diff --git a/.gitignore b/.gitignore
index 7419d78..532ecfe 100644
--- a/.gitignore
+++ b/.gitignore
@@ -11,6 +11,7 @@
 .idea/modules
 .idea/markdown-navigator.xml
 .idea/modules.xml
+.idea/**
 
 # Gradle:
 .idea/**/gradle.xml
diff --git a/.idea/runConfigurations.xml b/.idea/runConfigurations.xml
deleted file mode 100644
index 7f68460..0000000
--- a/.idea/runConfigurations.xml
+++ /dev/null
@@ -1,12 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="RunConfigurationProducerService">
-    <option name="ignoredProducers">
-      <set>
-        <option value="org.jetbrains.plugins.gradle.execution.test.runner.AllInPackageGradleConfigurationProducer" />
-        <option value="org.jetbrains.plugins.gradle.execution.test.runner.TestClassGradleConfigurationProducer" />
-        <option value="org.jetbrains.plugins.gradle.execution.test.runner.TestMethodGradleConfigurationProducer" />
-      </set>
-    </option>
-  </component>
-</project>
\ No newline at end of file
diff --git a/.idea/vcs.xml b/.idea/vcs.xml
deleted file mode 100644
index 94a25f7..0000000
--- a/.idea/vcs.xml
+++ /dev/null
@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="VcsDirectoryMappings">
-    <mapping directory="$PROJECT_DIR$" vcs="Git" />
-  </component>
-</project>
\ No newline at end of file
diff --git a/app/src/main/java/devliving/online/securedpreferencestoresample/MainActivity.java b/app/src/main/java/devliving/online/securedpreferencestoresample/MainActivity.java
index 2d75123..f665813 100644
--- a/app/src/main/java/devliving/online/securedpreferencestoresample/MainActivity.java
+++ b/app/src/main/java/devliving/online/securedpreferencestoresample/MainActivity.java
@@ -3,6 +3,8 @@
 import android.content.Intent;
 import android.content.SharedPreferences;
 import android.os.Bundle;
+import android.os.Handler;
+import android.os.Looper;
 import android.support.v7.app.AppCompatActivity;
 import android.util.Log;
 import android.view.View;
@@ -20,7 +22,7 @@ public class MainActivity extends AppCompatActivity {
 
     EditText text1, number1, date1, text2, number2;
 
-    Button reloadButton, saveButton, imageDemoBtn;
+    Button reloadButton, saveButton, multiThreadingButton, imageDemoBtn;
 
     String TEXT_1 = "text_short", TEXT_2 = "text_long", NUMBER_1 = "number_int", NUMBER_2 = "number_float", DATE_1 = "date_text", DATE_2 = "date_long";
 
@@ -38,6 +40,7 @@ protected void onCreate(Bundle savedInstanceState) {
 
         reloadButton = (Button) findViewById(R.id.reload);
         saveButton = (Button) findViewById(R.id.save);
+        multiThreadingButton = (Button) findViewById(R.id.multi_threading);
         imageDemoBtn = findViewById(R.id.tryFile);
 
         try {
@@ -79,6 +82,49 @@ public void onClick(View view) {
                 }
             }
         });
+        multiThreadingButton.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                Runnable saveJob = new Runnable() {
+                    @Override
+                    public void run() {
+                        Log.d("queen", Thread.currentThread().getName() + " gets started");
+                        while(true) {
+                            saveData();
+                            reloadData();
+                        }
+                    }
+                };
+
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+                new Thread(saveJob).start();
+            }
+        });
+
 
         imageDemoBtn.setOnClickListener(v -> {
             Intent intent = new Intent(this, FileDemoActivity.class);
@@ -106,17 +152,22 @@ protected boolean recover(Exception e, KeyStore keyStore, List<String> keyAliase
     void reloadData()  {
         SecuredPreferenceStore prefStore = SecuredPreferenceStore.getSharedInstance();
 
-        String textShort = prefStore.getString(TEXT_1, null);
-        String textLong = prefStore.getString(TEXT_2, null);
-        int numberInt = prefStore.getInt(NUMBER_1, 0);
-        float numberFloat = prefStore.getFloat(NUMBER_2, 0);
-        String dateText = prefStore.getString(DATE_1, null);
-
-        text1.setText(textShort);
-        text2.setText(textLong);
-        number1.setText(String.valueOf(numberInt));
-        number2.setText(String.valueOf(numberFloat));
-        date1.setText(dateText);
+        final String textShort = prefStore.getString(TEXT_1, null);
+        final String textLong = prefStore.getString(TEXT_2, null);
+        final int numberInt = prefStore.getInt(NUMBER_1, 0);
+        final float numberFloat = prefStore.getFloat(NUMBER_2, 0);
+        final String dateText = prefStore.getString(DATE_1, null);
+
+        new Handler(Looper.getMainLooper()).post(new Runnable() {
+            @Override
+            public void run() {
+                text1.setText(textShort);
+                text2.setText(textLong);
+                number1.setText(String.valueOf(numberInt));
+                number2.setText(String.valueOf(numberFloat));
+                date1.setText(dateText);
+            }
+        });
     }
 
     void saveData() {
diff --git a/app/src/main/res/layout/activity_main.xml b/app/src/main/res/layout/activity_main.xml
index bb68a7f..9ebc0b4 100644
--- a/app/src/main/res/layout/activity_main.xml
+++ b/app/src/main/res/layout/activity_main.xml
@@ -76,6 +76,12 @@
                 android:layout_height="wrap_content"
                 android:layout_weight="1"
                 android:text="Save" />
+            <Button
+                android:id="@+id/multi_threading"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:text="multi-threading" />
         </LinearLayout>
 
         <Button
diff --git a/securedpreferencestore/src/main/java/devliving/online/securedpreferencestore/EncryptionManager.java b/securedpreferencestore/src/main/java/devliving/online/securedpreferencestore/EncryptionManager.java
index 0d48b5b..1fcdfa5 100644
--- a/securedpreferencestore/src/main/java/devliving/online/securedpreferencestore/EncryptionManager.java
+++ b/securedpreferencestore/src/main/java/devliving/online/securedpreferencestore/EncryptionManager.java
@@ -998,4 +998,4 @@ public InvalidMacException() {
             super("Invalid Mac, failed to verify integrity.");
         }
     }
-}
+}
\ No newline at end of file
diff --git a/securedpreferencestore/src/main/java/devliving/online/securedpreferencestore/SecuredPreferenceStore.java b/securedpreferencestore/src/main/java/devliving/online/securedpreferencestore/SecuredPreferenceStore.java
index a5db5f9..653a0d2 100644
--- a/securedpreferencestore/src/main/java/devliving/online/securedpreferencestore/SecuredPreferenceStore.java
+++ b/securedpreferencestore/src/main/java/devliving/online/securedpreferencestore/SecuredPreferenceStore.java
@@ -5,6 +5,7 @@
 import android.os.Build;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
+import android.util.Log;
 
 import java.io.File;
 import java.io.IOException;
@@ -32,6 +33,9 @@
  * Created by Mehedi on 8/21/16.
  */
 public class SecuredPreferenceStore implements SharedPreferences {
+    static final int DELAY = 100;                     // in nano seconds
+    static final int MAX_RETRY_COUNT = 3;
+
     private final static int[] VERSIONS_WITH_BREAKING_CHANGES = new int[]{10}; //version code in ascending order
     final static String VERSION_KEY = "VERSION";
     private final static String DEFAULT_PREF_FILE_NAME = "SPS_file";
@@ -45,6 +49,7 @@ public class SecuredPreferenceStore implements SharedPreferences {
 
     private static SecuredPreferenceStore mInstance;
 
+
     /**
      *
      * @param appContext application context
@@ -186,45 +191,92 @@ public Map<String, Object> getAll() {
     }
 
     @Override
-    public String getString(String key, String defValue) {
+    public String getString(final String key, final String defValue) {
         if(!isReservedKey(key)) {
-            try {
-                String hashedKey = EncryptionManager.getHashed(key);
-                String value = mPrefs.getString(hashedKey, null);
-                if (value != null) return mEncryptionManager.decrypt(value);
-            } catch (Exception e) {
-                Logger.e(e);
+            synchronized (SecuredPreferenceStore.class) {
+                return retryFunction(new Function<Void, String>() {
+                    @Override
+                    public String apply(Void t) throws Exception {
+                        String hashedKey = EncryptionManager.getHashed(key);
+                        String value = mPrefs.getString(hashedKey, null);
+                        return value == null ? defValue : mEncryptionManager.decrypt(value);
+                    }
+                }, null, defValue);
             }
+        } else {
+            return defValue;
         }
-
-        return defValue;
     }
 
     @Override
-    public Set<String> getStringSet(String key, Set<String> defValues) {
+    public Set<String> getStringSet(final String key, final Set<String> defValues) {
         if(!isReservedKey(key)) {
-            try {
-                String hashedKey = EncryptionManager.getHashed(key);
-                Set<String> eSet = mPrefs.getStringSet(hashedKey, null);
-
-                if (eSet != null) {
-                    Set<String> dSet = new HashSet<>(eSet.size());
+            synchronized (SecuredPreferenceStore.class) {
+                return retryFunction(new Function<Void, Set<String>>() {
+                    @Override
+                    public Set<String> apply(Void t) throws Exception {
+                        String hashedKey = EncryptionManager.getHashed(key);
+                        Set<String> eSet = mPrefs.getStringSet(hashedKey, null);
+
+                        if (eSet != null) {
+                            Set<String> dSet = new HashSet<>(eSet.size());
+
+                            for (String val : eSet) {
+                                dSet.add(mEncryptionManager.decrypt(val));
+                            }
 
-                    for (String val : eSet) {
-                        dSet.add(mEncryptionManager.decrypt(val));
+                            return dSet;
+                        } else {
+                            return defValues;
+                        }
                     }
-
-                    return dSet;
-                }
-
-            } catch (Exception e) {
-                Logger.e(e);
+                }, null, defValues);
             }
+        } else {
+            return defValues;
         }
-
-        return defValues;
     }
 
+//    @Override
+//    public String getString(String key, String defValue) {
+//        if(!isReservedKey(key)) {
+//            try {
+//                String hashedKey = EncryptionManager.getHashed(key);
+//                String value = mPrefs.getString(hashedKey, null);
+//                if (value != null) return mEncryptionManager.decrypt(value);
+//            } catch (Exception e) {
+//                Logger.e(e);
+//            }
+//        }
+//
+//        return defValue;
+//    }
+//
+//    @Override
+//    public Set<String> getStringSet(String key, Set<String> defValues) {
+//        if(!isReservedKey(key)) {
+//            try {
+//                String hashedKey = EncryptionManager.getHashed(key);
+//                Set<String> eSet = mPrefs.getStringSet(hashedKey, null);
+//
+//                if (eSet != null) {
+//                    Set<String> dSet = new HashSet<>(eSet.size());
+//
+//                    for (String val : eSet) {
+//                        dSet.add(mEncryptionManager.decrypt(val));
+//                    }
+//
+//                    return dSet;
+//                }
+//
+//            } catch (Exception e) {
+//                Logger.e(e);
+//            }
+//        }
+//
+//        return defValues;
+//    }
+
     @Override
     public int getInt(String key, int defValue) {
         String value = getString(key, null);
@@ -299,6 +351,30 @@ public void unregisterOnSharedPreferenceChangeListener(OnSharedPreferenceChangeL
             mPrefs.unregisterOnSharedPreferenceChangeListener(onSharedPreferenceChangeListener);
     }
 
+    protected <T, R> R retryFunction(Function<T, R> function, T t, R r) {
+        int retryCount = 0;
+        do {
+            try {
+                return function.apply(t);
+            } catch (Exception e) {
+//                e.printStackTrace();
+                retryCount++;
+                try {
+                    Log.d("queen", Thread.currentThread().getName() + ", retryCount " + retryCount);
+                    Thread.sleep(0,DELAY * retryCount);
+                } catch (Exception ee) {
+                    ee.printStackTrace();
+                }
+
+                if(retryCount == MAX_RETRY_COUNT) {   // let's give up. no more retry.
+                    Log.e(SecuredPreferenceStore.class.getName(), "cannot access keystore");
+                }
+            }
+        } while (retryCount >= MAX_RETRY_COUNT);
+
+        return r;
+    }
+
     public class Editor implements SharedPreferences.Editor {
         SharedPreferences.Editor mEditor;
 
@@ -306,45 +382,95 @@ public Editor() {
             mEditor = mPrefs.edit();
         }
 
+//        @Override
+//        public SharedPreferences.Editor putString(String key, String value) {
+//            if(isReservedKey(key)) {
+//                Logger.e("Trying to store value for a reserved key, value: " + value);
+//                return this;
+//            }
+//
+//            try {
+//                String hashedKey = EncryptionManager.getHashed(key);
+//                String evalue = mEncryptionManager.encrypt(value);
+//                mEditor.putString(hashedKey, evalue);
+//            } catch (Exception e) {
+//                Logger.e(e);
+//            }
+//
+//            return this;
+//        }
+//
+//        @Override
+//        public SharedPreferences.Editor putStringSet(String key, Set<String> values) {
+//            if(isReservedKey(key)) {
+//                Logger.e("Trying to store value for a reserved key, value: " + values);
+//                return this;
+//            }
+//
+//            try {
+//                String hashedKey = EncryptionManager.getHashed(key);
+//                Set<String> eSet = new HashSet<String>(values.size());
+//
+//                for (String val : values) {
+//                    eSet.add(mEncryptionManager.encrypt(val));
+//                }
+//
+//                mEditor.putStringSet(hashedKey, eSet);
+//            } catch (Exception e) {
+//                Logger.e(e);
+//            }
+//
+//            return this;
+//        }
+
         @Override
-        public SharedPreferences.Editor putString(String key, String value) {
+        public SharedPreferences.Editor putString(final String key, final String value) {
             if(isReservedKey(key)) {
                 Logger.e("Trying to store value for a reserved key, value: " + value);
                 return this;
             }
 
-            try {
-                String hashedKey = EncryptionManager.getHashed(key);
-                String evalue = mEncryptionManager.encrypt(value);
-                mEditor.putString(hashedKey, evalue);
-            } catch (Exception e) {
-                Logger.e(e);
-            }
+            synchronized (SecuredPreferenceStore.class) {
+                retryFunction(new Function<Void, Void>() {
+                    @Override
+                    public Void apply(Void t) throws Exception {
+                        String hashedKey = EncryptionManager.getHashed(key);
+                        String evalue = mEncryptionManager.encrypt(value);
+                        mEditor.putString(hashedKey, evalue);
+                        return null;
+                    }
+                }, null, null);
 
-            return this;
+                return this;
+            }
         }
 
         @Override
-        public SharedPreferences.Editor putStringSet(String key, Set<String> values) {
+        public SharedPreferences.Editor putStringSet(final String key,
+                                                                  final Set<String> values) {
             if(isReservedKey(key)) {
                 Logger.e("Trying to store value for a reserved key, value: " + values);
                 return this;
             }
 
-            try {
-                String hashedKey = EncryptionManager.getHashed(key);
-                Set<String> eSet = new HashSet<String>(values.size());
+            synchronized (SecuredPreferenceStore.class) {
+                retryFunction(new Function<Void, Void>() {
+                    @Override
+                    public Void apply(Void t) throws Exception {
+                        String hashedKey = EncryptionManager.getHashed(key);
+                        Set<String> eSet = new HashSet<String>(values.size());
 
-                for (String val : values) {
-                    eSet.add(mEncryptionManager.encrypt(val));
-                }
+                        for (String val : values) {
+                            eSet.add(mEncryptionManager.encrypt(val));
+                        }
 
-                mEditor.putStringSet(hashedKey, eSet);
-            } catch (Exception e) {
-                Logger.e(e);
-            }
+                        mEditor.putStringSet(hashedKey, eSet);
+                        return null;
+                    }
+                }, null, null);
 
-            return this;
+                return this;
+            }
         }
 
         @Override
@@ -428,6 +554,10 @@ public interface KeyStoreRecoveryNotifier{
         boolean onRecoveryRequired(Exception e, KeyStore keyStore, List<String> keyAliases);
     }
 
+    public interface Function<T, R> {
+        R apply(T t) throws Exception;
+    }
+
     //region Migration
     private class MigrationHelper {
         String storeName, keyPrefix;
@@ -591,4 +721,4 @@ public MigrationFailedException(String message, Throwable cause) {
         }
     }
     //endregion
-}
+}
\ No newline at end of file