diff --git a/task/handler/runner.go b/task/handler/runner.go
index cc58bad..c0c8609 100644
--- a/task/handler/runner.go
+++ b/task/handler/runner.go
@@ -4,7 +4,6 @@ import (
 	"bufio"
 	"context"
 	"encoding/json"
-	"fmt"
 	"github.com/apex/log"
 	"github.com/cenkalti/backoff/v4"
 	"github.com/crawlab-team/crawlab-core/constants"
@@ -17,7 +16,6 @@ import (
 	"github.com/crawlab-team/crawlab-core/models/models"
 	"github.com/crawlab-team/crawlab-core/sys_exec"
 	"github.com/crawlab-team/crawlab-core/task/fs"
-	"github.com/crawlab-team/crawlab-core/utils"
 	"github.com/crawlab-team/crawlab-db/mongo"
 	grpc "github.com/crawlab-team/crawlab-grpc"
 	"github.com/crawlab-team/go-trace"
@@ -28,6 +26,7 @@ import (
 	"go.uber.org/dig"
 	"os"
 	"os/exec"
+	"strings"
 	"time"
 )
 
@@ -38,6 +37,7 @@ type Runner struct {
 
 	// settings
 	subscribeTimeout time.Duration
+	bufferSize       int
 
 	// internals
 	cmd  *exec.Cmd                        // process command instance
@@ -53,8 +53,8 @@ type Runner struct {
 	sub  grpc.TaskService_SubscribeClient // grpc task service stream client
 
 	// log internals
-	scannerStdout *bufio.Scanner
-	scannerStderr *bufio.Scanner
+	scannerStdout *bufio.Reader
+	scannerStderr *bufio.Reader
 	logBatchSize  int
 }
 
@@ -251,11 +251,11 @@ func (r *Runner) configureCmd() {
 func (r *Runner) configureLogging() {
 	// set stdout reader
 	stdout, _ := r.cmd.StdoutPipe()
-	r.scannerStdout = bufio.NewScanner(stdout)
+	r.scannerStdout = bufio.NewReaderSize(stdout, r.bufferSize)
 
 	// set stderr reader
 	stderr, _ := r.cmd.StderrPipe()
-	r.scannerStderr = bufio.NewScanner(stderr)
+	r.scannerStderr = bufio.NewReaderSize(stderr, r.bufferSize)
 }
 
 func (r *Runner) startLogging() {
@@ -267,44 +267,25 @@ func (r *Runner) startLogging() {
 }
 
 func (r *Runner) startLoggingReaderStdout() {
-	utils.LogDebug("begin startLoggingReaderStdout")
-	var lines []string
-	for r.scannerStdout.Scan() {
-		line := r.scannerStdout.Text()
-		lines = append(lines, line)
-		if len(lines) >= r.logBatchSize {
-			r.writeLogLines(lines)
-			utils.LogDebug(fmt.Sprintf("scannerStdout lines: %s", lines))
-			lines = []string{}
+	for {
+		line, err := r.scannerStdout.ReadString(byte('\n'))
+		if err != nil {
+			break
 		}
+		line = strings.TrimSuffix(line, "\n")
+		r.writeLogLines([]string{line})
 	}
-	if len(lines) > 0 {
-		r.writeLogLines(lines)
-		utils.LogDebug(fmt.Sprintf("scannerStdout lines: %s", lines))
-
-	}
-	// reach end
-	utils.LogDebug("scannerStdout reached end")
 }
 
 func (r *Runner) startLoggingReaderStderr() {
-	utils.LogDebug("begin startLoggingReaderStderr")
-	var lines []string
-	for r.scannerStderr.Scan() {
-		line := r.scannerStderr.Text()
-		lines = append(lines, line)
-		if len(lines) >= r.logBatchSize {
-			r.writeLogLines(lines)
-			utils.LogDebug(fmt.Sprintf("scannerStderr lines: %s", lines))
-			lines = []string{}
+	for {
+		line, err := r.scannerStderr.ReadString(byte('\n'))
+		if err != nil {
+			break
 		}
+		line = strings.TrimSuffix(line, "\n")
+		r.writeLogLines([]string{line})
 	}
-	if len(lines) > 0 {
-		r.writeLogLines(lines)
-		utils.LogDebug(fmt.Sprintf("scannerStderr lines: %s", lines))
-	}
-	// reach end
-	utils.LogDebug("scannerStderr reached end")
 }
 
 func (r *Runner) startHealthCheck() {
@@ -603,6 +584,7 @@ func NewTaskRunner(id primitive.ObjectID, svc interfaces.TaskHandlerService, opt
 	// runner
 	r := &Runner{
 		subscribeTimeout: 30 * time.Second,
+		bufferSize:       1024 * 1024,
 		svc:              svc,
 		tid:              id,
 		ch:               make(chan constants.TaskSignal),
diff --git a/task/log/file_driver.go b/task/log/file_driver.go
index 0024738..f127c79 100644
--- a/task/log/file_driver.go
+++ b/task/log/file_driver.go
@@ -88,10 +88,16 @@ func (d *FileLogDriver) Find(id string, pattern string, skip int, limit int) (li
 	}
 	defer f.Close()
 
-	sc := bufio.NewScanner(f)
+	sc := bufio.NewReaderSize(f, 1024*1024*10)
 
 	i := -1
-	for sc.Scan() {
+	for {
+		line, err := sc.ReadString(byte('\n'))
+		if err != nil {
+			break
+		}
+		line = strings.TrimSuffix(line, "\n")
+
 		i++
 
 		if i < skip {
@@ -102,12 +108,8 @@ func (d *FileLogDriver) Find(id string, pattern string, skip int, limit int) (li
 			break
 		}
 
-		line := sc.Text()
 		lines = append(lines, line)
 	}
-	if err := sc.Err(); err != nil {
-		return nil, trace.TraceError(err)
-	}
 
 	return lines, nil
 }