gh-101260: Return to a simpler output buffer for zlib, bz2 and lzma for better performance. #101279
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# Conflicts: # Modules/_bz2module.c
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See the accompanying issue for a detailed explanation. BlocksOutputBuffer was introduced in Python 3.10 and the benchmarks back then showed increased performance on larger output buffers. Smaller output buffers were not benchmarked however. In the accompanying issue I show why the previous buffer scheme works better for smaller output sizes. Since small data packets and streaming is more common than large in-memory compression it is beneficial to switch back to the 3.9 python style of arranging the buffers.
This also leads to a lot less code.
I changed one thing from the pthon 3.9 code: the lzma and bz2 buffer sizes do not follow a complex grow pattern but simply double the buffer (just like the zlib module). This only really hurts large in-memory compression but that is an anti-pattern anyway.