fix(perf-harness): drain terminal output on shutdown

commit: 1d11e86430e010f0a07490b461a173c0f7795e6d
author: brice · 3mo ago · 2026-07-18 15:33 UTC
parent: 19fd124
signature: GPG VerifiedCD88F9E564E0102646FB6077A1A07C7C7C3E349D · arch-gpg Verified for the committer email

2 files · +67 -0

M cmd/vev-perf-harness/launcher.go +17 -0


@@ -628,6 +628,23 @@ func (e *ptyLocalEcho) applicationOutput(chunk []byte) []byte {
628	628		func (p *cliProcess) Close() error {
629	629		var result error
630	630		p.closed.Do(func() {
	631	+	// No measurement waits for terminal chunks during teardown. Continue
	632	+	// consuming them so a full channel cannot block the client before it
	633	+	// receives the shell exit request and closes its transport receive span.
	634	+	if p.chunks != nil && p.done != nil {
	635	+	go func() {
	636	+	for {
	637	+	select {
	638	+	case _, ok := <-p.chunks:
	639	+	if !ok {
	640	+	return
	641	+	}
	642	+	case <-p.done:
	643	+	return
	644	+	}
	645	+	}
	646	+	}()
	647	+	}
631	648		// A public terminal client owns a shell session. Ask that shell to exit
632	649		// before closing the PTY so its transport can finish its receive span;
633	650		// this avoids turning ordinary harness teardown into an aborted trace.


@@ -628,6 +628,23 @@ func (e *ptyLocalEcho) applicationOutput(chunk []byte) []byte {
628	func (p *cliProcess) Close() error {	628		func (p *cliProcess) Close() error {
629	var result error	629		var result error
630	p.closed.Do(func() {	630		p.closed.Do(func() {
		631	+	// No measurement waits for terminal chunks during teardown. Continue
		632	+	// consuming them so a full channel cannot block the client before it
		633	+	// receives the shell exit request and closes its transport receive span.
		634	+	if p.chunks != nil && p.done != nil {
		635	+	go func() {
		636	+	for {
		637	+	select {
		638	+	case _, ok := <-p.chunks:
		639	+	if !ok {
		640	+	return
		641	+	}
		642	+	case <-p.done:
		643	+	return
		644	+	}
		645	+	}
		646	+	}()
		647	+	}
631	// A public terminal client owns a shell session. Ask that shell to exit	648		// A public terminal client owns a shell session. Ask that shell to exit
632	// before closing the PTY so its transport can finish its receive span;	649		// before closing the PTY so its transport can finish its receive span;
633	// this avoids turning ordinary harness teardown into an aborted trace.	650		// this avoids turning ordinary harness teardown into an aborted trace.

M cmd/vev-perf-harness/launcher_test.go +50 -0


@@ -18,6 +18,56 @@ import (
18	18		"github.com/bnema/vev/pkg/safedir"
19	19		)
20	20
	21	+	type discardTerminalOutput struct{}
	22	+
	23	+	func (discardTerminalOutput) Write(p []byte) (int, error) { return len(p), nil }
	24	+	func (discardTerminalOutput) Sync() error { return nil }
	25	+	func (discardTerminalOutput) Close() error { return nil }
	26	+
	27	+	func TestCLIProcessCloseDrainsQueuedTerminalOutputBeforeClientExit(t *testing.T) {
	28	+	harnessPTY, clientPTY := net.Pipe()
	29	+	t.Cleanup(func() { _ = clientPTY.Close() })
	30	+	waitErr := make(chan error)
	31	+	secondRead := make(chan struct{})
	32	+	p := &cliProcess{
	33	+	pty: harnessPTY,
	34	+	output: discardTerminalOutput{},
	35	+	chunks: make(chan []byte, 1),
	36	+	done: make(chan struct{}),
	37	+	waitErr: waitErr,
	38	+	waitTimeout: func() <-chan time.Time { return time.After(time.Second) },
	39	+	}
	40	+	go p.copyTerminal()
	41	+	go func() {
	42	+	_, _ = clientPTY.Write([]byte("first"))
	43	+	_, _ = clientPTY.Write([]byte("second"))
	44	+	close(secondRead)
	45	+	buf := make([]byte, len("exit\n"))
	46	+	if _, err := clientPTY.Read(buf); err != nil {
	47	+	return
	48	+	}
	49	+	if _, err := clientPTY.Write([]byte("third")); err != nil {
	50	+	return
	51	+	}
	52	+	waitErr <- nil
	53	+	}()
	54	+	select {
	55	+	case <-secondRead:
	56	+	case <-time.After(time.Second):
	57	+	t.Fatal("terminal reader did not queue output")
	58	+	}
	59	+	closed := make(chan error, 1)
	60	+	go func() { closed <- p.Close() }()
	61	+	select {
	62	+	case err := <-closed:
	63	+	if err != nil {
	64	+	t.Fatal(err)
	65	+	}
	66	+	case <-time.After(time.Second):
	67	+	t.Fatal("Close did not drain queued terminal output before waiting for client exit")
	68	+	}
	69	+	}
	70	+
21	71		func TestCLIProcessCloseKeepsTerminalDrainActiveUntilClientExit(t *testing.T) {
22	72		pty, err := os.CreateTemp(t.TempDir(), "pty")
23	73		if err != nil {


@@ -18,6 +18,56 @@ import (
18	"github.com/bnema/vev/pkg/safedir"	18		"github.com/bnema/vev/pkg/safedir"
19	)	19		)
20		20
		21	+	type discardTerminalOutput struct{}
		22	+
		23	+	func (discardTerminalOutput) Write(p []byte) (int, error) { return len(p), nil }
		24	+	func (discardTerminalOutput) Sync() error { return nil }
		25	+	func (discardTerminalOutput) Close() error { return nil }
		26	+
		27	+	func TestCLIProcessCloseDrainsQueuedTerminalOutputBeforeClientExit(t *testing.T) {
		28	+	harnessPTY, clientPTY := net.Pipe()
		29	+	t.Cleanup(func() { _ = clientPTY.Close() })
		30	+	waitErr := make(chan error)
		31	+	secondRead := make(chan struct{})
		32	+	p := &cliProcess{
		33	+	pty: harnessPTY,
		34	+	output: discardTerminalOutput{},
		35	+	chunks: make(chan []byte, 1),
		36	+	done: make(chan struct{}),
		37	+	waitErr: waitErr,
		38	+	waitTimeout: func() <-chan time.Time { return time.After(time.Second) },
		39	+	}
		40	+	go p.copyTerminal()
		41	+	go func() {
		42	+	_, _ = clientPTY.Write([]byte("first"))
		43	+	_, _ = clientPTY.Write([]byte("second"))
		44	+	close(secondRead)
		45	+	buf := make([]byte, len("exit\n"))
		46	+	if _, err := clientPTY.Read(buf); err != nil {
		47	+	return
		48	+	}
		49	+	if _, err := clientPTY.Write([]byte("third")); err != nil {
		50	+	return
		51	+	}
		52	+	waitErr <- nil
		53	+	}()
		54	+	select {
		55	+	case <-secondRead:
		56	+	case <-time.After(time.Second):
		57	+	t.Fatal("terminal reader did not queue output")
		58	+	}
		59	+	closed := make(chan error, 1)
		60	+	go func() { closed <- p.Close() }()
		61	+	select {
		62	+	case err := <-closed:
		63	+	if err != nil {
		64	+	t.Fatal(err)
		65	+	}
		66	+	case <-time.After(time.Second):
		67	+	t.Fatal("Close did not drain queued terminal output before waiting for client exit")
		68	+	}
		69	+	}
		70	+
21	func TestCLIProcessCloseKeepsTerminalDrainActiveUntilClientExit(t *testing.T) {	71		func TestCLIProcessCloseKeepsTerminalDrainActiveUntilClientExit(t *testing.T) {
22	pty, err := os.CreateTemp(t.TempDir(), "pty")	72		pty, err := os.CreateTemp(t.TempDir(), "pty")
23	if err != nil {	73		if err != nil {