Switch to Parallel.ForEach for list processing with MaxParallelism

(cherry picked from commit 0f93e04186f24abdb0cf0b3ba6a3505fda834e06)

src/NzbDrone.Core/ImportLists/FetchAndParseImportListService.cs

@@ -3,7 +3,6 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;
 using NLog;
-using NzbDrone.Common.TPL;
 using NzbDrone.Core.Parser.Model;
 
 namespace NzbDrone.Core.ImportLists
@@ -41,10 +40,7 @@ namespace NzbDrone.Core.ImportLists
 
             _logger.Debug("Available import lists {0}", importLists.Count);
 
-            var taskList = new List<Task>();
-            var taskFactory = new TaskFactory(TaskCreationOptions.LongRunning, TaskContinuationOptions.None);
-
-            foreach (var importList in importLists)
+            Parallel.ForEach(importLists, new ParallelOptions { MaxDegreeOfParallelism = 5 }, importList =>
             {
                 var importListLocal = importList;
                 var importListStatus = _importListStatusService.GetLastSyncListInfo(importListLocal.Definition.Id);
@@ -56,12 +52,10 @@ namespace NzbDrone.Core.ImportLists
                     if (DateTime.UtcNow < importListNextSync)
                     {
                         _logger.Trace("Skipping refresh of Import List {0} ({1}) due to minimum refresh interval. Next sync after {2}", importList.Name, importListLocal.Definition.Name, importListNextSync);
-                        continue;
+                        return;
                     }
                 }
 
-                var task = taskFactory.StartNew(() =>
-                     {
                 try
                 {
                     var importListReports = importListLocal.Fetch();
@@ -79,12 +73,7 @@ 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 = result.DistinctBy(r => new { r.Artist, r.Album }).ToList();
 
@@ -105,13 +94,8 @@ namespace NzbDrone.Core.ImportLists
                 return result;
             }
 
-            var taskList = new List<Task>();
-            var taskFactory = new TaskFactory(TaskCreationOptions.LongRunning, TaskContinuationOptions.None);
-
             var importListLocal = importList;
 
-            var task = taskFactory.StartNew(() =>
-            {
             try
             {
                 var importListReports = importListLocal.Fetch();
@@ -129,11 +113,6 @@ 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 = result.DistinctBy(r => new { r.Artist, r.Album }).ToList();