diff --git a/app/src/main/java/io/legado/app/help/book/BookHelp.kt b/app/src/main/java/io/legado/app/help/book/BookHelp.kt
index f70d93724..acbf32566 100644
--- a/app/src/main/java/io/legado/app/help/book/BookHelp.kt
+++ b/app/src/main/java/io/legado/app/help/book/BookHelp.kt
@@ -10,6 +10,7 @@ import io.legado.app.data.appDb
 import io.legado.app.data.entities.Book
 import io.legado.app.data.entities.BookChapter
 import io.legado.app.data.entities.BookSource
+import io.legado.app.help.config.AppConfig
 import io.legado.app.model.analyzeRule.AnalyzeUrl
 import io.legado.app.model.localBook.LocalBook
 import io.legado.app.utils.ArchiveUtils
@@ -24,12 +25,13 @@ import io.legado.app.utils.exists
 import io.legado.app.utils.externalFiles
 import io.legado.app.utils.getFile
 import io.legado.app.utils.isContentScheme
+import io.legado.app.utils.onEachParallel
 import io.legado.app.utils.postEvent
-import kotlinx.coroutines.Deferred
 import kotlinx.coroutines.Dispatchers.IO
-import kotlinx.coroutines.async
 import kotlinx.coroutines.coroutineScope
 import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.flow.flow
 import kotlinx.coroutines.withContext
 import org.apache.commons.text.similarity.JaccardSimilarity
 import splitties.init.appCtx
@@ -151,19 +153,16 @@ object BookHelp {
         bookChapter: BookChapter,
         content: String
     ) = coroutineScope {
-        val awaitList = arrayListOf<Deferred<Unit>>()
-        val matcher = AppPattern.imgPattern.matcher(content)
-        while (matcher.find()) {
-            matcher.group(1)?.let { src ->
+        flow {
+            val matcher = AppPattern.imgPattern.matcher(content)
+            while (matcher.find()) {
+                val src = matcher.group(1) ?: continue
                 val mSrc = NetworkUtils.getAbsoluteURL(bookChapter.url, src)
-                awaitList.add(async {
-                    saveImage(bookSource, book, mSrc, bookChapter)
-                })
+                emit(mSrc)
             }
-        }
-        awaitList.forEach {
-            it.await()
-        }
+        }.onEachParallel(AppConfig.threadCount) { mSrc ->
+            saveImage(bookSource, book, mSrc, bookChapter)
+        }.collect()
     }
 
     suspend fun saveImage(
diff --git a/app/src/main/java/io/legado/app/model/webBook/BookChapterList.kt b/app/src/main/java/io/legado/app/model/webBook/BookChapterList.kt
index fb7ccfdb4..240b010f7 100644
--- a/app/src/main/java/io/legado/app/model/webBook/BookChapterList.kt
+++ b/app/src/main/java/io/legado/app/model/webBook/BookChapterList.kt
@@ -11,13 +11,15 @@ import io.legado.app.data.entities.rule.TocRule
 import io.legado.app.exception.NoStackTraceException
 import io.legado.app.exception.TocEmptyException
 import io.legado.app.help.book.ContentProcessor
+import io.legado.app.help.config.AppConfig
 import io.legado.app.model.Debug
 import io.legado.app.model.analyzeRule.AnalyzeRule
 import io.legado.app.model.analyzeRule.AnalyzeUrl
 import io.legado.app.utils.isTrue
+import io.legado.app.utils.mapAsync
 import kotlinx.coroutines.Dispatchers.IO
-import kotlinx.coroutines.async
 import kotlinx.coroutines.ensureActive
+import kotlinx.coroutines.flow.flow
 import kotlinx.coroutines.withContext
 import splitties.init.appCtx
 import kotlin.coroutines.coroutineContext
@@ -87,23 +89,23 @@ object BookChapterList {
                     "◇并发解析目录,总页数:${chapterData.second.size}"
                 )
                 withContext(IO) {
-                    val asyncArray = Array(chapterData.second.size) {
-                        async(IO) {
-                            val urlStr = chapterData.second[it]
-                            val res = AnalyzeUrl(
-                                mUrl = urlStr,
-                                source = bookSource,
-                                ruleData = book,
-                                headerMapF = bookSource.getHeaderMap()
-                            ).getStrResponseAwait() //控制并发访问
-                            analyzeChapterList(
-                                book, urlStr, res.url,
-                                res.body!!, tocRule, listRule, bookSource, false
-                            ).first
+                    flow {
+                        for (urlStr in chapterData.second) {
+                            emit(urlStr)
                         }
-                    }
-                    asyncArray.forEach { coroutine ->
-                        chapterList.addAll(coroutine.await())
+                    }.mapAsync(AppConfig.threadCount) { urlStr ->
+                        val res = AnalyzeUrl(
+                            mUrl = urlStr,
+                            source = bookSource,
+                            ruleData = book,
+                            headerMapF = bookSource.getHeaderMap()
+                        ).getStrResponseAwait() //控制并发访问
+                        analyzeChapterList(
+                            book, urlStr, res.url,
+                            res.body!!, tocRule, listRule, bookSource, false
+                        ).first
+                    }.collect {
+                        chapterList.addAll(it)
                     }
                 }
             }
@@ -142,7 +144,8 @@ object BookChapterList {
             }
         }
         val replaceRules = ContentProcessor.get(book.name, book.origin).getTitleReplaceRules()
-        book.latestChapterTitle = list.last().getDisplayTitle(replaceRules, book.getUseReplaceRule())
+        book.latestChapterTitle =
+            list.last().getDisplayTitle(replaceRules, book.getUseReplaceRule())
         book.durChapterTitle = list.getOrElse(book.durChapterIndex) { list.last() }
             .getDisplayTitle(replaceRules, book.getUseReplaceRule())
         if (book.totalChapterNum < list.size) {
diff --git a/app/src/main/java/io/legado/app/service/ExportBookService.kt b/app/src/main/java/io/legado/app/service/ExportBookService.kt
index 8ebab110c..6bb1cc0ca 100644
--- a/app/src/main/java/io/legado/app/service/ExportBookService.kt
+++ b/app/src/main/java/io/legado/app/service/ExportBookService.kt
@@ -42,6 +42,8 @@ import io.legado.app.utils.activityPendingIntent
 import io.legado.app.utils.cnCompare
 import io.legado.app.utils.createFolderIfNotExist
 import io.legado.app.utils.isContentScheme
+import io.legado.app.utils.mapAsync
+import io.legado.app.utils.mapAsyncIndexed
 import io.legado.app.utils.outputStream
 import io.legado.app.utils.postEvent
 import io.legado.app.utils.readBytes
@@ -49,20 +51,14 @@ import io.legado.app.utils.readText
 import io.legado.app.utils.servicePendingIntent
 import io.legado.app.utils.toastOnUi
 import io.legado.app.utils.writeBytes
-import kotlinx.coroutines.CoroutineStart
 import kotlinx.coroutines.Deferred
-import kotlinx.coroutines.Dispatchers.Default
 import kotlinx.coroutines.Dispatchers.IO
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.async
 import kotlinx.coroutines.coroutineScope
 import kotlinx.coroutines.ensureActive
-import kotlinx.coroutines.flow.buffer
 import kotlinx.coroutines.flow.collectIndexed
 import kotlinx.coroutines.flow.flow
-import kotlinx.coroutines.flow.map
-import kotlinx.coroutines.flow.onEach
-import kotlinx.coroutines.flow.withIndex
 import kotlinx.coroutines.launch
 import me.ag2s.epublib.domain.Author
 import me.ag2s.epublib.domain.Date
@@ -327,23 +323,19 @@ class ExportBookService : BaseService() {
         val threads = if (AppConfig.parallelExportBook) {
             AppConst.MAX_THREAD
         } else {
-            0
+            1
         }
         flow {
             appDb.bookChapterDao.getChapterList(book.bookUrl).forEach { chapter ->
-                val task = async(Default, start = CoroutineStart.LAZY) {
-                    getExportData(book, chapter, contentProcessor, useReplace)
-                }
-                emit(task)
-            }
-        }.onEach { it.start() }
-            .buffer(threads)
-            .map { it.await() }
-            .collectIndexed { index, result ->
-                postEvent(EventBus.EXPORT_BOOK, book.bookUrl)
-                exportProgress[book.bookUrl] = index
-                append.invoke(result.first, result.second)
+                emit(chapter)
             }
+        }.mapAsync(threads) { chapter ->
+            getExportData(book, chapter, contentProcessor, useReplace)
+        }.collectIndexed { index, result ->
+            postEvent(EventBus.EXPORT_BOOK, book.bookUrl)
+            exportProgress[book.bookUrl] = index
+            append.invoke(result.first, result.second)
+        }
 
     }
 
@@ -641,56 +633,52 @@ class ExportBookService : BaseService() {
         val threads = if (AppConfig.parallelExportBook) {
             AppConst.MAX_THREAD
         } else {
-            0
+            1
         }
         flow {
-            appDb.bookChapterDao.getChapterList(book.bookUrl).forEachIndexed { index, chapter ->
-                val task = async(Default, start = CoroutineStart.LAZY) {
-                    val content = BookHelp.getContent(book, chapter)
-                    val (contentFix, resources) = fixPic(
-                        book,
-                        content ?: if (chapter.isVolume) "" else "null",
-                        chapter
-                    )
-                    // 不导出vip标识
-                    chapter.isVip = false
-                    val content1 = contentProcessor
-                        .getContent(
-                            book,
-                            chapter,
-                            contentFix,
-                            includeTitle = false,
-                            useReplace = useReplace,
-                            chineseConvert = false,
-                            reSegment = false
-                        ).toString()
-                    val title = chapter.run {
-                        // 不导出vip标识
-                        isVip = false
-                        getDisplayTitle(
-                            contentProcessor.getTitleReplaceRules(),
-                            useReplace = useReplace
-                        )
-                    }
-                    val chapterResource = ResourceUtil.createChapterResource(
-                        title.replace("\uD83D\uDD12", ""),
-                        content1,
-                        contentModel,
-                        "Text/chapter_${index}.html"
-                    )
-                    ExportChapter(title, chapterResource, resources)
-                }
-                emit(task)
+            appDb.bookChapterDao.getChapterList(book.bookUrl).forEach { chapter ->
+                emit(chapter)
             }
-        }.onEach { it.start() }
-            .buffer(threads)
-            .map { it.await() }
-            .collectIndexed { index, exportChapter ->
-                postEvent(EventBus.EXPORT_BOOK, book.bookUrl)
-                exportProgress[book.bookUrl] = index
-                epubBook.resources.addAll(exportChapter.resources)
-                epubBook.addSection(exportChapter.title, exportChapter.chapterResource)
+        }.mapAsyncIndexed(threads) { index, chapter ->
+            val content = BookHelp.getContent(book, chapter)
+            val (contentFix, resources) = fixPic(
+                book,
+                content ?: if (chapter.isVolume) "" else "null",
+                chapter
+            )
+            // 不导出vip标识
+            chapter.isVip = false
+            val content1 = contentProcessor
+                .getContent(
+                    book,
+                    chapter,
+                    contentFix,
+                    includeTitle = false,
+                    useReplace = useReplace,
+                    chineseConvert = false,
+                    reSegment = false
+                ).toString()
+            val title = chapter.run {
+                // 不导出vip标识
+                isVip = false
+                getDisplayTitle(
+                    contentProcessor.getTitleReplaceRules(),
+                    useReplace = useReplace
+                )
             }
+            val chapterResource = ResourceUtil.createChapterResource(
+                title.replace("\uD83D\uDD12", ""),
+                content1,
+                contentModel,
+                "Text/chapter_${index}.html"
+            )
+            ExportChapter(title, chapterResource, resources)
+        }.collectIndexed { index, exportChapter ->
+            postEvent(EventBus.EXPORT_BOOK, book.bookUrl)
+            exportProgress[book.bookUrl] = index
+            epubBook.resources.addAll(exportChapter.resources)
+            epubBook.addSection(exportChapter.title, exportChapter.chapterResource)
+        }
     }
 
     data class ExportChapter(
diff --git a/app/src/main/java/io/legado/app/utils/FlowExtensions.kt b/app/src/main/java/io/legado/app/utils/FlowExtensions.kt
index b30152866..5a173252e 100644
--- a/app/src/main/java/io/legado/app/utils/FlowExtensions.kt
+++ b/app/src/main/java/io/legado/app/utils/FlowExtensions.kt
@@ -1,17 +1,22 @@
 package io.legado.app.utils
 
 import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.async
 import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.channelFlow
 import kotlinx.coroutines.flow.filterNotNull
 import kotlinx.coroutines.flow.flatMapMerge
 import kotlinx.coroutines.flow.flow
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.onEach
+import kotlinx.coroutines.sync.Semaphore
 
 @OptIn(ExperimentalCoroutinesApi::class)
 inline fun <T> Flow<T>.onEachParallel(
     concurrency: Int,
     crossinline action: suspend (T) -> Unit
 ): Flow<T> = flatMapMerge(concurrency) { value ->
-    return@flatMapMerge flow {
+    flow {
         action(value)
         emit(value)
     }
@@ -37,3 +42,98 @@ inline fun <T> Flow<T>.onEachIndexed(
         emit(value)
     }
 }
+
+inline fun <T, R> Flow<T>.mapIndexed(
+    crossinline action: suspend (index: Int, T) -> R,
+): Flow<R> = flow {
+    var index = 0
+    collect { value ->
+        emit(action(index++, value))
+    }
+}
+
+inline fun <T, R> Flow<T>.mapAsync(
+    concurrency: Int,
+    crossinline transform: suspend (T) -> R
+): Flow<R> = if (concurrency == 1) {
+    map { transform(it) }
+} else {
+    Semaphore(concurrency).let { semaphore ->
+        channelFlow {
+            collect {
+                semaphore.acquire()
+                send(async { transform(it) })
+            }
+        }.map {
+            it.await()
+        }.onEach { semaphore.release() }
+    }
+}
+
+inline fun <T, R> Flow<T>.mapAsyncIndexed(
+    concurrency: Int,
+    crossinline transform: suspend (index: Int, T) -> R
+): Flow<R> = if (concurrency == 1) {
+    mapIndexed { index, value ->
+        transform(index, value)
+    }
+} else {
+    Semaphore(concurrency).let { semaphore ->
+        channelFlow {
+            var index = 0
+            collect {
+                semaphore.acquire()
+                val i = index++
+                send(async { transform(i, it) })
+            }
+        }.map {
+            it.await()
+        }.onEach { semaphore.release() }
+    }
+}
+
+inline fun <T> Flow<T>.onEachAsync(
+    concurrency: Int,
+    crossinline action: suspend (T) -> Unit
+): Flow<T> = if (concurrency == 1) {
+    onEach { action(it) }
+} else {
+    Semaphore(concurrency).let { semaphore ->
+        channelFlow {
+            collect {
+                semaphore.acquire()
+                send(async {
+                    action(it)
+                    it
+                })
+            }
+        }.map {
+            it.await()
+        }.onEach { semaphore.release() }
+    }
+}
+
+inline fun <T> Flow<T>.onEachAsyncIndexed(
+    concurrency: Int,
+    crossinline action: suspend (index: Int, T) -> Unit
+): Flow<T> = if (concurrency == 1) {
+    onEachIndexed { index, value ->
+        action(index, value)
+    }
+} else {
+    Semaphore(concurrency).let { semaphore ->
+        channelFlow {
+            var index = 0
+            collect {
+                semaphore.acquire()
+                val i = index++
+                send(async {
+                    action(i, it)
+                    it
+                })
+            }
+        }.map {
+            it.await()
+        }.onEach { semaphore.release() }
+    }
+}