diff --git a/V2rayNG/app/build.gradle b/V2rayNG/app/build.gradle
index a1ff9805..06356c83 100644
--- a/V2rayNG/app/build.gradle
+++ b/V2rayNG/app/build.gradle
@@ -84,6 +84,10 @@ dependencies {
     implementation project(':dpreference')
     implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlinVersion"
     implementation "org.jetbrains.kotlin:kotlin-reflect:$kotlinVersion"
+    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.2.2"
+    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:1.2.2" // 1.3.x has compile error:
+    // More than one file was found with OS independent path 'META-INF/proguard/coroutines.pro'
+
     // Android support library
     implementation "com.android.support:support-v4:$supportLibVersion"
     implementation "com.android.support:appcompat-v7:$supportLibVersion"
diff --git a/V2rayNG/app/src/main/kotlin/com/v2ray/ang/ui/MainActivity.kt b/V2rayNG/app/src/main/kotlin/com/v2ray/ang/ui/MainActivity.kt
index 65447d19..a872572c 100644
--- a/V2rayNG/app/src/main/kotlin/com/v2ray/ang/ui/MainActivity.kt
+++ b/V2rayNG/app/src/main/kotlin/com/v2ray/ang/ui/MainActivity.kt
@@ -33,6 +33,7 @@ import rx.android.schedulers.AndroidSchedulers
 import java.util.concurrent.TimeUnit
 import com.v2ray.ang.helper.SimpleItemTouchHelperCallback
 import com.v2ray.ang.util.AngConfigManager.configs
+import kotlinx.coroutines.*
 
 class MainActivity : BaseActivity(), NavigationView.OnNavigationItemSelectedListener {
     companion object {
@@ -58,6 +59,7 @@ class MainActivity : BaseActivity(), NavigationView.OnNavigationItemSelectedList
 
     private val adapter by lazy { MainRecyclerAdapter(this) }
     private var mItemTouchHelper: ItemTouchHelper? = null
+    private val testingJobs = ArrayList<Job>()
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -240,6 +242,10 @@ class MainActivity : BaseActivity(), NavigationView.OnNavigationItemSelectedList
         }
 
         R.id.ping_all -> {
+            testingJobs.forEach {
+                it.cancel()
+            }
+            testingJobs.clear()
             Utils.closeAllTcpSockets()
             for (k in 0 until configs.vmess.count()) {
                 configs.vmess[k].testResult = ""
@@ -247,12 +253,14 @@ class MainActivity : BaseActivity(), NavigationView.OnNavigationItemSelectedList
             }
             for (k in 0 until configs.vmess.count()) {
                 if (configs.vmess[k].configType != AppConfig.EConfigType.Custom) {
-                    doAsync {
+                    testingJobs.add(GlobalScope.launch(Dispatchers.IO) {
                         configs.vmess[k].testResult = Utils.tcping(configs.vmess[k].address, configs.vmess[k].port)
-                        uiThread {
+                        val myJob = coroutineContext[Job]
+                        launch(Dispatchers.Main) {
+                            testingJobs.remove(myJob)
                             adapter.updateSelectedItem(k)
                         }
-                    }
+                    })
                 }
             }
             true
@@ -571,4 +579,4 @@ class MainActivity : BaseActivity(), NavigationView.OnNavigationItemSelectedList
         drawer_layout.closeDrawer(GravityCompat.START)
         return true
     }
-}
\ No newline at end of file
+}
diff --git a/V2rayNG/app/src/main/kotlin/com/v2ray/ang/util/Utils.kt b/V2rayNG/app/src/main/kotlin/com/v2ray/ang/util/Utils.kt
index 0703105a..e50a0075 100644
--- a/V2rayNG/app/src/main/kotlin/com/v2ray/ang/util/Utils.kt
+++ b/V2rayNG/app/src/main/kotlin/com/v2ray/ang/util/Utils.kt
@@ -31,6 +31,7 @@ import com.v2ray.ang.extension.v2RayApplication
 import com.v2ray.ang.service.V2RayVpnService
 import com.v2ray.ang.ui.SettingsActivity
 import kotlinx.android.synthetic.main.activity_logcat.*
+import kotlinx.coroutines.isActive
 import me.dozen.dpreference.DPreference
 import org.jetbrains.anko.toast
 import org.jetbrains.anko.uiThread
@@ -44,6 +45,7 @@ import java.util.regex.Pattern
 import java.math.BigInteger
 import java.util.concurrent.TimeUnit
 import libv2ray.Libv2ray
+import kotlin.coroutines.coroutineContext
 
 
 object Utils {
@@ -485,10 +487,13 @@ object Utils {
     /**
      * tcping
      */
-    fun tcping(url: String, port: Int): String {
+    suspend fun tcping(url: String, port: Int): String {
         var time = -1L
         for (k in 0 until 2) {
             val one = socketConnectTime(url, port)
+            if (!coroutineContext.isActive) {
+                break
+            }
             if (one != -1L  )
                 if(time == -1L || one < time) {
                 time = one