vmimpl: add a delay after an error from the tracked process

It usually means a kernel crash, in which case we want to give the
kernel some more time to print the whole coverage report to the console.

3 files changed, 8 insertions, 4 deletions

diff --git a/vm/vm.go b/vm/vm.go
index 6f66f8a37..879fc8feb 100644
--- a/vm/vm.go
+++ b/vm/vm.go
@@ -437,7 +437,7 @@ func (mon *monitor) createReport(defaultError string) *report.Report {
 }
 
 func (mon *monitor) waitForOutput() {
-	timer := time.NewTimer(waitForOutputTimeout * mon.inst.pool.timeouts.Scale)
+	timer := time.NewTimer(vmimpl.WaitForOutputTimeout * mon.inst.pool.timeouts.Scale)
 	defer timer.Stop()
 	for {
 		select {
@@ -470,6 +470,5 @@ var (
 	beforeContextDefault = 128 << 10
 	afterContext         = 128 << 10
 
-	tickerPeriod         = 10 * time.Second
-	waitForOutputTimeout = 10 * time.Second
+	tickerPeriod = 10 * time.Second
 )
diff --git a/vm/vm_test.go b/vm/vm_test.go
index afb8634bd..357f037d5 100644
--- a/vm/vm_test.go
+++ b/vm/vm_test.go
@@ -75,7 +75,7 @@ func (inst *testInstance) Close() {
 func init() {
 	beforeContextDefault = maxErrorLength + 100
 	tickerPeriod = 1 * time.Second
-	waitForOutputTimeout = 3 * time.Second
+	vmimpl.WaitForOutputTimeout = 3 * time.Second
 
 	ctor := func(env *vmimpl.Env) (vmimpl.Pool, error) {
 		return &testPool{}, nil
diff --git a/vm/vmimpl/vmimpl.go b/vm/vmimpl/vmimpl.go
index be7186889..00a815314 100644
--- a/vm/vmimpl/vmimpl.go
+++ b/vm/vmimpl/vmimpl.go
@@ -146,6 +146,8 @@ var (
 	Types = make(map[string]Type)
 )
 
+var WaitForOutputTimeout = 10 * time.Second
+
 func Multiplex(cmd *exec.Cmd, merger *OutputMerger, console io.Closer, timeout time.Duration,
 	stop, closed <-chan bool, debug bool) (<-chan []byte, <-chan error, error) {
 	errc := make(chan error, 1)
@@ -168,6 +170,9 @@ func Multiplex(cmd *exec.Cmd, merger *OutputMerger, console io.Closer, timeout t
 			signal(fmt.Errorf("instance closed"))
 		case err := <-merger.Err:
 			cmd.Process.Kill()
+			// Once the command has exited, we might want to let the full console
+			// output accumulate before we abort the console connection too.
+			time.Sleep(WaitForOutputTimeout)
 			if console != nil {
 				// Only wait for the merger if we're able to control the console stream.
 				console.Close()