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Probably not, or they'd just be written in Java.

by dymk 4y ago

mhh__ 4y ago
There is more to performance than allocating memory. In fact some very performance-centric codebases do use a GC like unreal engine. On the subject of games it always makes me chuckle when I see people complaining about garbage collection but then having 20 calls to malloc in their hot loop. All memory allocation is slow and not necessarily bounded. I have written code that uses SoA, cache aware metaprogramming, inline asm, SIMD etc, with a GC because I knew I didn't need to allocate often. On the subject of Java, I'm no fan of it but lots of projects would probably be fine - probably not quite as fast, but not horrifically so. On hackernews we only discuss extremely careful or expertly written code whereas in real life a lot people use C++ because it's what they got hammered into them at university 20 years ago as the fast language. For example a lot of engineering and finance codebases are written in a very bad style of C++ code that would be improved by not having the programmers worry about memory too much - infrastructural code is more subtle, but most code serves a direct purpose like implementing some model. In these cases memory allocation is merely a means to an end rather than part of some grand strategy (i.e. it's not like writing a library)
- dataangel 4y ago
  Unreal Engine mostly uses GC for game world objects. Only C++ classes that inherit from a special base class and opt-in are subject to GC. If they used GC for everything the performance would be much worse.
  - mhh__ 4y ago
    Sure, but I'm saying that most C++ code in the wild is probably firmly in the former category.
- skl131313 4y ago
  I love when people bring up that UE has a GC, if it was written in Java, do you think they would have built a GC on top of Java's GC? I guess it depends on the GC at that point, 20 mallocs isn't a lot but like the GC in D, it pauses all threads to do it's collection when you allocate. There's also a few games that use C# that have a really bad stutter because of the GC. There's nothing they can do about that though.

Probably not, or they'd just be written in Java.

by dymk 4y ago

Probably not, or they'd just be written in Java.

There is more to performance than allocating memory. In fact some very performance-centric codebases do use a GC like unreal engine. On the subject of games it always makes me chuckle when I see people complaining about garbage collection but then having 20 calls to malloc in their hot loop. All memory allocation is slow and not necessarily bounded. I have written code that uses SoA, cache aware metaprogramming, inline asm, SIMD etc, with a GC because I knew I didn't need to allocate often. On the subject of Java, I'm no fan of it but lots of projects would probably be fine - probably not quite as fast, but not horrifically so. On hackernews we only discuss extremely careful or expertly written code whereas in real life a lot people use C++ because it's what they got hammered into them at university 20 years ago as the fast language. For example a lot of engineering and finance codebases are written in a very bad style of C++ code that would be improved by not having the programmers worry about memory too much - infrastructural code is more subtle, but most code serves a direct purpose like implementing some model. In these cases memory allocation is merely a means to an end rather than part of some grand strategy (i.e. it's not like writing a library)

dataangel 4y ago
Unreal Engine mostly uses GC for game world objects. Only C++ classes that inherit from a special base class and opt-in are subject to GC. If they used GC for everything the performance would be much worse.
- mhh__ 4y ago
  Sure, but I'm saying that most C++ code in the wild is probably firmly in the former category.
skl131313 4y ago
I love when people bring up that UE has a GC, if it was written in Java, do you think they would have built a GC on top of Java's GC? I guess it depends on the GC at that point, 20 mallocs isn't a lot but like the GC in D, it pauses all threads to do it's collection when you allocate. There's also a few games that use C# that have a really bad stutter because of the GC. There's nothing they can do about that though.