Static Memory JavaScript with Object Pools (2013)

Object pooling is generally considered to be the worse approach, because it's tricky to know when to put object back in the pool. Realistically this mean ref counting. The code will get more complicated and bugs will happen when an object is returned to the pool but is still used. Each object will get bigger, since now it has to have an extra word associated with it.

Also, this puts undue stress on the GC. Collections won't pick up pooled objects, even when they could have been. This causes memory pressure because the program may actually need to allocate a large amount of memory, but none could be freed up.

I think the real answer here is to just do less work. Don't try to change a program to let it keep using lots of memory. Instead, make it so it needs hardly any memory in the first place.

There's 2 main challenges to a pool based approach

1) Knowing up front how much memory you'll need 2) Complex DOM object pooling

In practice 1 gets solved by growing your pool, this also solves the problem with startup delays due to pre-allocation, but you need some way of knowing when to stop growing the pool and potentially evicting/re-using pool members. You can easily find yourself simply having written a much worse garbage collector of your own.

#2 is the realm of things like React-Virtualize. You need to be cognizant of acquiring handles to browser resources, and how to manage those life-cycles. You can end up in a case where your pool is 95% properly managed, but the leaky 5% still makes costly GC pauses.

In C++, there are kinds of programs where "#define free(x)" results in the same effect, including the large speedup.

But this is an important trick that also works in Java, C++ and Go.

It can be combined further. For instance, where you're keeping track of many small pieces of a big chunk of data, having the big chunk somewhere with a big primitive type array containing the actual data and then having Flywheel pattern accesses to it can result in incredible speeds.