Add GHCR Docker workflow for new-multithreaded-import; multithread scan changes

- Dockerfile.multithread: build from repo root for CI overlay on linuxserver/lidarr:nightly
- docker-ghcr-multithread.yml: push to ghcr.io on branch push + workflow_dispatch
- MediaFiles / RefreshArtist: fork behavior for multithreaded import

Made-with: Cursor

.github/workflows/docker-ghcr-multithread.yml

@@ -0,0 +1,43 @@
+# Build custom Lidarr overlay image and push to GHCR when this branch updates.
+name: Docker (multithread) → GHCR
+
+on:
+  push:
+    branches:
+      - new-multithreaded-import
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  packages: write
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository_owner }}/lidarr
+
+jobs:
+  build-push:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: Dockerfile.multithread
+          push: true
+          tags: |
+            ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:new-multithreaded-import
+            ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:git-${{ github.sha }}

Dockerfile.multithread

@@ -0,0 +1,19 @@
+# CI / context = repo root (lidarr-src). Local builds from parent folder use ../Dockerfile instead.
+FROM mcr.microsoft.com/dotnet/sdk:8.0 AS builder
+WORKDIR /src
+
+COPY . ./
+
+RUN dotnet publish src/NzbDrone.Console/Lidarr.Console.csproj \
+    -c Release \
+    -f net8.0 \
+    -r linux-musl-x64 \
+    --self-contained true \
+    -p:RunAnalyzers=false \
+    -p:EnforceCodeStyleInBuild=false \
+    -p:TreatWarningsAsErrors=false \
+    -o /out
+
+FROM ghcr.io/linuxserver/lidarr:nightly
+
+COPY --from=builder /out/ /app/lidarr/bin/

src/NzbDrone.Core/MediaFiles/DiskScanService.cs

@@ -5,6 +5,7 @@
 using System.IO.Abstractions;
 using System.Linq;
 using System.Text.RegularExpressions;
+using System.Threading.Tasks;
 using NLog;
 using NzbDrone.Common;
 using NzbDrone.Common.Disk;
@@ -84,23 +85,19 @@ public void Scan(List<string> folders = null, FilterFilesType filter = FilterFil
             }
 
             var mediaFileList = new List<IFileInfo>();
+            var mediaFileListLock = new object();
 
-            var musicFilesStopwatch = Stopwatch.StartNew();
-
+            // Validate folders first (early exit on error like original behaviour)
+            var foldersToScan = new List<string>();
             foreach (var folder in folders)
             {
-                // We could be scanning a root folder or a subset of a root folder.  If it's a subset,
-                // check if the root folder exists before cleaning.
                 var rootFolder = _rootFolderService.GetBestRootFolder(folder);
-
                 if (rootFolder == null)
                 {
                     _logger.Error("Not scanning {0}, it's not a subdirectory of a defined root folder", folder);
                     return;
                 }
-
                 var folderExists = _diskProvider.FolderExists(folder);
-
                 if (!folderExists)
                 {
                     if (!_diskProvider.FolderExists(rootFolder.Path))
@@ -110,7 +107,6 @@ public void Scan(List<string> folders = null, FilterFilesType filter = FilterFil
                         skippedArtists.ForEach(x => _eventAggregator.PublishEvent(new ArtistScanSkippedEvent(x, ArtistScanSkippedReason.RootFolderDoesNotExist)));
                         return;
                     }
-
                     if (_diskProvider.FolderEmpty(rootFolder.Path))
                     {
                         _logger.Warn("Artists' root folder ({0}) is empty.", rootFolder.Path);
@@ -119,28 +115,35 @@ public void Scan(List<string> folders = null, FilterFilesType filter = FilterFil
                         return;
                     }
                 }
-
                 if (!folderExists)
                 {
                     _logger.Debug("Specified scan folder ({0}) doesn't exist.", folder);
-
                     CleanMediaFiles(folder, new List<string>());
                     continue;
                 }
+                foldersToScan.Add(folder);
+            }
 
+            var musicFilesStopwatch = Stopwatch.StartNew();
+
+            Parallel.ForEach(foldersToScan, folder =>
+            {
                 _logger.ProgressInfo("Scanning {0}", folder);
 
-                var files = FilterFiles(folder, GetAudioFiles(folder));
+                var files = FilterFiles(folder, GetAudioFiles(folder)).ToList();
 
                 if (!files.Any())
                 {
                     _logger.Warn("Scan folder {0} is empty.", folder);
-                    continue;
+                    return;
                 }
 
                 CleanMediaFiles(folder, files.Select(x => x.FullName).ToList());
-                mediaFileList.AddRange(files);
-            }
+                lock (mediaFileListLock)
+                {
+                    mediaFileList.AddRange(files);
+                }
+            });
 
             var artists = _artistService.GetArtists(artistIds);
 

src/NzbDrone.Core/Music/Services/RefreshArtistService.cs

@@ -305,6 +305,13 @@ private void RescanArtists(List<Artist> artists, bool isNew, CommandTrigger trig
                 // badly organized / partly matched libraries
                 folders = artists.Select(x => x.Path).ToList();
             }
+            else if (trigger == CommandTrigger.Manual && artists.Any())
+            {
+                // Manual refresh of specific artist(s): only scan those artists' folders,
+                // never the entire library (avoids 60k+ file scan when refreshing e.g. Various Artists).
+                folders = artists.Select(x => x.Path).ToList();
+                _logger.Trace("Manual refresh: rescanning only {0} artist folder(s)", folders.Count);
+            }
             else if (rescanAfterRefresh == RescanAfterRefreshType.Never)
             {
                 _logger.Trace("Skipping rescan. Reason: never rescan after refresh");