diff --git a/app/src/main/java/io/legado/app/ui/main/MainViewModel.kt b/app/src/main/java/io/legado/app/ui/main/MainViewModel.kt
index 252dad72e..c86abcd5b 100644
--- a/app/src/main/java/io/legado/app/ui/main/MainViewModel.kt
+++ b/app/src/main/java/io/legado/app/ui/main/MainViewModel.kt
@@ -25,14 +25,19 @@ import io.legado.app.model.CacheBook
 import io.legado.app.model.ReadBook
 import io.legado.app.model.webBook.WebBook
 import io.legado.app.service.CacheBookService
+import io.legado.app.utils.onEachParallel
 import io.legado.app.utils.postEvent
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.asCoroutineDispatcher
 import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.catch
+import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.flow.flow
+import kotlinx.coroutines.flow.onCompletion
+import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.isActive
 import kotlinx.coroutines.launch
 import java.util.LinkedList
-import java.util.concurrent.ConcurrentHashMap
 import java.util.concurrent.Executors
 import kotlin.math.min
 
@@ -41,7 +46,7 @@ class MainViewModel(application: Application) : BaseViewModel(application) {
     private var poolSize = min(threadCount, AppConst.MAX_THREAD)
     private var upTocPool = Executors.newFixedThreadPool(poolSize).asCoroutineDispatcher()
     private val waitUpTocBooks = LinkedList<String>()
-    private val onUpTocBooks = ConcurrentHashMap.newKeySet<String>()
+    private val onUpTocBooks = hashSetOf<String>()
     val onUpBooksLiveData = MutableLiveData<Int>()
     private var upTocJob: Job? = null
     private var cacheBookJob: Job? = null
@@ -101,86 +106,70 @@ class MainViewModel(application: Application) : BaseViewModel(application) {
         upPool()
         postUpBooksLiveData()
         upTocJob = viewModelScope.launch(upTocPool) {
-            while (isActive) {
-                when {
-                    waitUpTocBooks.isEmpty() -> {
-                        upTocJob?.cancel()
-                        upTocJob = null
-                    }
-
-                    onUpTocBooks.size < threadCount -> {
-                        updateToc()
-                    }
-
-                    else -> {
-                        delay(500)
-                    }
+            flow {
+                while (true) {
+                    emit(waitUpTocBooks.poll() ?: break)
                 }
-            }
+            }.onEach {
+                onUpTocBooks.add(it)
+                postEvent(EventBus.UP_BOOKSHELF, it)
+            }.onEachParallel(threadCount) {
+                updateToc(it)
+            }.onEach {
+                onUpTocBooks.remove(it)
+                postEvent(EventBus.UP_BOOKSHELF, it)
+                postUpBooksLiveData()
+            }.onCompletion {
+                upTocJob = null
+                if (it == null && cacheBookJob == null && !CacheBookService.isRun) {
+                    //所有目录更新完再开始缓存章节
+                    cacheBook()
+                }
+            }.catch {
+                AppLog.put("更新目录出错\n${it.localizedMessage}", it)
+            }.collect()
         }
     }
 
-    @Synchronized
-    private fun updateToc() {
-        val bookUrl = waitUpTocBooks.poll() ?: return
-        if (onUpTocBooks.contains(bookUrl)) {
-            postUpBooksLiveData()
-            return
-        }
-        val book = appDb.bookDao.getBook(bookUrl)
-        if (book == null) {
-            postUpBooksLiveData()
-            return
-        }
+    private suspend fun updateToc(bookUrl: String) {
+        val book = appDb.bookDao.getBook(bookUrl) ?: return
         val source = appDb.bookSourceDao.getBookSource(book.origin)
         if (source == null) {
             if (!book.isUpError) {
                 book.addType(BookType.updateError)
                 appDb.bookDao.update(book)
             }
-            postUpBooksLiveData()
             return
         }
-        upTocAdd(bookUrl)
-        execute(context = upTocPool, executeContext = upTocPool) {
-            kotlin.runCatching {
-                val oldBook = book.copy()
-                WebBook.runPreUpdateJs(source, book)
-                if (book.tocUrl.isBlank()) {
-                    WebBook.getBookInfoAwait(source, book)
-                }
-                val toc = WebBook.getChapterListAwait(source, book).getOrThrow()
-                book.sync(oldBook)
-                book.removeType(BookType.updateError)
-                if (book.bookUrl == bookUrl) {
-                    appDb.bookDao.update(book)
-                } else {
-                    upTocAdd(book.bookUrl)
-                    appDb.bookDao.insert(book)
-                    BookHelp.updateCacheFolder(oldBook, book)
-                }
-                appDb.bookChapterDao.delByBook(bookUrl)
-                appDb.bookChapterDao.insert(*toc.toTypedArray())
-                if (book.isSameNameAuthor(ReadBook.book)) {
-                    ReadBook.book = book
-                    ReadBook.chapterSize = book.totalChapterNum
-                }
-                addDownload(source, book)
-            }.onFailure {
-                AppLog.put("${book.name} 更新目录失败\n${it.localizedMessage}", it)
-                //这里可能因为时间太长书籍信息已经更改,所以重新获取
-                appDb.bookDao.getBook(book.bookUrl)?.let { book ->
-                    book.addType(BookType.updateError)
-                    appDb.bookDao.update(book)
-                }
+        kotlin.runCatching {
+            val oldBook = book.copy()
+            WebBook.runPreUpdateJs(source, book)
+            if (book.tocUrl.isBlank()) {
+                WebBook.getBookInfoAwait(source, book)
+            }
+            val toc = WebBook.getChapterListAwait(source, book).getOrThrow()
+            book.sync(oldBook)
+            book.removeType(BookType.updateError)
+            if (book.bookUrl == bookUrl) {
+                appDb.bookDao.update(book)
+            } else {
+                appDb.bookDao.insert(book)
+                BookHelp.updateCacheFolder(oldBook, book)
+            }
+            appDb.bookChapterDao.delByBook(bookUrl)
+            appDb.bookChapterDao.insert(*toc.toTypedArray())
+            if (book.isSameNameAuthor(ReadBook.book)) {
+                ReadBook.book = book
+                ReadBook.chapterSize = book.totalChapterNum
+            }
+            addDownload(source, book)
+        }.onFailure {
+            AppLog.put("${book.name} 更新目录失败\n${it.localizedMessage}", it)
+            //这里可能因为时间太长书籍信息已经更改,所以重新获取
+            appDb.bookDao.getBook(book.bookUrl)?.let { book ->
+                book.addType(BookType.updateError)
+                appDb.bookDao.update(book)
             }
-        }.onCancel {
-            upTocCancel(bookUrl)
-            upTocCancel(book.bookUrl)
-        }.onFinally {
-            upTocFinally(bookUrl)
-            upTocFinally(book.bookUrl)
-            postUpBooksLiveData()
         }
     }
 
@@ -192,33 +181,6 @@ class MainViewModel(application: Application) : BaseViewModel(application) {
         }
     }
 
-    @Synchronized
-    private fun upTocAdd(bookUrl: String) {
-        onUpTocBooks.add(bookUrl)
-        postEvent(EventBus.UP_BOOKSHELF, bookUrl)
-    }
-
-    @Synchronized
-    private fun upTocCancel(bookUrl: String) {
-        onUpTocBooks.remove(bookUrl)
-        waitUpTocBooks.add(bookUrl)
-        postEvent(EventBus.UP_BOOKSHELF, bookUrl)
-    }
-
-    @Synchronized
-    private fun upTocFinally(bookUrl: String) {
-        onUpTocBooks.remove(bookUrl)
-        postEvent(EventBus.UP_BOOKSHELF, bookUrl)
-        if (waitUpTocBooks.isEmpty()
-            && onUpTocBooks.isEmpty()
-            && cacheBookJob == null
-            && !CacheBookService.isRun
-        ) {
-            //所有目录更新完再开始缓存章节
-            cacheBook()
-        }
-    }
-
     @Synchronized
     private fun addDownload(source: BookSource, book: Book) {
         if (AppConfig.preDownloadNum == 0) return