Hacker News Reader

Comment by trzeci | Hacker News Reader

This is very good news for Emscripten / WebAssembly developers. One of the main limitation in ASM.js / WASM based applications is a size of emulated HEAP. It has to be a contiguous memory block, what is so unlikely to allocate by browser (from my tests it's ~10% of users cannot allocate 256MB for HEAP). It's that due a memory fragmentation.

Having 64 bit by default fixes such problem. That's a good move. Well done moz://a

View on HN

It dosen't fix the problem unfortunately, the JIT code in firefox is effectively 32bit, it can only operate on a 32bit contigious range.

It does fix the memory fragmentation problem, in that it's almost guaranteed you'll have a contiguous range you can allocate (assuming you have enough memory in the first place). In practice this has been a serious issue.

There is a separate issue of programs that need more than a 32-bit allocation for their memory. Not many apps hit that limit so far, and it's tricky to support anyhow since you need 64-bit ints for pointers and JS doesn't support that well. wasm64 will address this eventually.

It's easier to get a contiguous chunk of memory if you're able to wrangle it in the 64-bit space, then slice out a 4GB chunk for 32-bit code.

Why do you capitalise heap?

`HEAP` is the name of a large typed array variable that represents the original program's heap.

Must be a PERL programmer.

Why type moz://a ?

If you type mozilla in Zilla Slab Highlight Bold[0], it ligatures to moz://a, suggesting that mozilla is the correct spelling, and moz://a is a logotype.

[0]: https://fonts.google.com/specimen/Zilla+Slab+Highlight

Apparently, it's their new logo: https://www.wired.com/2017/01/introducing-mozillas-new-logo-...

Reply on news.ycombinator.com