diff --git a/app/src/main/java/me/pqpo/log4a/LogInit.java b/app/src/main/java/me/pqpo/log4a/LogInit.java
index c2ad2ff..57a5dcd 100644
--- a/app/src/main/java/me/pqpo/log4a/LogInit.java
+++ b/app/src/main/java/me/pqpo/log4a/LogInit.java
@@ -10,6 +10,7 @@
 import me.pqpo.librarylog4a.Logger;
 import me.pqpo.librarylog4a.appender.AndroidAppender;
 import me.pqpo.librarylog4a.appender.FileAppender;
+import me.pqpo.librarylog4a.formatter.DateFileFormatter;
 import me.pqpo.librarylog4a.interceptor.Interceptor;
 
 /**
@@ -17,6 +18,8 @@
  */
 public class LogInit {
 
+    public static final int BUFFER_SIZE = 1024 * 400; //400k
+
     public static void init(Context context) {
         int level = Level.DEBUG;
         Interceptor wrapInterceptor = new Interceptor() {
@@ -38,9 +41,10 @@ public boolean intercept(LogData logData) {
                 .setLevel(level)
                 .addInterceptor(wrapInterceptor)
                 .setBufferFilePath(buffer_path)
-                .setBufferSize(4096);
+                .setFormatter(new DateFileFormatter())
+                .setBufferSize(BUFFER_SIZE);
         Logger logger = new Logger.Builder()
-//                .enableAndroidAppender(androidBuild)
+                .enableAndroidAppender(androidBuild)
                 .enableFileAppender(fileBuild)
                 .create();
         Log4a.setLogger(logger);
diff --git a/app/src/main/java/me/pqpo/log4a/MainActivity.java b/app/src/main/java/me/pqpo/log4a/MainActivity.java
index 0b83629..f459c74 100644
--- a/app/src/main/java/me/pqpo/log4a/MainActivity.java
+++ b/app/src/main/java/me/pqpo/log4a/MainActivity.java
@@ -9,9 +9,6 @@
 import android.widget.Toast;
 
 import java.io.File;
-import java.io.FileOutputStream;
-import java.io.IOException;
-import java.io.OutputStream;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Locale;
@@ -24,6 +21,8 @@
 import me.pqpo.librarylog4a.appender.Appender;
 import me.pqpo.librarylog4a.appender.FileAppender;
 
+import static me.pqpo.log4a.LogInit.BUFFER_SIZE;
+
 public class MainActivity extends AppCompatActivity {
 
     private static final String TAG = "MainActivity";
@@ -101,7 +100,6 @@ private void performanceTest(int times) {
 
         logger.addAppender(createLog4aFileAppender());
         doPerformanceTest("log4a" ,times);
-//        logger.flush();
         Log4a.release();
 
         Log4a.setLogger(logger);
@@ -110,7 +108,7 @@ private void performanceTest(int times) {
         Log4a.release();
 
         Log4a.setLogger(logger);
-        List<String> buffer = new ArrayList<>();
+        List<String> buffer = new ArrayList<>(times);
         logger.addAppender(createMemAppender(buffer));
         doPerformanceTest("array list log" ,times);
         buffer.clear();
@@ -126,28 +124,9 @@ private void performanceTest(int times) {
     }
 
     private Appender createFileAppender() {
-        File log = FileUtils.getLogDir(this);
-        File logFile = new File(log, "logFileTest.txt");
+        File logFile = new File(FileUtils.getLogDir(this), "logFileTest.txt");
         logFile.delete();
-        OutputStream os = null;
-        try {
-            logFile.createNewFile();
-            os = new FileOutputStream(logFile);
-        } catch (IOException e) {
-            e.printStackTrace();
-        }
-        final OutputStream oss = os;
-        return new AbsAppender() {
-            @Override
-            protected void doAppend(int logLevel, String tag, String msg) {
-                String logStr = String.format("%s/%s: %s\n", Level.getShortLevelName(logLevel), tag, msg);
-                try {
-                    oss.write(logStr.getBytes());
-                } catch (IOException e) {
-                    e.printStackTrace();
-                }
-            }
-        };
+        return new NoBufferFileAppender(logFile);
     }
 
     private Appender createMemAppender(final List<String> buffer) {
@@ -167,6 +146,7 @@ private Appender createLog4aFileAppender() {
         logFile.delete();
         FileAppender.Builder fileBuild = new FileAppender.Builder(this)
                 .setLogFilePath(logFile.getAbsolutePath())
+                .setBufferSize(BUFFER_SIZE)
                 .setBufferFilePath(cacheFile.getAbsolutePath());
         return fileBuild.create();
     }
diff --git a/app/src/main/java/me/pqpo/log4a/NoBufferFileAppender.java b/app/src/main/java/me/pqpo/log4a/NoBufferFileAppender.java
new file mode 100644
index 0000000..9b18095
--- /dev/null
+++ b/app/src/main/java/me/pqpo/log4a/NoBufferFileAppender.java
@@ -0,0 +1,62 @@
+package me.pqpo.log4a;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+
+import me.pqpo.librarylog4a.Level;
+import me.pqpo.librarylog4a.appender.AbsAppender;
+
+/**
+ * Created by pqpo on 2017/11/28.
+ */
+public class NoBufferFileAppender extends AbsAppender {
+
+    private File logFile;
+    private OutputStream outputStream;
+
+    public NoBufferFileAppender(File logFile) {
+        this.logFile = logFile;
+        openFileOutputStream();
+    }
+
+    private void openFileOutputStream() {
+        if (!logFile.exists()) {
+            try {
+                if(!logFile.createNewFile()) {
+                    return;
+                }
+                outputStream = new FileOutputStream(logFile);
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+
+    @Override
+    protected void doAppend(int logLevel, String tag, String msg) {
+        if (outputStream == null) {
+            return;
+        }
+        String logStr = String.format("%s/%s: %s\n", Level.getShortLevelName(logLevel), tag, msg);
+        try {
+            outputStream.write(logStr.getBytes());
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    @Override
+    public void release() {
+        super.release();
+        if (outputStream != null) {
+            try {
+                outputStream.flush();
+                outputStream.close();
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+}
diff --git a/librarylog4a/src/main/cpp/LogBuffer.cpp b/librarylog4a/src/main/cpp/LogBuffer.cpp
index 3951113..67b6788 100644
--- a/librarylog4a/src/main/cpp/LogBuffer.cpp
+++ b/librarylog4a/src/main/cpp/LogBuffer.cpp
@@ -7,6 +7,7 @@
 LogBuffer::LogBuffer(char *ptr, size_t capacity):
         buffer_ptr(ptr),
         buffer_capacity(capacity) {
+    offset = strlen(ptr);
 }
 
 LogBuffer::~LogBuffer() {
@@ -22,7 +23,7 @@ size_t LogBuffer::capacity() {
 }
 
 size_t LogBuffer::size() {
-    return strlen(ptr());
+    return offset;
 }
 
 char *LogBuffer::dataCopy() {
@@ -38,7 +39,8 @@ size_t LogBuffer::append(const char *log) {
     size_t len = strlen(log);
     size_t freeSize = emptySize();
     size_t writeSize = len <= freeSize ? len : freeSize;
-    memcpy(ptr() + size(), log, writeSize);
+    memcpy(ptr() + offset, log, writeSize);
+    offset += writeSize;
     return writeSize;
 }
 
@@ -55,6 +57,7 @@ void LogBuffer::async_flush(AsyncFileFlush *fileFlush) {
 void LogBuffer::clear() {
     std::lock_guard<std::recursive_mutex> lck_clear(log_mtx);
     memset(ptr(), '\0', capacity());
+    offset = 0;
 }
 
 void LogBuffer::release() {
diff --git a/librarylog4a/src/main/cpp/includes/LogBuffer.h b/librarylog4a/src/main/cpp/includes/LogBuffer.h
index 3218e14..a24b9e2 100644
--- a/librarylog4a/src/main/cpp/includes/LogBuffer.h
+++ b/librarylog4a/src/main/cpp/includes/LogBuffer.h
@@ -35,10 +35,9 @@ class LogBuffer {
     bool map_buffer = true;
 
 private:
+    size_t offset = 0;
     char* buffer_ptr = nullptr;
     size_t buffer_capacity = 0;
-    int log_file_fd = -1;
-    bool exit = false;
     std::recursive_mutex log_mtx;
 
 };