diff --git a/app/src/main/java/io/legado/app/ui/main/MainActivity.kt b/app/src/main/java/io/legado/app/ui/main/MainActivity.kt
index 223448363..13b1f29b0 100644
--- a/app/src/main/java/io/legado/app/ui/main/MainActivity.kt
+++ b/app/src/main/java/io/legado/app/ui/main/MainActivity.kt
@@ -1,7 +1,6 @@
 package io.legado.app.ui.main
 
 import android.os.Bundle
-import android.util.Log
 import android.view.MenuItem
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.FragmentManager
@@ -26,8 +25,8 @@ import io.legado.app.utils.getCompatColor
 import io.legado.app.utils.getViewModel
 import kotlinx.android.synthetic.main.activity_main.*
 import kotlinx.coroutines.Dispatchers.IO
-import kotlinx.coroutines.Dispatchers.Main
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 
 class MainActivity : BaseActivity<MainViewModel>(), BottomNavigationView.OnNavigationItemSelectedListener,
     ViewPager.OnPageChangeListener {
@@ -63,15 +62,13 @@ class MainActivity : BaseActivity<MainViewModel>(), BottomNavigationView.OnNavig
     }
 
     private fun importYueDu() {
-        launch(IO) {
-            if (App.db.bookDao().allBookCount == 0) {
-                launch(Main) {
-                    PermissionsCompat.Builder(this@MainActivity)
-                        .addPermissions(*Permissions.Group.STORAGE)
-                        .rationale(R.string.tip_perm_request_storage)
-                        .onGranted { viewModel.restore() }
-                        .request()
-                }
+        launch {
+            if (withContext(IO) { App.db.bookDao().allBookCount == 0 }) {
+                PermissionsCompat.Builder(this@MainActivity)
+                    .addPermissions(*Permissions.Group.STORAGE)
+                    .rationale(R.string.tip_perm_request_storage)
+                    .onGranted { viewModel.restore() }
+                    .request()
             }
         }
     }
diff --git a/app/src/main/java/io/legado/app/ui/main/bookshelf/BookshelfFragment.kt b/app/src/main/java/io/legado/app/ui/main/bookshelf/BookshelfFragment.kt
index da5fe6bf0..e9b9c8653 100644
--- a/app/src/main/java/io/legado/app/ui/main/bookshelf/BookshelfFragment.kt
+++ b/app/src/main/java/io/legado/app/ui/main/bookshelf/BookshelfFragment.kt
@@ -21,7 +21,7 @@ import io.legado.app.ui.bookshelf.BookshelfActivity
 import io.legado.app.utils.disableAutoFill
 import kotlinx.android.synthetic.main.fragment_bookshelf.*
 import kotlinx.android.synthetic.main.view_title_bar.*
-import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.Dispatchers.IO
 import kotlinx.coroutines.launch
 import org.jetbrains.anko.startActivity
 import org.jetbrains.anko.textColor
@@ -88,7 +88,7 @@ class BookshelfFragment : BaseFragment(R.layout.fragment_bookshelf), BookGroupAd
                     title(text = "新建分组")
                     input(hint = "分组名称") { _, charSequence ->
                         run {
-                            GlobalScope.launch {
+                            launch(IO) {
                                 App.db.bookGroupDao().insert(
                                     BookGroup(
                                         App.db.bookGroupDao().maxId + 1,
diff --git a/app/src/main/java/io/legado/app/ui/main/booksource/BookSourceFragment.kt b/app/src/main/java/io/legado/app/ui/main/booksource/BookSourceFragment.kt
index 90b75c4d4..b07dc48d9 100644
--- a/app/src/main/java/io/legado/app/ui/main/booksource/BookSourceFragment.kt
+++ b/app/src/main/java/io/legado/app/ui/main/booksource/BookSourceFragment.kt
@@ -21,7 +21,7 @@ import io.legado.app.ui.qrcode.QrCodeActivity
 import io.legado.app.ui.sourceedit.SourceEditActivity
 import kotlinx.android.synthetic.main.fragment_book_source.*
 import kotlinx.android.synthetic.main.view_title_bar.*
-import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.Dispatchers.IO
 import kotlinx.coroutines.launch
 import org.jetbrains.anko.startActivity
 
@@ -99,15 +99,15 @@ class BookSourceFragment : BaseFragment(R.layout.fragment_book_source), BookSour
     }
 
     override fun del(bookSource: BookSource) {
-        GlobalScope.launch { App.db.bookSourceDao().delete(bookSource) }
+        launch(IO) { App.db.bookSourceDao().delete(bookSource) }
     }
 
     override fun update(bookSource: BookSource) {
-        GlobalScope.launch { App.db.bookSourceDao().update(bookSource) }
+        launch(IO) { App.db.bookSourceDao().update(bookSource) }
     }
 
     override fun update(vararg bookSource: BookSource) {
-        GlobalScope.launch { App.db.bookSourceDao().update(*bookSource) }
+        launch(IO) { App.db.bookSourceDao().update(*bookSource) }
     }
 
     override fun edit(bookSource: BookSource) {
diff --git a/app/src/main/java/io/legado/app/ui/sourceedit/SourceEditActivity.kt b/app/src/main/java/io/legado/app/ui/sourceedit/SourceEditActivity.kt
index 68a0d71df..bc7aabeec 100644
--- a/app/src/main/java/io/legado/app/ui/sourceedit/SourceEditActivity.kt
+++ b/app/src/main/java/io/legado/app/ui/sourceedit/SourceEditActivity.kt
@@ -10,9 +10,9 @@ import io.legado.app.base.BaseActivity
 import io.legado.app.data.entities.BookSource
 import io.legado.app.utils.getViewModel
 import kotlinx.android.synthetic.main.activity_source_edit.*
-import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.Dispatchers.IO
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 import org.jetbrains.anko.toast
 
 class SourceEditActivity : BaseActivity<SourceEditViewModel>() {
@@ -53,9 +53,9 @@ class SourceEditActivity : BaseActivity<SourceEditViewModel>() {
                 if (bookSource == null) {
                     toast("书源名称和URL不能为空")
                 } else {
-                    GlobalScope.launch {
-                        viewModel.save(bookSource)
-                        GlobalScope.launch(Dispatchers.Main) { finish() }
+                    launch {
+                        withContext(IO) { viewModel.save(bookSource) }
+                        finish()
                     }
                 }
             }