From b0e927fed51bc519da7f745047be7a3fe8296219 Mon Sep 17 00:00:00 2001
From: root <root@ubuntu-14.04-amd64-vbox>
Date: Thu, 9 Jul 2015 23:23:03 +0000
Subject: [PATCH] Go Scheduler issue with sync.Mutex using gccgo

Signed-off-by: Srini Brahmaroutu <srbrahma@us.ibm.com>
---
 ioutils/readers.go         |  1 +
 ioutils/readers_test.go    |  2 +-
 ioutils/scheduler.go       |  6 ++++++
 ioutils/scheduler_gccgo.go | 13 +++++++++++++
 4 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100644 ioutils/scheduler.go
 create mode 100644 ioutils/scheduler_gccgo.go

diff --git a/ioutils/readers.go b/ioutils/readers.go
index 0e542cb..de15a00 100644
--- a/ioutils/readers.go
+++ b/ioutils/readers.go
@@ -189,6 +189,7 @@ func (r *bufReader) drain() {
 		reuseCount++
 		r.wait.Signal()
 		r.Unlock()
+		callSchedulerIfNecessary()
 		if err != nil {
 			break
 		}
diff --git a/ioutils/readers_test.go b/ioutils/readers_test.go
index d220487..0a39b6e 100644
--- a/ioutils/readers_test.go
+++ b/ioutils/readers_test.go
@@ -45,7 +45,7 @@ func TestReaderErrWrapperReadOnError(t *testing.T) {
 func TestReaderErrWrapperRead(t *testing.T) {
 	reader := strings.NewReader("a string reader.")
 	wrapper := NewReaderErrWrapper(reader, func() {
-		t.Fatalf("readErrWrapper should not have called the anonymous function on failure")
+		t.Fatalf("readErrWrapper should not have called the anonymous function")
 	})
 	// Read 20 byte (should be ok with the string above)
 	num, err := wrapper.Read(make([]byte, 20))
diff --git a/ioutils/scheduler.go b/ioutils/scheduler.go
new file mode 100644
index 0000000..3c88f29
--- /dev/null
+++ b/ioutils/scheduler.go
@@ -0,0 +1,6 @@
+// +build !gccgo
+
+package ioutils
+
+func callSchedulerIfNecessary() {
+}
diff --git a/ioutils/scheduler_gccgo.go b/ioutils/scheduler_gccgo.go
new file mode 100644
index 0000000..c11d02b
--- /dev/null
+++ b/ioutils/scheduler_gccgo.go
@@ -0,0 +1,13 @@
+// +build gccgo
+
+package ioutils
+
+import (
+	"runtime"
+)
+
+func callSchedulerIfNecessary() {
+	//allow or force Go scheduler to switch context, without explicitly
+	//forcing this will make it hang when using gccgo implementation
+	runtime.Gosched()
+}