Fix thread starvation caused by not yielding or using an inappropriate thread pool (#2955)

app/src/main/java/eu/kanade/tachiyomi/data/download/DownloadManager.kt

@@ -104,10 +104,10 @@ class DownloadManager(
         return queueState.value.find { it.chapter.id == chapterId }
     }
 
-    fun startDownloadNow(chapterId: Long) {
+    suspend fun startDownloadNow(chapterId: Long) {
         val existingDownload = getQueuedDownloadOrNull(chapterId)
         // If not in queue try to start a new download
-        val toAdd = existingDownload ?: runBlocking { Download.fromChapterId(chapterId) } ?: return
+        val toAdd = existingDownload ?: Download.fromChapterId(chapterId) ?: return
         queueState.value.toMutableList().apply {
             existingDownload?.let { remove(it) }
             add(0, toAdd)

app/src/main/java/eu/kanade/tachiyomi/data/download/DownloadStore.kt

@@ -90,7 +90,7 @@ class DownloadStore(
     /**
      * Returns the list of downloads to restore. It should be called in a background thread.
      */
-    fun restore(): List<Download> {
+    suspend fun restore(): List<Download> {
         val objs = preferences.all
             .mapNotNull { it.value as? String }
             .mapNotNull { deserialize(it) }
@@ -101,10 +101,10 @@ class DownloadStore(
             val cachedManga = mutableMapOf<Long, Manga?>()
             for ((mangaId, chapterId) in objs) {
                 val manga = cachedManga.getOrPut(mangaId) {
-                    runBlocking { getManga.await(mangaId) }
+                    getManga.await(mangaId)
                 } ?: continue
                 val source = sourceManager.get(manga.source) as? HttpSource ?: continue
-                val chapter = runBlocking { getChapter.await(chapterId) } ?: continue
+                val chapter = getChapter.await(chapterId) ?: continue
                 downloads.add(Download(source, manga, chapter))
             }
         }

app/src/main/java/eu/kanade/tachiyomi/data/download/Downloader.kt

@@ -111,9 +111,9 @@ class Downloader(
     var isPaused: Boolean = false
 
     init {
-        launchNow {
-            val chapters = async { store.restore() }
-            addAllToQueue(chapters.await())
+        scope.launch {
+            val chapters = store.restore()
+            addAllToQueue(chapters)
         }
     }