9 ms·

Mold 2.0

430 points by fomine3 3y ago

AlbertoGP 3y ago
I had forgotten that it was a fast linker: > Mold 2.0.0 is a new major release of our high-speed linker. With this release, we've transitioned our license from AGPL to MIT, aiming to expand the user base of our linker. This was not an easy decision, as those who have been following our progress know that we've been attempting to monetize our product through an AGPL/commercial license dual-licensing scheme. Unfortunately, this approach didn't meet our expectations. The license change represents our acceptance of this reality. We don't want to persist with a strategy that didn't work well.
- latchkey 3y ago
  Anyone remember having to pay for cc on Solaris? [0] It was horrible and a terrible way to treat developers who are writing software for your OS! We have been conditioned for a very long time to not need to pay for low level developer tools and to pay for support instead. I'm surprised they even tried to license it like that. [0] https://unix.stackexchange.com/questions/12731/usr-ucb-cc-language-optional-software-package-not-installed https://unix.stackexchange.com/questions/12731/usr-ucb-cc-la...
  - tingletech 3y ago
    At work in the 90s I was allowed to buy a brand new sparc workstation with a shrinkwrap compiler (and shrinkwrap sybase). One of the first things I did was compile gcc so I could install the whole gnu world.
    - latchkey 3y ago
      Exactly! I begged someone random for a gcc tarball.
      - dmvdoug 3y ago
        Now I am imagining you panhandling on the sidewalk, stopping random strangers and shaking slightly: “hey man, can you spare a gcc tarball?”
    - jsrcout 3y ago
      They did the same at my first job out of college (Sun based company). It was my first introduction to free software. That was circa 1990... it's amazing that gcc is still going strong.
  - wrs 3y ago
    There’s a distinction between the maker of the OS/hardware and an independent vendor trying to monetize the tools. The OS/hardware maker’s primary interest is in selling more OS or hardware, so it makes sense for them to give away the tools (or their work enhancing the already-free tools) that enable more and better applications. An independent tool vendor is in a different position, and there have always been vendors with better tools, maybe for a specialized market, or maybe just going above and beyond what comes for free, which is what Mold tries to do. In other words, it’s clear to everyone now that the essential tools should be free, but surely not that all tools should be free!
    - latchkey 3y ago
      > In other words, it’s clear to everyone now that the essential tools should be free, but surely not that all tools should be free! Obviously not, since their business model changed.
  - simias 3y ago
    This is unfortunately still the norm in the FPGA world, which I think is a poor decision in the long term for Intel/Xilinx. I wanted to seriously get into FPGA dev a decade or so ago, I learned to write Verilog and everything but the tooling made me give up, it was too painful to deal with all the quirks and limitations of the free tools.
    - latchkey 3y ago
      It is possible to download and use the Xilinx tools for free. My company sells bare metal access to FPGA's and our customers do it all the time. I agree with the tooling being a nightmare though. It is a 80gb+ install that fails half the time.
      - sigsev_251 3y ago
        You forgot that it crashes in random times and that the text editor refuses to open files because sigasi can't be initialized
        latchkey 3y ago
        I didn't forget, I just didn't get past the install. ;-)
      - simias 3y ago
        I admit I'm mostly familiar with the Intel (formerly Altera) side. There are no restrictions at all on the Xilinx side? That's pretty neat.
        latchkey 3y ago
        You sign up on their website and click ok on the long eula nobody reads and then click download. So yea, there are probably restrictions, but they don't have a paywall in front of them. This isn't legal advice at all.
  - Veserv 3y ago
    They were charging $100/yr [1]. Literal peanuts. Actually, that is unfair to the peanuts, it is literal pocket lint. The average cost of a developer is more than $100/hr. mold needs to make you 0.05% (not 5%, 0.05%) more productive to directly pay for itself. If mold saves you 13 seconds a day in linking time it directly pays for itself. This ignores the knock on effects of reduced build time shortening the feedback cycle which completely dwarf the direct benefits. It is ridiculous that such dirt cheap pricing for tools is viewed as a problem. As we saw in a post yesterday [2], this is why they say there is no money is tools. [1] https://bluewhale.systems/ https://bluewhale.systems/ [2] https://news.ycombinator.com/item?id=36869747 https://news.ycombinator.com/item?id=36869747
    - latchkey 3y ago
      Only $100/yr? Likely that is the problem then. Who's going to bother filing a P.O. with their mega company for only that amount? It also wasn't paywalled, meaning tons of people probably just added it as a dependency in the CI and just ignored the license restrictions because it wasn't directly part of the shipped binary. There's no good way to enforce that.
      - orra 3y ago
        > and just ignored the license restrictions because it wasn't directly part of the shipped binary. There's no good way to enforce that. There's not anything to enforce. The AGPL allows you to run the application for any purpose. (If you modify the source, you have to make the modified source available to all users, including over the network users.)
        latchkey 3y ago
        Oh, you're right on that one. Kind of entertaining that the AGPL is all about linking, and this is the linker.
        account42 3y ago
        The GPL is all about linking. The AGPL is about extending what it means to distribute the software to SAAS-like uses.
  - cmgbhm 3y ago
    You had to buy C compiler on many operating systems. At least once upon a time, it came with another giant set of books.
    - latchkey 3y ago
      Codewarrior for the win! I used to hate all the times I would mess up a pointer and my whole machine would freeze up.
    - throwawaymobule 3y ago
      I am so glad GCC came and took over, even if I didn't have to live through this era. The standard choice being free and good (best, in many cases) really can't be overstated.
      - pjmlp 3y ago
        GCC was largely ignored until the day Sun introduced the concept of UNIX user and developer editions. Only then it started to gain momentum from people not willing to pay for Solaris Developer SDK. In any case, I bet people using free beer tools enjoy being paid for their work, so just maybe they should also think in giving some money to the authors of those tools.
Timon3 3y ago
Very happy to read about the license change! I hope they are able to earn money from the project, but the likelihood of being able to integrate it into any work projects is much higher with MIT licensing. If we do use it, I'll try to get our company to sponsor the project.
- kevin_thibedeau 3y ago
  The license on a linker shouldn't matter. It isn't injecting copyrighted code and there's already precedent for excepting trivial boilerplate in the GPL ecosystem so nothing in the generated binary should be affected by a copyleft license on the tooling. AGPL would only restrict deploying a privately modified linker via a network service which isn't a realistic scenario for a basic dev tool.
  - Timon3 3y ago
    Good luck convincing corporate lawyers that the license terms don't matter since we're just using it for linking. I don't know many (any?) that would risk it.
  - tantalic 3y ago
    While that is true, it requires a very specific understanding of both intellectual property law and the inner workings of development tooling that is pretty rare in practice. As such, companies are generally conservative in such decisions. Most organizations have a single list of licenses allowed for use rather than getting into specific use cases for specific licenses. These types of environments will generally limit uptake of copyleft tools. All that said, I'm not convinced the licensing is the issue here (although I wish them the best). We are in a world that has grown accustom to free development tools and building a commercially viable business in tooling is incredibly difficult. I'm always amazed by how many developers I know who make a living by creating software yet are unwilling to pay for software themselves.
    - tyg13 3y ago
      All of those companies have no issues using `ld` right? Binutils is GPL and has always been. Seems like a direct analogy.
dale_glass 3y ago
Mold is absolutely excellent work for modern systems. I've recently been trying to speed up our project builds, and found that linking is absolutely a huge bottleneck. I've got 24 cores * 2 threads to build on, and maybe 30% of that power goes unused because of the linker. I've made a previous attempt to build with mold but it didn't quite work at the time. I'll be giving it another try.
- sho_hn 3y ago
  We've also done some PoCs at work, and the total build time for our UI layer (complex C++/Qt stuff) dropped from 44-45 mins to 29 by going from lld to mold on a smaller test build machine.
- bogwog 3y ago
  Mold is amazing. I was playing around with O3DE some months ago, and tried switching to Mold to see if it could improve my build-run cycle times, and it absolutely did. I don't remember the exact numbers, but it was something crazy like multiple seconds with gold and lld, down to under a second with mold.
  - kaashif 3y ago
    Multiple seconds...I've worked on binaries that take 20 minutes to link. Having a ridiculously long cycle time massacres productivity and job satisfaction.
    - itsTyrion 3y ago
      TWENTY minutes? O_o what kinda software/binary was that if you don't mind me asking?
      - maccard 3y ago
        I'm not OP but I've worked on projects with similar link times. Large games that are one monolithic executable and have enormous debug information filed (sym or pdb depending on platform). Heres a good blog post [0]. [0] https://devblogs.microsoft.com/cppblog/improved-linker-fundamentals-in-visual-studio-2019/ https://devblogs.microsoft.com/cppblog/improved-linker-funda...
artemonster 3y ago
I wonder howa change to MIT license should improve situation? Means with AGPL adoption was low because…?
- placatedmayhem 3y ago
  I'm subject to a moratorium on AGPL software at work. Some legal departments forbid or highly restrict use of AGPL licenses. They are concerned the licenses' viral nature causing problems for their software products. Not that I agree with them, but, also, IANAL.
  - realharo 3y ago
    I'm guessing that's what the commercial license option was for.
    - anyoneamous 3y ago
      I'm sure it is - but that leaves the engineer with the calculation to do of "time this commercial tool will save me" versus "time/goodwill I will burn trying to get the purchase approved".
      - hermanradtke 3y ago
        This is also true of SaaS dev tools. There are plenty of ways to reduce friction. In this case, mold could have offered a 30 day commercial license to the company to demo the linker and see if the ROI was worth it.
  - wiz21c 3y ago
    Let's see that positively: with such a moratorium, we're less at risk of having some AGPL software used without respecting its licene terms :-)
- baq 3y ago
  moral of the story is tools don't sell regardless of license.
rurban 3y ago
make replaced by cmake, ouch. how to I get my -march=native -flto perf improvements in there easily? Would need at least 20 lines...
- gjvc 3y ago
  Try this on for size as a concrete example. (The %{notation} is due to the RPM .spec file syntax -- adjust as required.) argv=( ${CMAKE:-cmake3} ) argv+=( -S %{cmake_source_dir} ) argv+=( -B %{cmake_build_dir} ) argv+=( -G Ninja ) argv+=( -D CMAKE_CXX_FLAGS='-march=native -flto' ) argv+=( -D CMAKE_INSTALL_PREFIX=%{install_home} ) argv+=( -D CMAKE_EXE_LINKER_FLAGS="-Wl,-rpath=%{openssl_root}/lib" ) argv+=( -D OPENSSL_ROOT_DIR=%{openssl_root} ) "${argv[@]}"
- mhh__ 3y ago
  You should still be OK although I agree that CMake is really annoying to approach if you don't know the projects idioms particularly well e.g. there is a recurring bug in one of our builds where OMP initialization causes a deadlock, which can thus be disabled by not using openmp at cmake-time: finding how to do this when I went to disable it permanently took a good 20 minutes of guesswork because it's CMake magic versus make bullshit
- duped 3y ago
  You configure with -DCMAKE_CXX_FLAGS='-march=native -ftlo' like any other cmake build. Or you `-G'Unix Makefiles' and export CFLAGS/CXXFLAGS before you build it if you really want to use make.
KolmogorovComp 3y ago
Does someone know if this change of licence/business strategy is expected to expand to sold[0] (mold for macOS)? [0] https://github.com/bluewhalesystems/sold https://github.com/bluewhalesystems/sold
- bdcravens 3y ago
  At the very top of mold's README (my guess is no, it won't become OSS): > This repository contains a free version of the mold linker. If you are looking for a commercial version that supports macOS please visit the repository of the sold linker.
  - SmileyKeith 3y ago
    That has been there for a while so I think it's still an open question of if this change of strategy applies to that repo too
    - SmileyKeith 3y ago
      Looks like someone filed an issue about this https://github.com/bluewhalesystems/sold/issues/35 https://github.com/bluewhalesystems/sold/issues/35
- lathiat 3y ago
  Apple has a new parallel linker which may or may not be of interest : https://twitter.com/davidecci/status/1665835119331135488 https://twitter.com/davidecci/status/1665835119331135488
- KingLancelot 3y ago
  I don’t get why Apple doesn’t sponsor the project and make Mold the default linker in Xcode. Give him a stack of cash for his work and make all well with the Universe. It’d be so easy for them.
  - ChadNauseam 3y ago
thejosh 3y ago
Mold is great, here are some usecases I love: 1. Faster rust builds! [target.x86_64-unknown-linux-gnu] linker = "clang" rustflags = [ "-C", "link-arg=-fuse-ld=mold", "-C", "target-cpu=native" ] 2. Faster `makepkg` with ArchLinux, by adding "-fuse-ld=mold" to CFLAGS.
- forrestthewoods 3y ago
  What was the before/after on your Rust link times?
  - ripley12 3y ago
    About a year ago, I was seeing incremental builds go from ~8s to ~2.7s with Mold. Huge quality of life improvement. (fairly large Rust project, 24-core machine, Linux)
  - Measter 3y ago
    A quick and dirty comparison on my project: -- GNU Ld 2.31.1 >> cargo build --release Compiling mfl v0.1.0 (/mnt/d/Programming/Projects/Rust/mfl/crates/mfl) Finished release [optimized + debuginfo] target(s) in 10.14s -- LLD-14 >> cargo build --release Compiling mfl v0.1.0 (/mnt/d/Programming/Projects/Rust/mfl/crates/mfl) Finished release [optimized + debuginfo] target(s) in 6.20s -- Mold 2.0 >> cargo build --release Compiling mfl v0.1.0 (/mnt/d/Programming/Projects/Rust/mfl/crates/mfl) Finished release [optimized + debuginfo] target(s) in 6.02s I did the following for each test: cargo clean cargo build --release touch crates/mfl/src/main.rs cargo build --release With the timings coming from the second build. The project links in LLVM, and the tests were done under WSL1 on Windows 10 with the files on the Windows file system, which is how the project is developed in general.
  - aseipp 3y ago
    Personal anecdote: linking a debug build of buck2 (big Rust codebase) went from 30s to 3s for me. Pretty wonderful.
- rmdashrfstar 3y ago
mezobeli 3y ago
If it speeds up Rust compilation time, wow!
- sophacles 3y ago
  It doesn't. It speeds up rust linking time tho.
  - badrequest 3y ago
    Are there available benchmarks around how much the performance changes?
    - ripley12 3y ago
      It depends a lot on the project and your CPU. Incremental build (build, change 1 thing, rebuild) times are affected more than clean build times, because linking is a larger % of an incremental build. When I benchmarked it about a year ago (with a fairly large Rust project on a 24-core machine), incremental builds went from ~8s to ~2.7s.
deleted 3y ago
[deleted]
carterschonwald 3y ago
Does this mean macho/Darwin support might get back in?
wg0 3y ago
License changed from AGPL to MIT. But how (and why not) such a fine cratsman should be rewarded? Companies (maybe of all sizes) should allocate some funds to their top dependencies/tools or something and this should be listed on their main websites. More of a cultural norm I guess?
nu11ptr 3y ago
Very wise decision. I know in my own products/code I sometimes have to swallow the tough pill and admit that some things just aren't a good fit for monetization. The market speaks, unfortunately, and it is important to try not to fight it, but instead find something else the market rewards.
cogman10 3y ago
Anyone got any numbers/info on the impact to LTO optimizations? Some brief googling shows mold does support LTO, but is it as good/better than what you'll find in the LLVM/GCC linkers?
- KingLancelot 3y ago
  [dead]
- jcelerier 3y ago
  In the end it's the compiler which is being called by the linker to perform LTO, 99% of the time will be spent there
- psykotic 3y ago
  LTO for LLVM/clang and gcc is implemented by getting the compiler to emit internal compiler IR code rather than machine code to the object files. The linker's job is to call into the compilers at link time with the serialized IR code from the object files to produce machine code; the linker does not do the link-time optimization itself. Therefore LTO support in a linker is a pretty binary feature (does it support X compiler on Y platform?) without much of a "good/better" gradation. And when it comes to that, mold implements LTO support for both gcc and LLVM on Unix-like systems.
sixthDot 3y ago
It still does not support .init_array / .fini_array sections. Too bad I'd like to use it.
- glandium 3y ago
  Wait, what? You mean it doesn't fill the DT_INIT_ARRAY/DT_INIT_ARRAYSZ values in PT_DYNAMIC?
hgs3 3y ago
I'm curious about the license change? This is an executable is it not? Invoking it as a separate process does not require you make the software calling it GPL so switching to MIT should have no affect in the common case. If the authors really wanted a more permissive license, then instead of relicensing from AGPL to MIT they should have relicensed from AGPL to AGPL with linking exception. An example of a project that is GPL with linking exception is libgit2 [1]. This licensing is more permissive but still permits the author to sell commercial licenses to those making closed-source code changes. [1] https://github.com/libgit2/libgit2#license https://github.com/libgit2/libgit2#license
- hobofan 3y ago
  > This licensing is more permissive but still permits the author to sell commercial licenses to those making closed-source code changes. I think the point is that the authors don't want want to continue selling licenses, as it wasn't worth the hassle. I guess `sold`, the macOS version is an exception.
  - hgs3 3y ago
    > it wasn't worth the hassle If selling licenses is a hassle, then that indicates a problem with the open source ecosystem as GitHub and other code hosting websites should offer monetization tools for selling closed-source licenses directly from their web interface. I'm talking legal forms, templates, payment processors, and product tracking. Selling licenses should be easy, not a hassle. [1] https://github.com/rui314/mold/releases/tag/v2.0.0 https://github.com/rui314/mold/releases/tag/v2.0.0
    - KRAKRISMOTT 3y ago
      The MPL or the BSL would be a better license. The best would be the MPL with something like Facebook's "700 mil mau" and above requiring a support contract. The Mangas corps benefit the most from mold given the inherent size of their C++ codebases.
winrid 3y ago
I love Mold. Got my Rust debug builds from 15 seconds to 2 seconds on one project.
Night_Thastus 3y ago
As a C++ dev, this kind of project makes me dream. I wish I could use things like this in my day-to-day. Sadly, stuck on very old OSs and toolchains. And you can forget about ever using Clang! :(
_a_a_a_ 3y ago
Over many years I've come across several discussions about fast linkers and how compile times sped up so much by replacing one linker with a faster one, but I've never found out what about them makes them normally so slow. Can anyone shed some light please?
- ripley12 3y ago
  This isn't the whole story, but linking is CPU-intensive and older linkers are mostly single-threaded. A lot of the performance gains come from doing work in parallel, which makes for a big improvement on beefy modern multicore CPUs. Rui's given some good talks about Mold if you want more info: https://www.youtube.com/watch?v=hAt3kCalE0Y https://www.youtube.com/watch?v=hAt3kCalE0Y
  - glandium 3y ago
    Even single-threaded, modern linkers (lld, mold, even gold) are faster than BFD ld, which is notoriously slow, and sadly still the default you get on Linux.
- JonChesterfield 3y ago
  Yep. A linker in the best case would run as fast as cat. Paste the binaries together, done. Disk I/O was a problem back when we used spinning rust but less so now. What takes time is rewriting stuff as you go. Running the relocation tables to insert addresses into the code is cheap. Deadstripping sections is fairly cheap, deadstripping individual basic blocks within functions takes a lot more analysis and thus time. Deduplicating constant strings is a good idea but involves streaming them all into a hashtable of some sort. Maybe you want them to share common suffixes, more work. Deduplicating, deadstripping, rewriting debug information takes time. Debug builds can feature many gigabytes of dwarf to rewrite. Oddly enough that the linker is scriptable, as in you can give it a program that it interprets, doesn't seem to be a significant cost. Probably because the script in question is quite short and somewhat limited in functionality. Historically lld was very fast because it didn't bother doing any of the debug munging or other deduplication. Lld ran fast but the output binary was big. I'm several years out of the linker performance game now so don't know the current status. In particular I don't know where mold or lld are in terms of quality of output vs their own performance.
ShadowBanThis01 3y ago
Is what?
jakswa 3y ago
This linker noticeably improves rust development happiness on an exploratory, chunky repo of mine that is trying to be a big ole web monolith (uses SeaORM and axum/tokio). You don't want to know the size of my `target` directory, but incremental builds are snappier!
- mmastrac 3y ago
  I need to play around with mold: 15:55 $ du -Hs --si target/ 11G target/
  - jakswa 3y ago
    just in case I confused: i'm not sure mold helps with the size of that directory :D. I was commenting on how big my rust repo is really, just saying that mold seems to help big builds like mine
zX41ZdbW 3y ago
I'm amazed at how quickly the author responds to requests: https://github.com/rui314/mold/issues/1057 https://github.com/rui314/mold/issues/1057 From the report to the fix in less than two days. I'm not sure how competitive it will be with lld, especially if we consider ThinLTO (which takes multiple minutes on 64-core machine) - it can make the advantages of mold insignificant.
- speed_spread 3y ago
  mold will always win over lld, even if only for the much cooler name.
- account42 3y ago
  > I'm not sure how competitive it will be with lld, especially if we consider ThinLTO (which takes multiple minutes on 64-core machine) - it can make the advantages of mold insignificant. Mold is focused on (incremental) development builds where LTO is probably not what you want anyway. For actual release builds you shouldn't really care that much about the build time.
stevefan1999 3y ago
Still, the lack of Windows MSVC support makes us unable to employ Mold. MinGW build maybe, but I don't think Mold is even able to produce PE now.
- delta_p_delta_x 3y ago
  According to the developer, he has also written lld-link.exe[1] (i.e. lld that accepts link.exe flags for compatibility), which is already significantly faster than link.exe. [1]: https://github.com/rui314/mold/issues/190#:~:text=I%27ve%20already%20wrote%20lld%20for%20Windows%20(that%27s%20my%20first%20liner) https://github.com/rui314/mold/issues/190#:~:text=I%27ve%20a...

430 points by fomine3 3y ago

I had forgotten that it was a fast linker: > Mold 2.0.0 is a new major release of our high-speed linker. With this release, we've transitioned our license from AGPL to MIT, aiming to expand the user base of our linker. This was not an easy decision, as those who have been following our progress know that we've been attempting to monetize our product through an AGPL/commercial license dual-licensing scheme. Unfortunately, this approach didn't meet our expectations. The license change represents our acceptance of this reality. We don't want to persist with a strategy that didn't work well.

latchkey 3y ago
Anyone remember having to pay for cc on Solaris? [0] It was horrible and a terrible way to treat developers who are writing software for your OS! We have been conditioned for a very long time to not need to pay for low level developer tools and to pay for support instead. I'm surprised they even tried to license it like that. [0] https://unix.stackexchange.com/questions/12731/usr-ucb-cc-language-optional-software-package-not-installed https://unix.stackexchange.com/questions/12731/usr-ucb-cc-la...
- tingletech 3y ago
  At work in the 90s I was allowed to buy a brand new sparc workstation with a shrinkwrap compiler (and shrinkwrap sybase). One of the first things I did was compile gcc so I could install the whole gnu world.
  - latchkey 3y ago
    Exactly! I begged someone random for a gcc tarball.
    - dmvdoug 3y ago
      Now I am imagining you panhandling on the sidewalk, stopping random strangers and shaking slightly: “hey man, can you spare a gcc tarball?”
  - jsrcout 3y ago
    They did the same at my first job out of college (Sun based company). It was my first introduction to free software. That was circa 1990... it's amazing that gcc is still going strong.
- wrs 3y ago
  There’s a distinction between the maker of the OS/hardware and an independent vendor trying to monetize the tools. The OS/hardware maker’s primary interest is in selling more OS or hardware, so it makes sense for them to give away the tools (or their work enhancing the already-free tools) that enable more and better applications. An independent tool vendor is in a different position, and there have always been vendors with better tools, maybe for a specialized market, or maybe just going above and beyond what comes for free, which is what Mold tries to do. In other words, it’s clear to everyone now that the essential tools should be free, but surely not that all tools should be free!
  - latchkey 3y ago
    > In other words, it’s clear to everyone now that the essential tools should be free, but surely not that all tools should be free! Obviously not, since their business model changed.
- simias 3y ago
  This is unfortunately still the norm in the FPGA world, which I think is a poor decision in the long term for Intel/Xilinx. I wanted to seriously get into FPGA dev a decade or so ago, I learned to write Verilog and everything but the tooling made me give up, it was too painful to deal with all the quirks and limitations of the free tools.
  - latchkey 3y ago
    It is possible to download and use the Xilinx tools for free. My company sells bare metal access to FPGA's and our customers do it all the time. I agree with the tooling being a nightmare though. It is a 80gb+ install that fails half the time.
    - sigsev_251 3y ago
      You forgot that it crashes in random times and that the text editor refuses to open files because sigasi can't be initialized
      - latchkey 3y ago
        I didn't forget, I just didn't get past the install. ;-)
    - simias 3y ago
      I admit I'm mostly familiar with the Intel (formerly Altera) side. There are no restrictions at all on the Xilinx side? That's pretty neat.
      - latchkey 3y ago
        You sign up on their website and click ok on the long eula nobody reads and then click download. So yea, there are probably restrictions, but they don't have a paywall in front of them. This isn't legal advice at all.
- Veserv 3y ago
  They were charging $100/yr [1]. Literal peanuts. Actually, that is unfair to the peanuts, it is literal pocket lint. The average cost of a developer is more than $100/hr. mold needs to make you 0.05% (not 5%, 0.05%) more productive to directly pay for itself. If mold saves you 13 seconds a day in linking time it directly pays for itself. This ignores the knock on effects of reduced build time shortening the feedback cycle which completely dwarf the direct benefits. It is ridiculous that such dirt cheap pricing for tools is viewed as a problem. As we saw in a post yesterday [2], this is why they say there is no money is tools. [1] https://bluewhale.systems/ https://bluewhale.systems/ [2] https://news.ycombinator.com/item?id=36869747 https://news.ycombinator.com/item?id=36869747
  - latchkey 3y ago
    Only $100/yr? Likely that is the problem then. Who's going to bother filing a P.O. with their mega company for only that amount? It also wasn't paywalled, meaning tons of people probably just added it as a dependency in the CI and just ignored the license restrictions because it wasn't directly part of the shipped binary. There's no good way to enforce that.
    - orra 3y ago
      > and just ignored the license restrictions because it wasn't directly part of the shipped binary. There's no good way to enforce that. There's not anything to enforce. The AGPL allows you to run the application for any purpose. (If you modify the source, you have to make the modified source available to all users, including over the network users.)
      - latchkey 3y ago
        Oh, you're right on that one. Kind of entertaining that the AGPL is all about linking, and this is the linker.
        account42 3y ago
        The GPL is all about linking. The AGPL is about extending what it means to distribute the software to SAAS-like uses.
- cmgbhm 3y ago
  You had to buy C compiler on many operating systems. At least once upon a time, it came with another giant set of books.
  - latchkey 3y ago
    Codewarrior for the win! I used to hate all the times I would mess up a pointer and my whole machine would freeze up.
  - throwawaymobule 3y ago
    I am so glad GCC came and took over, even if I didn't have to live through this era. The standard choice being free and good (best, in many cases) really can't be overstated.
    - pjmlp 3y ago
      GCC was largely ignored until the day Sun introduced the concept of UNIX user and developer editions. Only then it started to gain momentum from people not willing to pay for Solaris Developer SDK. In any case, I bet people using free beer tools enjoy being paid for their work, so just maybe they should also think in giving some money to the authors of those tools.

Timon3 3y ago

Very happy to read about the license change! I hope they are able to earn money from the project, but the likelihood of being able to integrate it into any work projects is much higher with MIT licensing. If we do use it, I'll try to get our company to sponsor the project.

kevin_thibedeau 3y ago
The license on a linker shouldn't matter. It isn't injecting copyrighted code and there's already precedent for excepting trivial boilerplate in the GPL ecosystem so nothing in the generated binary should be affected by a copyleft license on the tooling. AGPL would only restrict deploying a privately modified linker via a network service which isn't a realistic scenario for a basic dev tool.
- Timon3 3y ago
  Good luck convincing corporate lawyers that the license terms don't matter since we're just using it for linking. I don't know many (any?) that would risk it.
- tantalic 3y ago
  While that is true, it requires a very specific understanding of both intellectual property law and the inner workings of development tooling that is pretty rare in practice. As such, companies are generally conservative in such decisions. Most organizations have a single list of licenses allowed for use rather than getting into specific use cases for specific licenses. These types of environments will generally limit uptake of copyleft tools. All that said, I'm not convinced the licensing is the issue here (although I wish them the best). We are in a world that has grown accustom to free development tools and building a commercially viable business in tooling is incredibly difficult. I'm always amazed by how many developers I know who make a living by creating software yet are unwilling to pay for software themselves.
  - tyg13 3y ago
    All of those companies have no issues using `ld` right? Binutils is GPL and has always been. Seems like a direct analogy.

dale_glass 3y ago

Mold is absolutely excellent work for modern systems. I've recently been trying to speed up our project builds, and found that linking is absolutely a huge bottleneck. I've got 24 cores * 2 threads to build on, and maybe 30% of that power goes unused because of the linker. I've made a previous attempt to build with mold but it didn't quite work at the time. I'll be giving it another try.

sho_hn 3y ago
We've also done some PoCs at work, and the total build time for our UI layer (complex C++/Qt stuff) dropped from 44-45 mins to 29 by going from lld to mold on a smaller test build machine.
bogwog 3y ago
Mold is amazing. I was playing around with O3DE some months ago, and tried switching to Mold to see if it could improve my build-run cycle times, and it absolutely did. I don't remember the exact numbers, but it was something crazy like multiple seconds with gold and lld, down to under a second with mold.
- kaashif 3y ago
  Multiple seconds...I've worked on binaries that take 20 minutes to link. Having a ridiculously long cycle time massacres productivity and job satisfaction.
  - itsTyrion 3y ago
    TWENTY minutes? O_o what kinda software/binary was that if you don't mind me asking?
    - maccard 3y ago
      I'm not OP but I've worked on projects with similar link times. Large games that are one monolithic executable and have enormous debug information filed (sym or pdb depending on platform). Heres a good blog post [0]. [0] https://devblogs.microsoft.com/cppblog/improved-linker-fundamentals-in-visual-studio-2019/ https://devblogs.microsoft.com/cppblog/improved-linker-funda...

artemonster 3y ago

I wonder howa change to MIT license should improve situation? Means with AGPL adoption was low because…?

placatedmayhem 3y ago
I'm subject to a moratorium on AGPL software at work. Some legal departments forbid or highly restrict use of AGPL licenses. They are concerned the licenses' viral nature causing problems for their software products. Not that I agree with them, but, also, IANAL.
- realharo 3y ago
  I'm guessing that's what the commercial license option was for.
  - anyoneamous 3y ago
    I'm sure it is - but that leaves the engineer with the calculation to do of "time this commercial tool will save me" versus "time/goodwill I will burn trying to get the purchase approved".
    - hermanradtke 3y ago
      This is also true of SaaS dev tools. There are plenty of ways to reduce friction. In this case, mold could have offered a 30 day commercial license to the company to demo the linker and see if the ROI was worth it.
- wiz21c 3y ago
  Let's see that positively: with such a moratorium, we're less at risk of having some AGPL software used without respecting its licene terms :-)
baq 3y ago
moral of the story is tools don't sell regardless of license.

rurban 3y ago

make replaced by cmake, ouch. how to I get my -march=native -flto perf improvements in there easily? Would need at least 20 lines...

gjvc 3y ago
Try this on for size as a concrete example. (The %{notation} is due to the RPM .spec file syntax -- adjust as required.) argv=( ${CMAKE:-cmake3} ) argv+=( -S %{cmake_source_dir} ) argv+=( -B %{cmake_build_dir} ) argv+=( -G Ninja ) argv+=( -D CMAKE_CXX_FLAGS='-march=native -flto' ) argv+=( -D CMAKE_INSTALL_PREFIX=%{install_home} ) argv+=( -D CMAKE_EXE_LINKER_FLAGS="-Wl,-rpath=%{openssl_root}/lib" ) argv+=( -D OPENSSL_ROOT_DIR=%{openssl_root} ) "${argv[@]}"
mhh__ 3y ago
You should still be OK although I agree that CMake is really annoying to approach if you don't know the projects idioms particularly well e.g. there is a recurring bug in one of our builds where OMP initialization causes a deadlock, which can thus be disabled by not using openmp at cmake-time: finding how to do this when I went to disable it permanently took a good 20 minutes of guesswork because it's CMake magic versus make bullshit
duped 3y ago
You configure with -DCMAKE_CXX_FLAGS='-march=native -ftlo' like any other cmake build. Or you `-G'Unix Makefiles' and export CFLAGS/CXXFLAGS before you build it if you really want to use make.

KolmogorovComp 3y ago

Does someone know if this change of licence/business strategy is expected to expand to sold[0] (mold for macOS)? [0] https://github.com/bluewhalesystems/sold https://github.com/bluewhalesystems/sold

bdcravens 3y ago
At the very top of mold's README (my guess is no, it won't become OSS): > This repository contains a free version of the mold linker. If you are looking for a commercial version that supports macOS please visit the repository of the sold linker.
- SmileyKeith 3y ago
  That has been there for a while so I think it's still an open question of if this change of strategy applies to that repo too
  - SmileyKeith 3y ago
    Looks like someone filed an issue about this https://github.com/bluewhalesystems/sold/issues/35 https://github.com/bluewhalesystems/sold/issues/35
lathiat 3y ago
Apple has a new parallel linker which may or may not be of interest : https://twitter.com/davidecci/status/1665835119331135488 https://twitter.com/davidecci/status/1665835119331135488
KingLancelot 3y ago
I don’t get why Apple doesn’t sponsor the project and make Mold the default linker in Xcode. Give him a stack of cash for his work and make all well with the Universe. It’d be so easy for them.
- ChadNauseam 3y ago

thejosh 3y ago

Mold is great, here are some usecases I love: 1. Faster rust builds! [target.x86_64-unknown-linux-gnu] linker = "clang" rustflags = [ "-C", "link-arg=-fuse-ld=mold", "-C", "target-cpu=native" ] 2. Faster `makepkg` with ArchLinux, by adding "-fuse-ld=mold" to CFLAGS.

forrestthewoods 3y ago
What was the before/after on your Rust link times?
- ripley12 3y ago
  About a year ago, I was seeing incremental builds go from ~8s to ~2.7s with Mold. Huge quality of life improvement. (fairly large Rust project, 24-core machine, Linux)
- Measter 3y ago
  A quick and dirty comparison on my project: -- GNU Ld 2.31.1 >> cargo build --release Compiling mfl v0.1.0 (/mnt/d/Programming/Projects/Rust/mfl/crates/mfl) Finished release [optimized + debuginfo] target(s) in 10.14s -- LLD-14 >> cargo build --release Compiling mfl v0.1.0 (/mnt/d/Programming/Projects/Rust/mfl/crates/mfl) Finished release [optimized + debuginfo] target(s) in 6.20s -- Mold 2.0 >> cargo build --release Compiling mfl v0.1.0 (/mnt/d/Programming/Projects/Rust/mfl/crates/mfl) Finished release [optimized + debuginfo] target(s) in 6.02s I did the following for each test: cargo clean cargo build --release touch crates/mfl/src/main.rs cargo build --release With the timings coming from the second build. The project links in LLVM, and the tests were done under WSL1 on Windows 10 with the files on the Windows file system, which is how the project is developed in general.
- aseipp 3y ago
  Personal anecdote: linking a debug build of buck2 (big Rust codebase) went from 30s to 3s for me. Pretty wonderful.
rmdashrfstar 3y ago

mezobeli 3y ago

If it speeds up Rust compilation time, wow!

sophacles 3y ago
It doesn't. It speeds up rust linking time tho.
- badrequest 3y ago
  Are there available benchmarks around how much the performance changes?
  - ripley12 3y ago
    It depends a lot on the project and your CPU. Incremental build (build, change 1 thing, rebuild) times are affected more than clean build times, because linking is a larger % of an incremental build. When I benchmarked it about a year ago (with a fairly large Rust project on a 24-core machine), incremental builds went from ~8s to ~2.7s.

deleted 3y ago

[deleted]

carterschonwald 3y ago

Does this mean macho/Darwin support might get back in?

wg0 3y ago

License changed from AGPL to MIT. But how (and why not) such a fine cratsman should be rewarded? Companies (maybe of all sizes) should allocate some funds to their top dependencies/tools or something and this should be listed on their main websites. More of a cultural norm I guess?

nu11ptr 3y ago

Very wise decision. I know in my own products/code I sometimes have to swallow the tough pill and admit that some things just aren't a good fit for monetization. The market speaks, unfortunately, and it is important to try not to fight it, but instead find something else the market rewards.

cogman10 3y ago

Anyone got any numbers/info on the impact to LTO optimizations? Some brief googling shows mold does support LTO, but is it as good/better than what you'll find in the LLVM/GCC linkers?

KingLancelot 3y ago
[dead]
jcelerier 3y ago
In the end it's the compiler which is being called by the linker to perform LTO, 99% of the time will be spent there
psykotic 3y ago
LTO for LLVM/clang and gcc is implemented by getting the compiler to emit internal compiler IR code rather than machine code to the object files. The linker's job is to call into the compilers at link time with the serialized IR code from the object files to produce machine code; the linker does not do the link-time optimization itself. Therefore LTO support in a linker is a pretty binary feature (does it support X compiler on Y platform?) without much of a "good/better" gradation. And when it comes to that, mold implements LTO support for both gcc and LLVM on Unix-like systems.

sixthDot 3y ago

It still does not support .init_array / .fini_array sections. Too bad I'd like to use it.

glandium 3y ago
Wait, what? You mean it doesn't fill the DT_INIT_ARRAY/DT_INIT_ARRAYSZ values in PT_DYNAMIC?

hgs3 3y ago

I'm curious about the license change? This is an executable is it not? Invoking it as a separate process does not require you make the software calling it GPL so switching to MIT should have no affect in the common case. If the authors really wanted a more permissive license, then instead of relicensing from AGPL to MIT they should have relicensed from AGPL to AGPL with linking exception. An example of a project that is GPL with linking exception is libgit2 [1]. This licensing is more permissive but still permits the author to sell commercial licenses to those making closed-source code changes. [1] https://github.com/libgit2/libgit2#license https://github.com/libgit2/libgit2#license

hobofan 3y ago
> This licensing is more permissive but still permits the author to sell commercial licenses to those making closed-source code changes. I think the point is that the authors don't want want to continue selling licenses, as it wasn't worth the hassle. I guess `sold`, the macOS version is an exception.
- hgs3 3y ago
  > it wasn't worth the hassle If selling licenses is a hassle, then that indicates a problem with the open source ecosystem as GitHub and other code hosting websites should offer monetization tools for selling closed-source licenses directly from their web interface. I'm talking legal forms, templates, payment processors, and product tracking. Selling licenses should be easy, not a hassle. [1] https://github.com/rui314/mold/releases/tag/v2.0.0 https://github.com/rui314/mold/releases/tag/v2.0.0
  - KRAKRISMOTT 3y ago
    The MPL or the BSL would be a better license. The best would be the MPL with something like Facebook's "700 mil mau" and above requiring a support contract. The Mangas corps benefit the most from mold given the inherent size of their C++ codebases.

winrid 3y ago

I love Mold. Got my Rust debug builds from 15 seconds to 2 seconds on one project.

Night_Thastus 3y ago

As a C++ dev, this kind of project makes me dream. I wish I could use things like this in my day-to-day. Sadly, stuck on very old OSs and toolchains. And you can forget about ever using Clang! :(

_a_a_a_ 3y ago

Over many years I've come across several discussions about fast linkers and how compile times sped up so much by replacing one linker with a faster one, but I've never found out what about them makes them normally so slow. Can anyone shed some light please?

ripley12 3y ago
This isn't the whole story, but linking is CPU-intensive and older linkers are mostly single-threaded. A lot of the performance gains come from doing work in parallel, which makes for a big improvement on beefy modern multicore CPUs. Rui's given some good talks about Mold if you want more info: https://www.youtube.com/watch?v=hAt3kCalE0Y https://www.youtube.com/watch?v=hAt3kCalE0Y
- glandium 3y ago
  Even single-threaded, modern linkers (lld, mold, even gold) are faster than BFD ld, which is notoriously slow, and sadly still the default you get on Linux.
JonChesterfield 3y ago
Yep. A linker in the best case would run as fast as cat. Paste the binaries together, done. Disk I/O was a problem back when we used spinning rust but less so now. What takes time is rewriting stuff as you go. Running the relocation tables to insert addresses into the code is cheap. Deadstripping sections is fairly cheap, deadstripping individual basic blocks within functions takes a lot more analysis and thus time. Deduplicating constant strings is a good idea but involves streaming them all into a hashtable of some sort. Maybe you want them to share common suffixes, more work. Deduplicating, deadstripping, rewriting debug information takes time. Debug builds can feature many gigabytes of dwarf to rewrite. Oddly enough that the linker is scriptable, as in you can give it a program that it interprets, doesn't seem to be a significant cost. Probably because the script in question is quite short and somewhat limited in functionality. Historically lld was very fast because it didn't bother doing any of the debug munging or other deduplication. Lld ran fast but the output binary was big. I'm several years out of the linker performance game now so don't know the current status. In particular I don't know where mold or lld are in terms of quality of output vs their own performance.

ShadowBanThis01 3y ago

Is what?

jakswa 3y ago

This linker noticeably improves rust development happiness on an exploratory, chunky repo of mine that is trying to be a big ole web monolith (uses SeaORM and axum/tokio). You don't want to know the size of my `target` directory, but incremental builds are snappier!

mmastrac 3y ago
I need to play around with mold: 15:55 $ du -Hs --si target/ 11G target/
- jakswa 3y ago
  just in case I confused: i'm not sure mold helps with the size of that directory :D. I was commenting on how big my rust repo is really, just saying that mold seems to help big builds like mine

zX41ZdbW 3y ago

I'm amazed at how quickly the author responds to requests: https://github.com/rui314/mold/issues/1057 https://github.com/rui314/mold/issues/1057 From the report to the fix in less than two days. I'm not sure how competitive it will be with lld, especially if we consider ThinLTO (which takes multiple minutes on 64-core machine) - it can make the advantages of mold insignificant.

speed_spread 3y ago
mold will always win over lld, even if only for the much cooler name.
account42 3y ago
> I'm not sure how competitive it will be with lld, especially if we consider ThinLTO (which takes multiple minutes on 64-core machine) - it can make the advantages of mold insignificant. Mold is focused on (incremental) development builds where LTO is probably not what you want anyway. For actual release builds you shouldn't really care that much about the build time.

stevefan1999 3y ago

Still, the lack of Windows MSVC support makes us unable to employ Mold. MinGW build maybe, but I don't think Mold is even able to produce PE now.

delta_p_delta_x 3y ago
According to the developer, he has also written lld-link.exe[1] (i.e. lld that accepts link.exe flags for compatibility), which is already significantly faster than link.exe. [1]: https://github.com/rui314/mold/issues/190#:~:text=I%27ve%20already%20wrote%20lld%20for%20Windows%20(that%27s%20my%20first%20liner) https://github.com/rui314/mold/issues/190#:~:text=I%27ve%20a...