Remove ujson dependency and use python's json module

[rumpelsepp]

The ujson dependency ships a C-extension via a wheel which could cause unnecessary problems due to different versions of glibc in different environments, especially on NixOS:

import ujson as json
ImportError: /nix/store/9v5d40jyvmwgnq1nj8f19ji2rcc5dksd-glibc-2.37-45/lib/libc.so.6: version `GLIBC_2.38' not found (required by /nix/store/myw67gkgayf3s2mniij7zwd79lxy8v0k-gcc-12.3.0-lib/lib/libstdc++.so.6)

I propose removing this dependency, since I claim that the performance gain it did more than four years ago (added in 1c0c540) is not that much relevant any more. Here is a benchmark of several json implementations: https://github.com/TkTech/json_benchmark. The builtin json module is even faster than ujson in 50% of their benchmarks.

I claim, replacing ujson with the standard json module does not make any difference in practice; but it avoids compatability issues.

[ccordoba12]

I'm sorry but I'm going to say no to this due to the following:

• We're not interested in supporting really old Linux distros, you are. So, you can patch our pyproject.toml to remove the ujson dependency and then this package will use simply json.
• Any gain in speed we can obtain from a more performant Json library is really important for us. According to the benchmarks you referenced, I think we could switch to orjson.

[rumpelsepp]

Thanks for your answer. For the sake of correctness:

We're not interested in supporting really old Linux distros, you are

This is wrong. I did not propose supporting really old Linux distros, but very recent ones by not relying on libstdc++. Anyway, switching to orjson should also fix those problems as it relies on Rust instead. From my experience this causes fewer compatability issues with libc than C++ dependencies.

[ccordoba12]

Ok, sorry for the misunderstanding. I didn't know ujson is based on C++, which is causing the problem you reported.

Could you help us then to switch to orjson instead? I'll be happy to merge that PR.