Bat: Slow to open a JSON file containing 100,000 '[' characters

[ogham]

I was doing some JSON-related work, using the examples at https://github.com/nst/JSONTestSuite. My code passes _most_ of the test cases, but one that it failed on was n_structure_100000_opening_arrays.json — a file containing nothing but one hundred thousand open brackets.

I tried opening the file in bat to see what it was, and it gets as far as printing out the "File:" header, but after that, just takes up 100% CPU doing syntax highlighting! Running with -l text displays the file instantly.

(I had similar troubles opening this file in my text editor, so don't feel bad. GitHub straight up refuses to render the file, too.)

[sharkdp]

Thank you very much for reporting this.

That is unfortunate :disappointed:

This seems to be an issue with syntect, the (awesome) library that does the syntax highlighting for bat. I have reported the issue upstream: https://github.com/trishume/syntect/issues/201

[sharkdp]

Also related: https://github.com/trishume/syntect/issues/202

[nloadholtes]

I just noticed something unusual relating to this. The -p flag slows bat down considerably.

If I do bat -p some-minified-file.js it is incredibly slow to show each screenful, as in it takes over 2 seconds to draw the first page on the screen. Each page displays slower than the one before it, on the 3rd page I counted to 14 before it stopped rendering.

But if I do bat some-minified-file.js it is much faster, especially as I view each page. There doesn't seem to be any slow down as I page through the file.

Background: The js file is 381975 bytes. I noticed this because I made an alias for more to be bat -p.

[sharkdp]

I just noticed something unusual relating to this. The -p flag slows bat down considerably.

@nloadholtes Thank you for reporting this! I don't think this is related to this ticket (but I can reproduce this). Could you please open a new one?

[sharkdp]

I'm going to close this for now because there is nothing we can do here, but I'll keep an eye on the upstream ticket.