4 ms·

Frankly, I think a lot of the people currently working with C/C++ are avoiding Go because of the garbage collector. You can't trust a garbage collector; you do

by kbuck 14y ago

Frankly, I think a lot of the people currently working with C/C++ are avoiding Go because of the garbage collector. You can't trust a garbage collector; you don't know when it will run, how long it'll take, or how quickly it will free the memory you used. C/C++ programmers are used to having complete control over all of this. Sure, you could familiarize yourself with the internals of whichever GC you're working with, but at that point you might as well have invested the same amount of time writing the program in a language without a GC.

wting 14y ago
That's one of the reasons Rust appealed to me more than Go. Go has a global mark and sweep GC. OTOH Rust has a thread local, optional GC.
dualogy 14y ago
> You can't trust a garbage collector; you don't know when it will run, how long it'll take, or how quickly it will free the memory you used You can certainly control the GC somewhat. For example, disable unpredictable automatic GC and run GC yourself at a more opportune time, or never (if the program terminates before consuming all swap space of course). I have one app where I loop continously and invoke the GC every second. Why so often -- crazy, right? No because the "garbage" generated over that second --thanks to some memory-aware development practices-- is minimal, so the GC call will typically return in way under 1ms. Of course that's a meaningless number without app context and other numbers, but you do get some control. Basically Go gives you both philosophies. On one hand, you can auto-GC and never worry about mem or perf and simply "code out" your need, like you would in Java/C#/Python etc. Or, you can carefully design data structures and operations with allocations and GC (or supressed/non-existing GC) in mind. Sure, you don't get direct access to malloc()/free(), but implicitly (via Go's data structures, struct values vs pointers etc etc) you have a great deal more control over memory accesses, allocations etc.
blt 14y ago
Yeah, I've had to push code down from our C# layer to our C++ layer on more than one occasion because the GC wasn't freeing memory promptly enough. I guess I don't know the GC well enough to nudge it in the right direction - but now I don't trust it and I plan to keep all high performance stuff in the native layer. I'd like to hear from someone who figured out how to tame the GC in applications where lots of new data is created and destroyed quickly.
jff 14y ago
I'm going to make the argument that a lot, if not the majority, of C/C++ programmers don't need complete control over memory management. I think in many cases (not OS, not real-time), saying "but I need absolute control over memory management so I can optimize!" is the equivalent of "I write everything in hand-coded assembly because it's more efficient". It's probably not, the machine can probably handle it better, and you're missing out on useful functionality. You know what happens when I allocate and free memory myself? I generally end up with either a leak or a double-free, and I doubt I'm such a terrible programmer that I'm the only one like that.
- p0nce 14y ago
  False dichotomy. If you use RAII, exceptions, and smart pointers in C++ there will be no leaks, no double-free, and not even a need for a GC. I know it is difficult to make a point on the Internet, but resource leaks really are a solved problem in C++.
  - jff 14y ago
    Yes, but then you're stuck using C++, RAII, and exceptions. Let's not even get into which smart pointer you should use--a Googler I know has recounted stories of massive internal mailing list arguments over exactly which of the half-dozen smart pointer implementations they should be using.
    - p0nce 14y ago
      So, because C++ has imaginary problems, we should all switch to a language that solve them, while being worse at all other things that matters (you know, like code generation)?

by kbuck 14y ago

wting 14y ago

That's one of the reasons Rust appealed to me more than Go. Go has a global mark and sweep GC. OTOH Rust has a thread local, optional GC.

dualogy 14y ago

> You can't trust a garbage collector; you don't know when it will run, how long it'll take, or how quickly it will free the memory you used You can certainly control the GC somewhat. For example, disable unpredictable automatic GC and run GC yourself at a more opportune time, or never (if the program terminates before consuming all swap space of course). I have one app where I loop continously and invoke the GC every second. Why so often -- crazy, right? No because the "garbage" generated over that second --thanks to some memory-aware development practices-- is minimal, so the GC call will typically return in way under 1ms. Of course that's a meaningless number without app context and other numbers, but you do get some control. Basically Go gives you both philosophies. On one hand, you can auto-GC and never worry about mem or perf and simply "code out" your need, like you would in Java/C#/Python etc. Or, you can carefully design data structures and operations with allocations and GC (or supressed/non-existing GC) in mind. Sure, you don't get direct access to malloc()/free(), but implicitly (via Go's data structures, struct values vs pointers etc etc) you have a great deal more control over memory accesses, allocations etc.

blt 14y ago

Yeah, I've had to push code down from our C# layer to our C++ layer on more than one occasion because the GC wasn't freeing memory promptly enough. I guess I don't know the GC well enough to nudge it in the right direction - but now I don't trust it and I plan to keep all high performance stuff in the native layer. I'd like to hear from someone who figured out how to tame the GC in applications where lots of new data is created and destroyed quickly.

jff 14y ago

I'm going to make the argument that a lot, if not the majority, of C/C++ programmers don't need complete control over memory management. I think in many cases (not OS, not real-time), saying "but I need absolute control over memory management so I can optimize!" is the equivalent of "I write everything in hand-coded assembly because it's more efficient". It's probably not, the machine can probably handle it better, and you're missing out on useful functionality. You know what happens when I allocate and free memory myself? I generally end up with either a leak or a double-free, and I doubt I'm such a terrible programmer that I'm the only one like that.

p0nce 14y ago
False dichotomy. If you use RAII, exceptions, and smart pointers in C++ there will be no leaks, no double-free, and not even a need for a GC. I know it is difficult to make a point on the Internet, but resource leaks really are a solved problem in C++.
- jff 14y ago
  Yes, but then you're stuck using C++, RAII, and exceptions. Let's not even get into which smart pointer you should use--a Googler I know has recounted stories of massive internal mailing list arguments over exactly which of the half-dozen smart pointer implementations they should be using.
  - p0nce 14y ago
    So, because C++ has imaginary problems, we should all switch to a language that solve them, while being worse at all other things that matters (you know, like code generation)?