🤖 New build scheduled with the buildbot fleet by @gpshead for commit d200d19 🤖

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This is a draft because I'm seeing sporadic crashing behavior when I use a non-USE_ZLIB_CRC32 build that I need to understand first.

Other functions in binascii.c do not release GIL, I suggest not releasing GIL here as well.
Then no need for if (data->len > 1024*5) condition check.

Or discuss "the problem of GIL in binascii.c" in python-dev.

Other functions in binascii.c do not release GIL, I suggest not releasing GIL here as well. Then no need for if (data->len > 1024*5) condition check.

Or discuss "the problem of GIL in binascii.c" in python-dev.

crc32 is a hash function, hash functions are stand alone computational time sinks. zlib's crc32 does this as does everything in hashlib:

https://github.com/python/cpython/blob/main/Modules/zlibmodule.c#L1436
https://github.com/python/cpython/blob/main/Modules/_hashopenssl.c#L578

The ultimate end state for binascii and zlib crc32 is to be a single identical piece of code somewhere. This is another step in that direction as the code in the two is now identical.

@python/windows-team if you could confirm my PCbuild edit to add a preprocessor define. It appears to work on the CI windows builds and looks correct based on other things I see in the file.

Windows builds always require zlib from what I can tell, so having binascii.c always use zlib.h there for a 2-3x faster crc32 implementation makes sense.

Most POSIX systems have zlib so it happens by default thanks to configure on those platforms.

🤖 New build scheduled with the buildbot fleet by @gpshead for commit 65222b2 🤖

If you want to schedule another build, you need to add the ":hammer: test-with-buildbots" label again.

I confirm MSVC build's binascii.crc32() is faster.
Computing 5 GiB data, this commit speedups from 8.34 sec to 3.23 sec.

It would be nice if Linux/macOS builds could use it as well.
It's supposed, but don't know why it doesn't work. In configure file:

if test "x$have_zlib" = xyes; then :

  BINASCII_CFLAGS="-DUSE_ZLIB_CRC32 $ZLIB_CFLAGS"
  BINASCII_LIBS="$ZLIB_LIBS"

fi

https://github.com/python/cpython/blob/v3.11.0a6/configure

It does work on Linux and BSD if the zlib-devel or zlib1g-dev or whatever similar package is installed when you do your own builds. Note that Linux distro packagers may do things that alter how their configure and build works.

I'd prefer to move zlib to "required" status instead of optional. It'd simplify and shrink a pile of code... Testing to see if that is possible: https://bugs.python.org/issue47090

I'd prefer to move zlib to "required" status instead of optional.

Maybe some thin systems do not have zlib configured, such as some embedded systems.
Is it possible to find a fast crc32 implementation to replace the binascii.crc32() implementation?