4 ms·

While I truly appreciate the effort... what the hell exactly goes into the Chromium's PDB file that it barely fits on a DVD-ROM? I am willing to bet that the ex

While I truly appreciate the effort... what the hell exactly goes into the Chromium's PDB file that it barely fits on a DVD-ROM? I am willing to bet that the executable and the source code combined together would take less space, so what is even in there?

planede 4y ago
If I had to guess, symbols for a lot of template instantiations.
kevingadd 4y ago
Web browsers contain a staggering amount of code, often linked into one huge binary so that LTCG can happen. They are basically an OS kernel+drivers+user space bundled into one.
the_mitsuhiko 4y ago
It's not just Chrome. We (Sentry) handle a lot of native crashes and the amount of really large debug symbols went up in recent years. C++ template instantiations are a huge reason for it.
- glandium 4y ago
  Rust generics are good at it too.
  - the_mitsuhiko 4y ago
    Absolutely and in some ways even worse. However Rust is in comparison with C and C++ a rather small player on our platform.
nwallin 4y ago
> what the hell exactly goes into the Chromium's PDB file that it barely fits on a DVD-ROM? Debug symbols in general tend to be very big. You need to be able to map each instruction in the binary to a line of code. You can expect a compiler to break each line of code into several instructions, and you can also expect that the instructions are out of order and interleaved with neighboring lines of code. So each instruction will need its own unique entry. > I am willing to bet that the executable and the source code combined together would take less space, ~ $ ll -h /var/cache/distfiles/chromium-110.0.5481.177.tar.xz -rw-rw-r-- 1 portage portage 1.6G Feb 22 11:02 /var/cache/distfiles/chromium-110.0.5481.177.tar.xz ~ $ tar -xaf /var/cache/distfiles/chromium-110.0.5481.177.tar.xz ~ $ du -sh chromium-110.0.5481.177/ 13G chromium-110.0.5481.177/
- Joker_vD 4y ago
  Excuse me? On Windows, "C:\Program Files (x86)\Google\Chrome" takes 603 MiB only — and it contains a 295 MiB file called "chrome.7z" inside an "Installer" subdirectory. What does Linux distribution contains that takes the rest of the space?
  - nwallin 4y ago
    That's not the Linux distribution, it's the source code. Straight from Google. https://commondatastorage.googleapis.com/chromium-browser-official/chromium-110.0.5481.177.tar.xz https://commondatastorage.googleapis.com/chromium-browser-of... The compiled binary is much smaller: ~ $ du -h /usr/lib64/chromium-browser 16K /usr/lib64/chromium-browser/MEIPreload 360K /usr/lib64/chromium-browser/locales 383M /usr/lib64/chromium-browser
    - Joker_vD 4y ago
      Huh, so the size comparison actually goes "compiled binary" < "debug symbols" < "source code", interesting to know, thanks.
      - ddulaney 4y ago
        Debug symbols are often larger than the original source code though. The main culprit is C++ template expansions, which can get crazy long.
- LanternLight83 4y ago
  Love the use of distfiles for an in the spot demonstration, makes me miss Gentoo. I suppose functional package-manager users have similar files in their stores. Thanks for sharing.
helloooooooo 4y ago
Because chromee is a) a project with a lot of code b) a lot of the code is templates and c) chrome provides full debug symbols which includes all symbol names, type information and source code line numbers.
- brucedawson 4y ago
  And local variables, including tracking where they are stored at various points in a function
xxpor 4y ago
I don't know literally a single thing about the PDB format, but assuming it at least somewhat similar to DWARF, it's REALLY easy to get an explosion of symbols in there, especially if you're looking at individual object files. A clean checkout of chromium is 5 GB (excluding the .git folder) by itself, the symbols will of course be larger.
Analemma_ 4y ago
C++ templates can result in huge symbol names, especially if you're using them for complex metaprogramming, which I assume Chrome is (especially for stuff like the JavaScript engine). But as another commenter alluded to, constexpr might help with this a little - if people choose to use it.

planede 4y ago

If I had to guess, symbols for a lot of template instantiations.

kevingadd 4y ago

Web browsers contain a staggering amount of code, often linked into one huge binary so that LTCG can happen. They are basically an OS kernel+drivers+user space bundled into one.

the_mitsuhiko 4y ago

It's not just Chrome. We (Sentry) handle a lot of native crashes and the amount of really large debug symbols went up in recent years. C++ template instantiations are a huge reason for it.

glandium 4y ago
Rust generics are good at it too.
- the_mitsuhiko 4y ago
  Absolutely and in some ways even worse. However Rust is in comparison with C and C++ a rather small player on our platform.

nwallin 4y ago

> what the hell exactly goes into the Chromium's PDB file that it barely fits on a DVD-ROM? Debug symbols in general tend to be very big. You need to be able to map each instruction in the binary to a line of code. You can expect a compiler to break each line of code into several instructions, and you can also expect that the instructions are out of order and interleaved with neighboring lines of code. So each instruction will need its own unique entry. > I am willing to bet that the executable and the source code combined together would take less space, ~ $ ll -h /var/cache/distfiles/chromium-110.0.5481.177.tar.xz -rw-rw-r-- 1 portage portage 1.6G Feb 22 11:02 /var/cache/distfiles/chromium-110.0.5481.177.tar.xz ~ $ tar -xaf /var/cache/distfiles/chromium-110.0.5481.177.tar.xz ~ $ du -sh chromium-110.0.5481.177/ 13G chromium-110.0.5481.177/

Joker_vD 4y ago
Excuse me? On Windows, "C:\Program Files (x86)\Google\Chrome" takes 603 MiB only — and it contains a 295 MiB file called "chrome.7z" inside an "Installer" subdirectory. What does Linux distribution contains that takes the rest of the space?
- nwallin 4y ago
  That's not the Linux distribution, it's the source code. Straight from Google. https://commondatastorage.googleapis.com/chromium-browser-official/chromium-110.0.5481.177.tar.xz https://commondatastorage.googleapis.com/chromium-browser-of... The compiled binary is much smaller: ~ $ du -h /usr/lib64/chromium-browser 16K /usr/lib64/chromium-browser/MEIPreload 360K /usr/lib64/chromium-browser/locales 383M /usr/lib64/chromium-browser
  - Joker_vD 4y ago
    Huh, so the size comparison actually goes "compiled binary" < "debug symbols" < "source code", interesting to know, thanks.
    - ddulaney 4y ago
      Debug symbols are often larger than the original source code though. The main culprit is C++ template expansions, which can get crazy long.
LanternLight83 4y ago
Love the use of distfiles for an in the spot demonstration, makes me miss Gentoo. I suppose functional package-manager users have similar files in their stores. Thanks for sharing.

helloooooooo 4y ago

Because chromee is a) a project with a lot of code b) a lot of the code is templates and c) chrome provides full debug symbols which includes all symbol names, type information and source code line numbers.

brucedawson 4y ago
And local variables, including tracking where they are stored at various points in a function

xxpor 4y ago

I don't know literally a single thing about the PDB format, but assuming it at least somewhat similar to DWARF, it's REALLY easy to get an explosion of symbols in there, especially if you're looking at individual object files. A clean checkout of chromium is 5 GB (excluding the .git folder) by itself, the symbols will of course be larger.

Analemma_ 4y ago

C++ templates can result in huge symbol names, especially if you're using them for complex metaprogramming, which I assume Chrome is (especially for stuff like the JavaScript engine). But as another commenter alluded to, constexpr might help with this a little - if people choose to use it.