| commit | dabd9d9837539dfb3a7647ace074a3e2df14cc3b | |
| author | Herbert Valerio Riedel <hvr@gnu.org> | |
| Tue, 27 Sep 2016 08:03:06 +0000 (27 10:03 +0200) | ||
| committer | GitHub <noreply@github.com> | |
| Tue, 27 Sep 2016 08:03:06 +0000 (27 10:03 +0200) | ||
| tree | dca800d4e613c1fab7a6805ede1685581e8856aa | treesnapshot (tar.gz zip) |
| parent | 2ccfce176d4b6dc88daed7b8ccd75de0f4337336 | commitdiff |
Make `PackageName` type opaque (#3896)
When looking at heap-profiles of `cabal-install`, the `(:)` constructor
stands out as the most-allocated constructor on the heap.
Having to handle 10k+ package names contributes to the allocation
numbers, especially on 64bit archs where ASCII `String`s have a 24 byte
per character footprint.
This commit is a preparatory commit to pave the way for changing
`PackageName`'s internal representation to something like
`ShortByteString` (which is essentially a thin wrapper around primitive
`ByteArray#`s which themselves have have an overhead of 2 words + one
byte per ASCII character rounded up to nearest word) which would allow
to reduce the memory footprint by a full order of magnitude, as well as
reduce pointer chasing and GC overhead.
When looking at heap-profiles of `cabal-install`, the `(:)` constructor
stands out as the most-allocated constructor on the heap.
Having to handle 10k+ package names contributes to the allocation
numbers, especially on 64bit archs where ASCII `String`s have a 24 byte
per character footprint.
This commit is a preparatory commit to pave the way for changing
`PackageName`'s internal representation to something like
`ShortByteString` (which is essentially a thin wrapper around primitive
`ByteArray#`s which themselves have have an overhead of 2 words + one
byte per ASCII character rounded up to nearest word) which would allow
to reduce the memory footprint by a full order of magnitude, as well as
reduce pointer chasing and GC overhead.
39 files changed: