diff --git a/.idea/caches/build_file_checksums.ser b/.idea/caches/build_file_checksums.ser
index 3d334265..f1d03afc 100644
Binary files a/.idea/caches/build_file_checksums.ser and b/.idea/caches/build_file_checksums.ser differ
diff --git a/.idea/dictionaries/ganfra.xml b/.idea/dictionaries/ganfra.xml
index a9343c03..806a1048 100644
--- a/.idea/dictionaries/ganfra.xml
+++ b/.idea/dictionaries/ganfra.xml
@@ -1,7 +1,9 @@
 <component name="ProjectDictionaryState">
   <dictionary name="ganfra">
     <words>
+      <w>connectable</w>
       <w>coroutine</w>
+      <w>merlins</w>
       <w>moshi</w>
       <w>synchronizer</w>
     </words>
diff --git a/app/src/main/java/im/vector/riotredesign/features/home/HomeActivity.kt b/app/src/main/java/im/vector/riotredesign/features/home/HomeActivity.kt
index 56d391fe..07f3be3e 100644
--- a/app/src/main/java/im/vector/riotredesign/features/home/HomeActivity.kt
+++ b/app/src/main/java/im/vector/riotredesign/features/home/HomeActivity.kt
@@ -3,53 +3,31 @@ package im.vector.riotredesign.features.home
 import android.content.Context
 import android.content.Intent
 import android.os.Bundle
-import android.view.View
 import im.vector.matrix.android.api.Matrix
-import im.vector.matrix.android.api.MatrixCallback
-import im.vector.matrix.android.api.failure.Failure
 import im.vector.matrix.android.internal.database.model.RoomSummaryEntity
-import im.vector.matrix.android.internal.events.sync.data.SyncResponse
 import im.vector.riotredesign.R
 import im.vector.riotredesign.core.platform.RiotActivity
 import kotlinx.android.synthetic.main.activity_home.*
 import org.koin.android.ext.android.inject
 import timber.log.Timber
 
+
 class HomeActivity : RiotActivity() {
 
     private val matrix by inject<Matrix>()
-    private val synchronizer = matrix.currentSession?.synchronizer()
-    private val realmHolder = matrix.currentSession?.realmHolder()
+    private val currentSession = matrix.currentSession!!
+    private val realmHolder = currentSession.realmHolder()
+    private val syncThread = currentSession.syncThread()
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_home)
-        synchronizeButton.setOnClickListener { synchronize() }
-    }
-
-    private fun synchronize() {
-        synchronizeButton.visibility = View.GONE
-        loadingView.visibility = View.VISIBLE
-        synchronizer?.synchronize(object : MatrixCallback<SyncResponse> {
-            override fun onSuccess(data: SyncResponse) {
-                synchronizeButton.visibility = View.VISIBLE
-                loadingView.visibility = View.GONE
-                Timber.v("Sync successful")
-            }
-
-            override fun onFailure(failure: Failure) {
-                synchronizeButton.visibility = View.VISIBLE
-                loadingView.visibility = View.GONE
-                Timber.e("Sync has failed : %s", failure.toString())
-            }
-        })
-        if (realmHolder != null) {
-            val results = realmHolder.instance.where(RoomSummaryEntity::class.java).findAll()
-            results.addChangeListener { summaries ->
-                Timber.v("Summaries updated")
-            }
+        val results = realmHolder.instance.where(RoomSummaryEntity::class.java).findAll()
+        results.addChangeListener { summaries ->
+            Timber.v("Summaries updated")
         }
-
+        startSyncButton.setOnClickListener { syncThread.restart() }
+        stopSyncButton.setOnClickListener { syncThread.pause() }
     }
 
     companion object {
diff --git a/app/src/main/res/layout/activity_home.xml b/app/src/main/res/layout/activity_home.xml
index 3078248e..e5007dce 100644
--- a/app/src/main/res/layout/activity_home.xml
+++ b/app/src/main/res/layout/activity_home.xml
@@ -7,34 +7,34 @@
     android:orientation="vertical"
     tools:context=".features.login.LoginActivity">
 
-    <ProgressBar
-        android:id="@+id/loadingView"
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
+    <Button
+        android:id="@+id/startSyncButton"
+        android:layout_width="0dp"
+        android:layout_height="0dp"
         android:layout_marginBottom="8dp"
         android:layout_marginEnd="8dp"
         android:layout_marginStart="8dp"
         android:layout_marginTop="8dp"
-        android:visibility="gone"
-        app:layout_constraintBottom_toBottomOf="parent"
+        android:text="Start sync"
+        app:layout_constraintBottom_toTopOf="@+id/stopSyncButton"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toTopOf="parent" />
 
-
     <Button
-        android:id="@+id/synchronizeButton"
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
+        android:id="@+id/stopSyncButton"
+        android:layout_width="0dp"
+        android:layout_height="0dp"
         android:layout_marginBottom="8dp"
         android:layout_marginEnd="8dp"
         android:layout_marginStart="8dp"
         android:layout_marginTop="8dp"
-        android:text="Synchronize"
+        android:text="stop sync"
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.5"
         app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toTopOf="parent" />
+        app:layout_constraintTop_toBottomOf="@+id/startSyncButton" />
 
 
 </android.support.constraint.ConstraintLayout>
\ No newline at end of file
diff --git a/matrix-sdk-android/build.gradle b/matrix-sdk-android/build.gradle
index 905877d0..7e1402ba 100644
--- a/matrix-sdk-android/build.gradle
+++ b/matrix-sdk-android/build.gradle
@@ -45,6 +45,7 @@ dependencies {
     def support_version = '28.0.0'
     def moshi_version = '1.7.0'
     def lifecycle_version = "1.1.1"
+    def work_version = "1.0.0-alpha10"
 
     implementation fileTree(dir: 'libs', include: ['*.aar'])
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
@@ -55,7 +56,6 @@ dependencies {
     implementation "android.arch.lifecycle:extensions:$lifecycle_version"
     kapt "android.arch.lifecycle:compiler:$lifecycle_version"
 
-
     // Network
     implementation 'com.squareup.retrofit2:retrofit:2.4.0'
     implementation 'com.squareup.retrofit2:converter-moshi:2.4.0'
@@ -64,6 +64,7 @@ dependencies {
     implementation 'com.squareup.okhttp3:okhttp:3.10.0'
     implementation 'com.squareup.okhttp3:logging-interceptor:3.10.0'
     implementation 'com.squareup.okio:okio:1.15.0'
+    implementation 'com.novoda:merlin:1.1.6'
 
     implementation 'com.google.code.gson:gson:2.8.5'
     implementation "com.squareup.moshi:moshi-adapters:$moshi_version"
@@ -72,6 +73,10 @@ dependencies {
     // Paging
     implementation "android.arch.paging:runtime:1.0.1"
 
+    // Worker
+    implementation "android.arch.work:work-runtime-ktx:$work_version"
+    implementation 'com.evernote:android-job:1.2.6'
+
     implementation "io.arrow-kt:arrow-core:$arrow_version"
 
     // DI
diff --git a/matrix-sdk-android/src/main/AndroidManifest.xml b/matrix-sdk-android/src/main/AndroidManifest.xml
index 8139d75a..44b519b0 100644
--- a/matrix-sdk-android/src/main/AndroidManifest.xml
+++ b/matrix-sdk-android/src/main/AndroidManifest.xml
@@ -1,5 +1,6 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="im.vector.matrix.android" >
 
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
     <uses-permission android:name="android.permission.VIBRATE" />
 </manifest>
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/Matrix.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/Matrix.kt
index 7af58b9b..83852976 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/Matrix.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/Matrix.kt
@@ -1,7 +1,7 @@
 package im.vector.matrix.android.api
 
 import android.content.Context
-import im.vector.matrix.android.BuildConfig
+import com.evernote.android.job.JobManager
 import im.vector.matrix.android.api.auth.Authenticator
 import im.vector.matrix.android.api.session.Session
 import im.vector.matrix.android.internal.auth.AuthModule
@@ -11,8 +11,6 @@ import io.realm.Realm
 import org.koin.standalone.KoinComponent
 import org.koin.standalone.StandAloneContext.loadKoinModules
 import org.koin.standalone.inject
-import timber.log.Timber
-import timber.log.Timber.DebugTree
 
 
 class Matrix(matrixOptions: MatrixOptions) : KoinComponent {
@@ -23,13 +21,11 @@ class Matrix(matrixOptions: MatrixOptions) : KoinComponent {
 
     init {
         Realm.init(matrixOptions.context)
+        JobManager.create(matrixOptions.context)
         val matrixModule = MatrixModule(matrixOptions)
         val networkModule = NetworkModule()
         val authModule = AuthModule()
         loadKoinModules(listOf(matrixModule, networkModule, authModule))
-        if (BuildConfig.DEBUG) {
-            Timber.plant(DebugTree())
-        }
     }
 
     fun authenticator(): Authenticator {
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/Session.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/Session.kt
index d1fa6bb9..cacf786d 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/Session.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/Session.kt
@@ -2,14 +2,14 @@ package im.vector.matrix.android.api.session
 
 import android.support.annotation.MainThread
 import im.vector.matrix.android.internal.database.SessionRealmHolder
-import im.vector.matrix.android.internal.events.sync.Synchronizer
+import im.vector.matrix.android.internal.events.sync.job.SyncThread
 
 interface Session {
 
     @MainThread
     fun open()
 
-    fun synchronizer(): Synchronizer
+    fun syncThread(): SyncThread
 
     // Visible for testing request directly. Will be deleted
     fun realmHolder(): SessionRealmHolder
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/util/Logger.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/util/Logger.kt
deleted file mode 100644
index 2c78e9f5..00000000
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/util/Logger.kt
+++ /dev/null
@@ -1,57 +0,0 @@
-package im.vector.matrix.android.api.util
-
-interface Logger {
-    /** Log a verbose message with optional format args.  */
-    fun v(message: String, vararg args: Any)
-
-    /** Log a verbose exception and a message with optional format args.  */
-    fun v(t: Throwable, message: String, vararg args: Any)
-
-    /** Log a verbose exception.  */
-    fun v(t: Throwable)
-
-    /** Log a debug message with optional format args.  */
-    fun d(message: String, vararg args: Any)
-
-    /** Log a debug exception and a message with optional format args.  */
-    fun d(t: Throwable, message: String, vararg args: Any)
-
-    /** Log a debug exception.  */
-    fun d(t: Throwable)
-
-    /** Log an info message with optional format args.  */
-    fun i(message: String, vararg args: Any)
-
-    /** Log an info exception and a message with optional format args.  */
-    fun i(t: Throwable, message: String, vararg args: Any)
-
-    /** Log an info exception.  */
-    fun i(t: Throwable)
-
-    /** Log a warning message with optional format args.  */
-    fun w(message: String, vararg args: Any)
-
-    /** Log a warning exception and a message with optional format args.  */
-    fun w(t: Throwable, message: String, vararg args: Any)
-
-    /** Log a warning exception.  */
-    fun w(t: Throwable)
-
-    /** Log an error message with optional format args.  */
-    fun e(message: String, vararg args: Any)
-
-    /** Log an error exception and a message with optional format args.  */
-    fun e(t: Throwable, message: String, vararg args: Any)
-
-    /** Log an error exception.  */
-    fun e(t: Throwable)
-
-    /** Log an assert message with optional format args.  */
-    fun wtf(message: String, vararg args: Any)
-
-    /** Log an assert exception and a message with optional format args.  */
-    fun wtf(t: Throwable, message: String, vararg args: Any)
-
-    /** Log an assert exception.  */
-    fun wtf(t: Throwable)
-}
\ No newline at end of file
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/database/mapper/EventMapper.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/database/mapper/EventMapper.kt
index 9ccc9307..05b25dbb 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/database/mapper/EventMapper.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/database/mapper/EventMapper.kt
@@ -15,7 +15,7 @@ object EventMapper {
 
     internal fun map(event: Event): EventEntity {
         val eventEntity = EventEntity()
-        eventEntity.eventId = event.eventId!!
+        eventEntity.eventId = event.eventId ?: ""
         eventEntity.content = adapter.toJson(event.content)
         eventEntity.prevContent = adapter.toJson(event.prevContent)
         eventEntity.stateKey = event.stateKey
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/di/NetworkModule.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/di/NetworkModule.kt
index 9504b7b0..7300242d 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/di/NetworkModule.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/di/NetworkModule.kt
@@ -2,6 +2,7 @@ package im.vector.matrix.android.internal.di
 
 import com.jakewharton.retrofit2.adapter.kotlin.coroutines.CoroutineCallAdapterFactory
 import im.vector.matrix.android.internal.network.AccessTokenInterceptor
+import im.vector.matrix.android.internal.network.NetworkConnectivityChecker
 import okhttp3.OkHttpClient
 import okhttp3.logging.HttpLoggingInterceptor
 import org.koin.dsl.context.ModuleDefinition
@@ -49,6 +50,10 @@ class NetworkModule : Module {
             CoroutineCallAdapterFactory() as CallAdapter.Factory
         }
 
+        single {
+            NetworkConnectivityChecker(get())
+        }
+
         factory {
             Retrofit.Builder()
                     .client(get())
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/events/sync/RoomSyncHandler.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/events/sync/RoomSyncHandler.kt
index a96c73d3..070247fd 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/events/sync/RoomSyncHandler.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/events/sync/RoomSyncHandler.kt
@@ -104,6 +104,7 @@ class RoomSyncHandler(private val realmConfiguration: RealmConfiguration) {
 
         chunkEntity.nextToken = nextToken
         chunkEntity.isLimited = isLimited
+
         eventList.forEach { event ->
             val eventEntity = event.asEntity().let {
                 realm.copyToRealmOrUpdate(it)
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/events/sync/StateEvent.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/events/sync/StateEvent.kt
deleted file mode 100644
index 602f6dcd..00000000
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/events/sync/StateEvent.kt
+++ /dev/null
@@ -1,18 +0,0 @@
-package im.vector.matrix.android.internal.events.sync
-
-import com.squareup.moshi.Json
-import com.squareup.moshi.JsonClass
-
-@JsonClass(generateAdapter = true)
-data class StateEvent(
-        @Json(name = "name") val name: String? = null,
-        @Json(name = "topic") val topic: String? = null,
-        @Json(name = "join_rule") val joinRule: String? = null,
-        @Json(name = "guest_access") val guestAccess: String? = null,
-        @Json(name = "alias") val canonicalAlias: String? = null,
-        @Json(name = "aliases") val aliases: List<String>? = null,
-        @Json(name = "algorithm") val algorithm: String? = null,
-        @Json(name = "history_visibility") val historyVisibility: String? = null,
-        @Json(name = "url") val url: String? = null,
-        @Json(name = "groups") val groups: List<String>? = null
-)
\ No newline at end of file
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/events/sync/SyncModule.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/events/sync/SyncModule.kt
index cea92d7f..3c545172 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/events/sync/SyncModule.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/events/sync/SyncModule.kt
@@ -1,11 +1,13 @@
 package im.vector.matrix.android.internal.events.sync
 
+import im.vector.matrix.android.internal.events.sync.job.SyncThread
 import im.vector.matrix.android.internal.session.DefaultSession
 import org.koin.dsl.context.ModuleDefinition
 import org.koin.dsl.module.Module
 import org.koin.dsl.module.module
 import retrofit2.Retrofit
 
+
 class SyncModule : Module {
 
     override fun invoke(): ModuleDefinition = module(override = true) {
@@ -24,8 +26,13 @@ class SyncModule : Module {
         }
 
         scope(DefaultSession.SCOPE) {
-            Synchronizer(get(), get(), get())
+            SyncRequest(get(), get(), get())
         }
 
+        scope(DefaultSession.SCOPE) {
+            SyncThread(get(), get())
+        }
+
+
     }.invoke()
 }
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/events/sync/Synchronizer.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/events/sync/SyncRequest.kt
similarity index 78%
rename from matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/events/sync/Synchronizer.kt
rename to matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/events/sync/SyncRequest.kt
index c8348370..69a034d8 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/events/sync/Synchronizer.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/events/sync/SyncRequest.kt
@@ -16,28 +16,27 @@ import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 
-class Synchronizer(private val syncAPI: SyncAPI,
-                   private val coroutineDispatchers: MatrixCoroutineDispatchers,
-                   private val syncResponseHandler: SyncResponseHandler) {
+class SyncRequest(private val syncAPI: SyncAPI,
+                  private val coroutineDispatchers: MatrixCoroutineDispatchers,
+                  private val syncResponseHandler: SyncResponseHandler) {
 
-    private var token: String? = null
 
-    fun synchronize(callback: MatrixCallback<SyncResponse>): Cancelable {
+    fun execute(token: String?, callback: MatrixCallback<SyncResponse>): Cancelable {
         val job = GlobalScope.launch(coroutineDispatchers.main) {
-            val syncOrFailure = synchronize()
+            val syncOrFailure = execute(token)
             syncOrFailure.bimap({ callback.onFailure(it) }, { callback.onSuccess(it) })
         }
         return CancelableCoroutine(job)
     }
 
-    private suspend fun synchronize() = withContext(coroutineDispatchers.io) {
+    private suspend fun execute(token: String?) = withContext(coroutineDispatchers.io) {
         val params = HashMap<String, String>()
         val filterBody = FilterBody()
         FilterUtil.enableLazyLoading(filterBody, true)
         var timeout = 0
         if (token != null) {
             params["since"] = token as String
-            timeout = 30
+            timeout = 30000
         }
         params["timeout"] = timeout.toString()
         params["filter"] = filterBody.toJSONString()
@@ -46,7 +45,6 @@ class Synchronizer(private val syncAPI: SyncAPI,
         }.leftIfNull {
             Failure.Unknown(RuntimeException("Sync response shouln't be null"))
         }.flatMap {
-            token = it?.nextBatch
             try {
                 syncResponseHandler.handleResponse(it, null, false)
                 Either.right(it)
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/events/sync/job/SyncThread.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/events/sync/job/SyncThread.kt
new file mode 100644
index 00000000..623517be
--- /dev/null
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/events/sync/job/SyncThread.kt
@@ -0,0 +1,105 @@
+package im.vector.matrix.android.internal.events.sync.job
+
+import im.vector.matrix.android.api.MatrixCallback
+import im.vector.matrix.android.api.failure.Failure
+import im.vector.matrix.android.api.util.Cancelable
+import im.vector.matrix.android.internal.events.sync.SyncRequest
+import im.vector.matrix.android.internal.events.sync.data.SyncResponse
+import im.vector.matrix.android.internal.network.NetworkConnectivityChecker
+import timber.log.Timber
+import java.util.concurrent.CountDownLatch
+
+private const val RETRY_WAIT_TIME_MS = 10_000L
+
+class SyncThread(private val syncRequest: SyncRequest,
+                 private val networkConnectivityChecker: NetworkConnectivityChecker
+) : Thread(), NetworkConnectivityChecker.Listener {
+
+    enum class State {
+        IDLE,
+        RUNNING,
+        PAUSED,
+        KILLING,
+        KILLED
+    }
+
+    private var state: State = State.IDLE
+    private val lock = Object()
+    private var nextBatch: String? = null
+    private var cancelableRequest: Cancelable? = null
+
+    fun restart() {
+        synchronized(lock) {
+            if (state != State.PAUSED) {
+                return@synchronized
+            }
+            Timber.v("Unpause sync...")
+            state = State.RUNNING
+            lock.notify()
+        }
+    }
+
+    fun pause() {
+        synchronized(lock) {
+            if (state != State.RUNNING) {
+                return@synchronized
+            }
+            Timber.v("Pause sync...")
+            state = State.PAUSED
+        }
+    }
+
+    fun kill() {
+        synchronized(lock) {
+            Timber.v("Kill sync...")
+            state = State.KILLING
+            cancelableRequest?.cancel()
+            lock.notify()
+        }
+    }
+
+
+    override fun run() {
+        Timber.v("Start syncing...")
+        state = State.RUNNING
+        networkConnectivityChecker.register(this)
+        while (state != State.KILLING) {
+            if (!networkConnectivityChecker.isConnected() || state == State.PAUSED) {
+                Timber.v("Waiting...")
+                synchronized(lock) {
+                    lock.wait()
+                }
+            } else {
+                Timber.v("Execute sync request...")
+                val latch = CountDownLatch(1)
+                cancelableRequest = syncRequest.execute(nextBatch, object : MatrixCallback<SyncResponse> {
+                    override fun onSuccess(data: SyncResponse) {
+                        nextBatch = data.nextBatch
+                        latch.countDown()
+                    }
+
+                    override fun onFailure(failure: Failure) {
+                        if (failure !is Failure.NetworkConnection) {
+                            // Wait 10s before retrying
+                            sleep(RETRY_WAIT_TIME_MS)
+                        }
+                        latch.countDown()
+                    }
+                })
+                latch.await()
+            }
+        }
+        Timber.v("Sync killed")
+        state = State.KILLED
+        networkConnectivityChecker.unregister(this)
+    }
+
+    override fun onConnect() {
+        synchronized(lock) {
+            lock.notify()
+        }
+    }
+
+}
+
+
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/legacy/MXSession.java b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/legacy/MXSession.java
index ac0be7bb..9a8ceab6 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/legacy/MXSession.java
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/legacy/MXSession.java
@@ -1075,7 +1075,7 @@ public class MXSession {
         }
 
         if (null != mEventsThread) {
-            Log.d(LOG_TAG, "## resumeEventStream() : unpause");
+            Log.d(LOG_TAG, "## resumeEventStream() : pickUp");
             mEventsThread.unpause();
         } else {
             Log.e(LOG_TAG, "resumeEventStream : mEventsThread is null");
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/legacy/sync/EventsThread.java b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/legacy/sync/EventsThread.java
index 9c580b14..dfef023a 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/legacy/sync/EventsThread.java
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/legacy/sync/EventsThread.java
@@ -228,7 +228,7 @@ public class EventsThread extends Thread {
     }
 
     /**
-     * Pause the thread. It will resume where it left off when unpause()d.
+     * Pause the thread. It will resume where it left off when pickUp()d.
      */
     public void pause() {
         Log.d(LOG_TAG, "pause()");
@@ -264,10 +264,10 @@ public class EventsThread extends Thread {
      * Unpause the thread if it had previously been paused. If not, this does nothing.
      */
     public void unpause() {
-        Log.d(LOG_TAG, "## unpause() : thread state " + getState());
+        Log.d(LOG_TAG, "## pickUp() : thread state " + getState());
 
         if (State.WAITING == getState()) {
-            Log.d(LOG_TAG, "## unpause() : the thread was paused so resume it.");
+            Log.d(LOG_TAG, "## pickUp() : the thread was paused so resume it.");
 
             mPaused = false;
             synchronized (mSyncObject) {
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/network/NetworkConnectivityChecker.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/network/NetworkConnectivityChecker.kt
new file mode 100644
index 00000000..588cc05d
--- /dev/null
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/network/NetworkConnectivityChecker.kt
@@ -0,0 +1,44 @@
+package im.vector.matrix.android.internal.network
+
+import android.content.Context
+import com.novoda.merlin.Merlin
+import com.novoda.merlin.MerlinsBeard
+import com.novoda.merlin.registerable.connection.Connectable
+
+class NetworkConnectivityChecker(context: Context) {
+
+    private val merlin = Merlin.Builder().withConnectableCallbacks().build(context)
+    private val merlinsBeard = MerlinsBeard.from(context)
+
+    private val listeners = ArrayList<Listener>()
+
+    fun register(listener: Listener) {
+        if (listeners.isEmpty()) {
+            merlin.bind()
+        }
+        listeners.add(listener)
+        val connectable = Connectable {
+            if (listeners.contains(listener)) {
+                listener.onConnect()
+            }
+        }
+        merlin.registerConnectable(connectable)
+    }
+
+    fun unregister(listener: Listener) {
+        if (listeners.remove(listener) && listeners.isEmpty()) {
+            merlin.unbind()
+        }
+    }
+
+    fun isConnected(): Boolean {
+        return merlinsBeard.isConnected
+    }
+
+    interface Listener {
+        fun onConnect()
+    }
+
+
+}
+
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/DefaultSession.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/DefaultSession.kt
index 23e0bf5d..820ec2b0 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/DefaultSession.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/DefaultSession.kt
@@ -7,13 +7,14 @@ import im.vector.matrix.android.internal.auth.data.SessionParams
 import im.vector.matrix.android.internal.database.SessionRealmHolder
 import im.vector.matrix.android.internal.di.SessionModule
 import im.vector.matrix.android.internal.events.sync.SyncModule
-import im.vector.matrix.android.internal.events.sync.Synchronizer
+import im.vector.matrix.android.internal.events.sync.job.SyncThread
 import org.koin.core.scope.Scope
 import org.koin.standalone.KoinComponent
 import org.koin.standalone.StandAloneContext
 import org.koin.standalone.getKoin
 import org.koin.standalone.inject
 
+
 class DefaultSession(private val sessionParams: SessionParams) : Session, KoinComponent {
 
     companion object {
@@ -23,9 +24,8 @@ class DefaultSession(private val sessionParams: SessionParams) : Session, KoinCo
     private lateinit var scope: Scope
 
     private val realmInstanceHolder by inject<SessionRealmHolder>()
-    private val synchronizer by inject<Synchronizer>()
     private val roomSummaryObserver by inject<RoomSummaryObserver>()
-
+    private val syncThread by inject<SyncThread>()
     private var isOpen = false
 
     @MainThread
@@ -39,11 +39,7 @@ class DefaultSession(private val sessionParams: SessionParams) : Session, KoinCo
         scope = getKoin().getOrCreateScope(SCOPE)
         realmInstanceHolder.open()
         roomSummaryObserver.start()
-    }
-
-    override fun synchronizer(): Synchronizer {
-        assert(isOpen)
-        return synchronizer
+        syncThread.start()
     }
 
     override fun realmHolder(): SessionRealmHolder {
@@ -51,16 +47,24 @@ class DefaultSession(private val sessionParams: SessionParams) : Session, KoinCo
         return realmInstanceHolder
     }
 
+    override fun syncThread(): SyncThread {
+        assert(isOpen)
+        return syncThread
+    }
+
     @MainThread
     override fun close() {
         checkIsMainThread()
         assert(isOpen)
+        syncThread.kill()
         roomSummaryObserver.dispose()
         realmInstanceHolder.close()
         scope.close()
         isOpen = false
     }
 
+    // Private methods *****************************************************************************
+
     private fun checkIsMainThread() {
         if (Looper.myLooper() != Looper.getMainLooper()) {
             throw IllegalStateException("Should be called on main thread")