up and asked why Python does not "simply" always use UTF-8. Well, it's not that easy. UTF-8 is the best encoding in most cases, but it is still not the best encoding …

During the childhood of Python 3, encodings issues were common, even on well configured systems. Python used UTF-8 rather than the locale encoding, and so commonly produced mojibake. For these reasons, when users complained about the Python behaviour with the POSIX locale, bug reports were closed with a message like …