bhurt

I think this talk is relevant: https://ocaml.janestreet.com/?q=node/61

Probably ease of implementation. You can just grab the Boehm conservative GC, slap it in, and bang- you've got GC. You can even add GC this way to C/C++ programs.

Unfortunately, Boehm has draw backs- because it's getting no help from the compiler, it can't tell integers from pointers. So it has to treat everything that looks like it might be a pointer as a pointer, even if it's an integer (or floating point number). Which means that it's possible for garbage to not be collected, because there is an integer that happens to have the same value as the address of the garbage object. And, of course, once you can't collect that object, you can't collect all the objects it refers to (including false pointers), and so on.

The odds of this happening are a function of what percentage of the virtual address space is in use- once some critical threshold is reached, the amount of garbage that can't be collected due to false pointers just explodes. On 32-bit platforms, I've seen this happen with heap sizes of only a few hundred megabytes. And the advice to work around this is exactly what the responder said- use less memory, don't use large ints (which are more likely to be mistaken for pointers), etc. Also, the problem goes away (for the time being) on 64 bits, because the percentage of memory used drops. A terabyte of memory on a 64-bit system is the same fraction of the total address space as a kilobyte of memory is on a 32-bit system.

The C standards committee has been broken since C99 introduced long long, thus silently breaking conforming code.

How do you print out a size_t, portably, without losing information? The standard says size_t is an unsigned integer type, but doesn't say way size. However, the C89 spec explicitly stated that there are no integers sizes longer than long- so the conforming way to do this is to explicitly cast the size_t to unsigned long (which, while it may add bits, is guaranteed not to lose them), and print the unsigned long.

In an attempt to save all the broken, non-conforming code that assumed that sizeof(int) == sizeof(long), C99 introduced the long long type. And, among other things, allowed size_t to now be unsigned long long. Which meant the conforming C89 code that wants to print out a size_t is now wrong. Worse yet, it's silently broken- because the type cast is explicit, the compiler has to assume it's correct. They added a new way to print size_t's, granted- but this is no help for the legacy code (or code that needs to continue to support C89-only compilers).

Of course, the punchline here is that I have yet to see code that assumed sizeof(int) == sizeof(long) that didn't also assume sizeof(void *) == sizeof(int). So all that broken non-conforming code they were trying to save? It still needed to get fixed for 64-bit.

I wished I lived in the authors world. A world where you don't have to maintain the code you wrote- or worse yet, someone else wrote. Where you could declare a program "done" and walk away and never have to revisit it. A world where "mostly works" is good enough- secure in the knowledge that you're not going to be rousted out bed at 2 in the morning on a weekend because some server in outer Mongolia hit that corner case you never thought to test. A world where all programs are small enough to fit into my head, completely, in all details. So I could simply know, if I change this, that will break.

That is not, unfortunately, the world I live in. If it is the world you live in, more power to you. Count your blessing and live happily. But the rest of us need all the help we can get.

One reason I know we're not in a bubble: because everyone is saying we're in a bubble.

For you young whippersnappers who were too young to remember the 90's, a bubble is a manifestation of irrational exuberance- with (almost) everyone saying it's a whole new market, it doesn't matter how much the thing costs it's worth it to buy it because it's price is just going to keep going up up up, so do whatever you need to do to buy in now, because the longer you wait, the less you make.

In other words- it's a bubble when everyone is saying it's not a bubble. But if everyone is saying it IS a bubble, then it's not a bubble.

There is a difference between a healthy (or at least "not on death's doorstop") economy and a bubble.