diff options
author | Russ Cox <rsc@golang.org> | 2011-04-13 23:42:06 -0400 |
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committer | Russ Cox <rsc@golang.org> | 2011-04-13 23:42:06 -0400 |
commit | 507df959e48835cc58f89cdf23fcbead54d03563 (patch) | |
tree | 37cff4db1baffad01f392f5d5c3c8a6294fd112f /test/gc2.go | |
parent | 4c006182dcb2c7fef7d05c121a5e9b3c0291cf82 (diff) | |
download | go-507df959e48835cc58f89cdf23fcbead54d03563.tar.gz go-507df959e48835cc58f89cdf23fcbead54d03563.zip |
runtime: drop chan circular linked list in favor of circular buffer
The list elements are already being allocated out of a
single memory buffer. We can drop the Link* pointer
following and the memory it requires, replacing it with
index operations.
The change also keeps a channel from containing a pointer
back into its own allocation block, which would create a
cycle. Blocks involved in cycles are not guaranteed to be
finalized properly, and channels depend on finalizers to
free OS-level locks on some systems. The self-reference
was keeping channels from being garbage collected.
runtime-gdb.py will need to be updated in order to dump
the content of buffered channels with the new data structure.
Fixes #1676.
R=ken2, r
CC=golang-dev
https://golang.org/cl/4411045
Diffstat (limited to 'test/gc2.go')
-rw-r--r-- | test/gc2.go | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/test/gc2.go b/test/gc2.go new file mode 100644 index 0000000000..c5c6cbe4bb --- /dev/null +++ b/test/gc2.go @@ -0,0 +1,41 @@ +// $G $D/$F.go && $L $F.$A && ./$A.out + +// Copyright 2011 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// Check that buffered channels are garbage collected properly. +// An interesting case because they have finalizers and used to +// have self loops that kept them from being collected. +// (Cyclic data with finalizers is never finalized, nor collected.) + +package main + +import ( + "fmt" + "os" + "runtime" +) + +func main() { + const N = 10000 + st := runtime.MemStats + for i := 0; i < N; i++ { + c := make(chan int, 10) + _ = c + if i%100 == 0 { + for j := 0; j < 4; j++ { + runtime.GC() + runtime.Gosched() + runtime.GC() + runtime.Gosched() + } + } + } + + obj := runtime.MemStats.HeapObjects - st.HeapObjects + if obj > N/5 { + fmt.Println("too many objects left:", obj) + os.Exit(1) + } +} |