On Friday, 15 January 2021 at 07:35:00 UTC, H. S. Teoh wrote:
To be fair, the GC *has* improved over the years. Just not as quickly as people would like, but it *has* improved.
It cannot improve enough as a global collector without write barriers. No language has been able to do this. Therefore, D cannot do it.
Precise collection only helps when you have few pointers to trace.
improvement. But why would I? It takes 5x less effort to write GC code, and requires only a couple more days of effort to fix
That's like saying it takes 5x more time to write code in Swift than D. That is not at all reasonable.
Tracing GC is primarily useful when you have many small long-lived objects with unclear ownership and cyclic references that are difficult to break with weak pointers.
In those cases it is invaluable, but most well-designed programs have more tree-like structures and clear ownership.
after that to debug obscure pointer bugs. Life is too short to be squandered chasing down the 1000th double-free and the 20,000th dangling pointer in my life.
That has nothing to do with a tracing GC... Cyclic references is the only significant problem a tracing GC addresses compared to other solutions.
A lot of naysayers keep repeating GC performance issues as if it's a black-and-white, all-or-nothing question. It's not. You *can* write high-performance programs even with D's supposedly lousy GC -- just profile the darned thing, and
There are primarily two main problems, and they are not throughput, they are:
1. LATENCY: stopping the world will never be acceptable in interactive applications of some size, it is only acceptable in batch programs. In fact, even incremental collectors can cause a sluggish experience!
2. MEMORY CONSUMPTION: doing fewer collection cycles will increase the memory footprint. Ideally the collector would run all the time. In the cloud you pay for memory, so you want to keep memory consumption to a fixed level that you never exceed.
System level programming is primarily valuable for interactive applications, OS level programming, or embedded. So, no, it is not snobbish to not want a sluggish GC. Most other tasks are better done in high level languages.
