context: reduce memory usage of context tree
Modifies context package to use map[]struct{} rather than map[]bool,
since the map is intended as a set object. Also adds Benchmarks to
the context package switching between different types of root nodes
and a tree with different depths.
Included below are bytes deltas between the old and new code, using
these benchmarks.
benchmark old bytes new bytes delta
BenchmarkContextCancelTree/depth=1/Root=Background-8 176 176 +0.00%
BenchmarkContextCancelTree/depth=1/Root=OpenCanceler-8 560 544 -2.86%
BenchmarkContextCancelTree/depth=1/Root=ClosedCanceler-8 352 352 +0.00%
BenchmarkContextCancelTree/depth=10/Root=Background-8 3632 3488 -3.96%
BenchmarkContextCancelTree/depth=10/Root=OpenCanceler-8 4016 3856 -3.98%
BenchmarkContextCancelTree/depth=10/Root=ClosedCanceler-8 1936 1936 +0.00%
BenchmarkContextCancelTree/depth=100/Root=Background-8 38192 36608 -4.15%
BenchmarkContextCancelTree/depth=100/Root=OpenCanceler-8 38576 36976 -4.15%
BenchmarkContextCancelTree/depth=100/Root=ClosedCanceler-8 17776 17776 +0.00%
BenchmarkContextCancelTree/depth=1000/Root=Background-8 383792 367808 -4.16%
BenchmarkContextCancelTree/depth=1000/Root=OpenCanceler-8 384176 368176 -4.16%
BenchmarkContextCancelTree/depth=1000/Root=ClosedCanceler-8 176176 176176 +0.00%
Change-Id: I699ad704d9f7b461214e1651d24941927315b525
Reviewed-on: https://go-review.googlesource.com/25270
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/src/context/context.go b/src/context/context.go
index e40b63e..3afa3e9 100644
--- a/src/context/context.go
+++ b/src/context/context.go
@@ -252,9 +252,9 @@
child.cancel(false, p.err)
} else {
if p.children == nil {
- p.children = make(map[canceler]bool)
+ p.children = make(map[canceler]struct{})
}
- p.children[child] = true
+ p.children[child] = struct{}{}
}
p.mu.Unlock()
} else {
@@ -314,8 +314,8 @@
done chan struct{} // closed by the first cancel call.
mu sync.Mutex
- children map[canceler]bool // set to nil by the first cancel call
- err error // set to non-nil by the first cancel call
+ children map[canceler]struct{} // set to nil by the first cancel call
+ err error // set to non-nil by the first cancel call
}
func (c *cancelCtx) Done() <-chan struct{} {
