bug#68244: hash-table improvements

[Dmitry]

On Sun, Jan 7, 2024, at 7:26 AM, Stefan Monnier wrote:

Side note: I think reasoning won't get us out of this: either we decide

the choice is important, and then we try and do some

profiling/benchmarking

That's what I was going to suggest, but concluded that dropping the tallying increments in any of these constructors can lead to risky behavior in degenerate cases.

The use of memory allocation as a way to decide when to do the next GC

is just a crude tool anyway, which can often result in bad GC decisions,

anyway (e.g. typically during long periods of initialization where we

allocate many objects but don't generate almost any garbage).

Indeed, we have a latency/throughput tradeoff here with the current system, so it would be tempting to reduce the frequency of GCs at least in some cases.