Adding upstream version 1.18.10.upstream/1.18.10upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 54 insertions, 0 deletions

diff --git a/test/chan/select2.go b/test/chan/select2.go
new file mode 100644
index 0000000..31e27d7
--- /dev/null
+++ b/test/chan/select2.go
@@ -0,0 +1,54 @@
+// run
+
+// Copyright 2010 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.
+
+// Test that selects do not consume undue memory.
+
+package main
+
+import "runtime"
+
+func sender(c chan int, n int) {
+	for i := 0; i < n; i++ {
+		c <- 1
+	}
+}
+
+func receiver(c, dummy chan int, n int) {
+	for i := 0; i < n; i++ {
+		select {
+		case <-c:
+			// nothing
+		case <-dummy:
+			panic("dummy")
+		}
+	}
+}
+
+func main() {
+	runtime.MemProfileRate = 0
+
+	c := make(chan int)
+	dummy := make(chan int)
+
+	// warm up
+	go sender(c, 100000)
+	receiver(c, dummy, 100000)
+	runtime.GC()
+	memstats := new(runtime.MemStats)
+	runtime.ReadMemStats(memstats)
+	alloc := memstats.Alloc
+
+	// second time shouldn't increase footprint by much
+	go sender(c, 100000)
+	receiver(c, dummy, 100000)
+	runtime.GC()
+	runtime.ReadMemStats(memstats)
+
+	// Be careful to avoid wraparound.
+	if memstats.Alloc > alloc && memstats.Alloc-alloc > 1.1e5 {
+		println("BUG: too much memory for 100,000 selects:", memstats.Alloc-alloc)
+	}
+}