Use atomic operations on flags field to make sure we aren't
losing a flag update during parallel map operations.
R=golang-dev, dave, r
CC=golang-dev
https://golang.org/cl/8377046
Doing grow work on reads is not multithreaded safe.
Changed code to do grow work only on inserts & deletes.
This is a short-term fix, eventually we'll want to do
grow work in parallel to recover the space of the old
table.
Fixes#5120.
R=bradfitz, khr
CC=golang-dev
https://golang.org/cl/8242043
Motivated by garbage profiling in HTTP benchmarks. This
changes means new empty maps are just one small allocation
(the HMap) instead the HMap + the relatively larger h->buckets
allocation. This helps maps which remain empty throughout
their life.
benchmark old ns/op new ns/op delta
BenchmarkNewEmptyMap 196 107 -45.41%
benchmark old allocs new allocs delta
BenchmarkNewEmptyMap 2 1 -50.00%
benchmark old bytes new bytes delta
BenchmarkNewEmptyMap 195 50 -74.36%
R=khr, golang-dev, r
CC=golang-dev
https://golang.org/cl/7722046
Hashtable is arranged as an array of
8-entry buckets with chained overflow.
Each bucket has 8 extra hash bits
per key to provide quick lookup within
a bucket. Table is grown incrementally.
Update #3885
Go time drops from 0.51s to 0.34s.
R=r, rsc, m3b, dave, bradfitz, khr, ugorji, remyoudompheng
CC=golang-dev
https://golang.org/cl/7504044
Dmitriy Vyukov
Albert Strasheim
Brad Fitzpatrick
Keith Randall