Substantial Degradation in Performance (Roughly 58-fold) When Downloading and Storing Small Files in Parallel on Windows 11

[ilotoki0804]

Bug report

Bug description:

During the development of my personal project, I noticed that the Python 3.12 multithreading on Windows 11 consumes significantly more CPU resources and operates at a noticeably slower pace compared to 3.11.

To assess the speed, I conducted a benchmark. The results of the benchmark indicate the following:

• The multiprocessing.pool.ThreadPool is 1.76 times slower and consumes 33.09 times more CPU.
• The threading.Thread is 1.51 times slower and consumes 26.18 times more CPU.
• The multiprocessing.pool.ThreadPool on Windows Sandbox is 1.07 times slower and consumes 120.15 times more CPU in version 3.12 compared to version 3.11.4.

These characteristics were not observed during experimentation with WSL(Ubuntu). In fact, I was unable to obtain the final result due to the considerably slow operation of both Python 3.11 and 3.12.

I have compiled the results of the performance tests in a repository, which can be accessed via this link.

My system: Windows 11 Pro x64 23H2, AMD 5900HX

CPython versions tested on:

3.12

Operating systems tested on:

Windows

[neonene]

Could you check whether #95031 (or #109386) has your issue?

[ilotoki0804]

@neonene When I tested it on Python 3.11.6, which uses OpenSSL 3, the identical problem is occurred. I think it shows that I have the same issue with #95031.