Revert "Switch to Parallel.ForEach for list processing with MaxParallelism"

This reverts commit 0f93e04186.

src/NzbDrone.Core/ImportLists/FetchAndParseImportListService.cs

@@ -4,6 +4,7 @@ using System.Linq;
 using System.Threading.Tasks;
 using NLog;
 using NzbDrone.Common.Instrumentation.Extensions;
+using NzbDrone.Common.TPL;
 using NzbDrone.Core.ImportLists.ImportListMovies;
 using NzbDrone.Core.MetadataSource;
 using NzbDrone.Core.Movies;
@@ -22,6 +23,7 @@ namespace NzbDrone.Core.ImportLists
         private readonly IImportListStatusService _importListStatusService;
         private readonly IImportListMovieService _listMovieService;
         private readonly ISearchForNewMovie _movieSearch;
+        private readonly IProvideMovieInfo _movieInfoService;
         private readonly IMovieMetadataService _movieMetadataService;
         private readonly Logger _logger;
 
@@ -29,6 +31,7 @@ namespace NzbDrone.Core.ImportLists
                                               IImportListStatusService importListStatusService,
                                               IImportListMovieService listMovieService,
                                               ISearchForNewMovie movieSearch,
+                                              IProvideMovieInfo movieInfoService,
                                               IMovieMetadataService movieMetadataService,
                                               Logger logger)
         {
@@ -36,6 +39,7 @@ namespace NzbDrone.Core.ImportLists
             _importListStatusService = importListStatusService;
             _listMovieService = listMovieService;
             _movieSearch = movieSearch;
+            _movieInfoService = movieInfoService;
             _movieMetadataService = movieMetadataService;
             _logger = logger;
         }
@@ -54,7 +58,10 @@ namespace NzbDrone.Core.ImportLists
 
             _logger.Debug("Available import lists {0}", importLists.Count);
 
-            Parallel.ForEach(importLists, new ParallelOptions { MaxDegreeOfParallelism = 5 }, importList =>
+            var taskList = new List<Task>();
+            var taskFactory = new TaskFactory(TaskCreationOptions.LongRunning, TaskContinuationOptions.None);
+
+            foreach (var importList in importLists)
             {
                 var importListLocal = importList;
                 var importListStatus = _importListStatusService.GetLastSyncListInfo(importListLocal.Definition.Id);
@@ -67,7 +74,7 @@ namespace NzbDrone.Core.ImportLists
                     {
                         _logger.Trace("Skipping refresh of Import List {0} ({1}) due to minimum refresh interval. Next Sync after {2}", importList.Name, importListLocal.Definition.Name, importListNextSync);
 
-                        return;
+                        continue;
                     }
                 }
 
@@ -79,9 +86,11 @@ namespace NzbDrone.Core.ImportLists
                 {
                     _logger.Debug("Temporarily ignoring Import List {0} ({1}) till {2} due to recent failures.", importList.Name, importListLocal.Definition.Name, blockedListStatus.DisabledTill.Value.ToLocalTime());
                     result.AnyFailure |= true; // Ensure we don't clean if a list is down
-                    return;
+                    continue;
                 }
 
+                var task = taskFactory.StartNew(() =>
+                {
                     try
                     {
                         var importListReports = importListLocal.Fetch();
@@ -113,7 +122,12 @@ namespace NzbDrone.Core.ImportLists
                     {
                         _logger.Error(e, "Error during Import List Sync of {0} ({1})", importList.Name, importListLocal.Definition.Name);
                     }
-            });
+                }).LogExceptions();
+
+                taskList.Add(task);
+            }
+
+            Task.WaitAll(taskList.ToArray());
 
             result.Movies = result.Movies.DistinctBy(r => new { r.TmdbId, r.ImdbId, r.Title }).ToList();