alt Hacker News> TigerStyle: All memory must be statically allocated at startup. No memory may be dynamically allocated (or freed and reallocated) after initialization. This avoids unpredictable behavior that can significantly affect performance, and avoids use-after-free.
Maybe maintaining an array of NULL-orders satisfies the letter of the "no dynamic allocation" law, but I'm not convinced it satisfies the spirit.
Haven't you just written a buffer of NULL-orders, which you proceed to loan out to callers (i.e. "allocate" and "reallocate"?).
Someone else's battle-hardened allocator might be slow or buggy, so you write your own as part of the business logic implementation?
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The second half of the article talks about avoiding this, by not keeping any separate index of the (un)allocated orders. All the orders are allocated, and all are processed by the same pipeline, it's just that some of them are nearly no-ops. Each order contains its own no-op/some-op state marker, so it's hardened by being self-describing, with no other data structure that can disagree.
Seems wasteful to spin through lots of no-op orders? Yes it is, but if it runs at all, you've (i) proved you can iterate through the whole array, so fewer surprises when the active order count grows; and (ii) given the cache an easy life by maximizing locality.
>Someone else's battle-hardened allocator might be slow or buggy, so you write your own as part of the business logic implementation?
In infrastructure where speed and reliability are highly valued? Absolutely. The gains obtained from proper memory layout and specialized use are massive. As long as you have the reason to do it, it's an easy win. I believe that the Zig standard library has different specialized allocators, so you don't even have to write your own buggy implementation.
It’s (mostly) not about performance, it’s about minimizing failure. Static memory allocation makes you OOM-proof.
TigerStyle is strictly concerned about dynamic allocation from the perspective of the OS.
Once you have that pool of "objects" that can be recycled throughout the lifetime of the program, you have a guarantee that actual allocation can only be interpreted in a specific way, i.e. all objects have the same size, alignment, etc so you don't have nearly the same level of concern or detail of implementation as an actual allocator in the common understanding of the word. A simple free-list gets you pretty far.