test/e2e: use shared deadline for proxy readiness and fix doc comment

- Use a single deadline in waitForClientProxyReady so total wait across
  all proxies does not exceed the given timeout
- Fix WaitForOutput doc comment to accurately describe single pattern
  with count semantics

test/e2e/framework/process.go

@@ -9,6 +9,7 @@ import (
 	"strconv"
 	"time"
 
+	"github.com/fatedier/frp/pkg/config"
 	flog "github.com/fatedier/frp/pkg/util/log"
 	"github.com/fatedier/frp/test/e2e/framework/consts"
 	"github.com/fatedier/frp/test/e2e/pkg/process"
@@ -61,9 +62,22 @@ func (f *Framework) RunProcesses(serverTemplate string, clientTemplates []string
 		err = p.Start()
 		ExpectNoError(err)
 	}
-	// frpc needs time to connect and register proxies with frps.
-	if len(clientProcesses) > 0 {
-		time.Sleep(1500 * time.Millisecond)
+	// Wait for each client's proxies to register with frps.
+	// If any client has no proxies (e.g. visitor-only), fall back to sleep
+	// for the remaining time since visitors have no deterministic readiness signal.
+	allConfirmed := len(clientProcesses) > 0
+	start := time.Now()
+	for i, p := range clientProcesses {
+		configPath := f.clientConfPaths[len(f.clientConfPaths)-len(clientProcesses)+i]
+		if !waitForClientProxyReady(configPath, p, 5*time.Second) {
+			allConfirmed = false
+		}
+	}
+	if len(clientProcesses) > 0 && !allConfirmed {
+		remaining := 1500*time.Millisecond - time.Since(start)
+		if remaining > 0 {
+			time.Sleep(remaining)
+		}
 	}
 
 	return serverProcess, clientProcesses
@@ -105,6 +119,31 @@ func (f *Framework) GenerateConfigFile(content string) string {
 	return path
 }
 
+// waitForClientProxyReady parses the client config to extract proxy names,
+// then waits for each proxy's "start proxy success" log in the process output.
+// Returns true only if proxies were expected and all registered successfully.
+func waitForClientProxyReady(configPath string, p *process.Process, timeout time.Duration) bool {
+	_, proxyCfgs, _, _, err := config.LoadClientConfig(configPath, false)
+	if err != nil || len(proxyCfgs) == 0 {
+		return false
+	}
+
+	// Use a single deadline so the total wait across all proxies does not exceed timeout.
+	deadline := time.Now().Add(timeout)
+	for _, cfg := range proxyCfgs {
+		remaining := time.Until(deadline)
+		if remaining <= 0 {
+			return false
+		}
+		name := cfg.GetBaseConfig().Name
+		pattern := fmt.Sprintf("[%s] start proxy success", name)
+		if err := p.WaitForOutput(pattern, 1, remaining); err != nil {
+			return false
+		}
+	}
+	return true
+}
+
 // WaitForTCPReady polls a TCP address until a connection succeeds or timeout.
 func WaitForTCPReady(addr string, timeout time.Duration) error {
 	if timeout <= 0 {

test/e2e/pkg/process/process.go

@@ -4,15 +4,37 @@ import (
 	"bytes"
 	"context"
 	"errors"
+	"fmt"
 	"os/exec"
+	"strings"
 	"sync"
+	"time"
 )
 
+// SafeBuffer is a thread-safe wrapper around bytes.Buffer.
+// It is safe to call Write and String concurrently.
+type SafeBuffer struct {
+	mu  sync.Mutex
+	buf bytes.Buffer
+}
+
+func (b *SafeBuffer) Write(p []byte) (int, error) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	return b.buf.Write(p)
+}
+
+func (b *SafeBuffer) String() string {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	return b.buf.String()
+}
+
 type Process struct {
 	cmd         *exec.Cmd
 	cancel      context.CancelFunc
-	errorOutput *bytes.Buffer
-	stdOutput   *bytes.Buffer
+	errorOutput *SafeBuffer
+	stdOutput   *SafeBuffer
 
 	done     chan struct{}
 	closeOne sync.Once
@@ -36,8 +58,8 @@ func NewWithEnvs(path string, params []string, envs []string) *Process {
 		cancel: cancel,
 		done:   make(chan struct{}),
 	}
-	p.errorOutput = bytes.NewBufferString("")
-	p.stdOutput = bytes.NewBufferString("")
+	p.errorOutput = &SafeBuffer{}
+	p.stdOutput = &SafeBuffer{}
 	cmd.Stderr = p.errorOutput
 	cmd.Stdout = p.stdOutput
 	return p
@@ -101,3 +123,26 @@ func (p *Process) Output() string {
 func (p *Process) SetBeforeStopHandler(fn func()) {
 	p.beforeStopHandler = fn
 }
+
+// WaitForOutput polls the combined process output until the pattern is found
+// count time(s) or the timeout is reached. It also returns early if the process exits.
+func (p *Process) WaitForOutput(pattern string, count int, timeout time.Duration) error {
+	deadline := time.Now().Add(timeout)
+	for time.Now().Before(deadline) {
+		output := p.Output()
+		if strings.Count(output, pattern) >= count {
+			return nil
+		}
+		select {
+		case <-p.Done():
+			// Process exited, check one last time.
+			output = p.Output()
+			if strings.Count(output, pattern) >= count {
+				return nil
+			}
+			return fmt.Errorf("process exited before %d occurrence(s) of %q found", count, pattern)
+		case <-time.After(25 * time.Millisecond):
+		}
+	}
+	return fmt.Errorf("timeout waiting for %d occurrence(s) of %q", count, pattern)
+}