diff --git a/YaeBlog.Core/Models/BlogEssay.cs b/YaeBlog.Core/Models/BlogEssay.cs
index b06e887..218c461 100644
--- a/YaeBlog.Core/Models/BlogEssay.cs
+++ b/YaeBlog.Core/Models/BlogEssay.cs
@@ -4,6 +4,8 @@ public class BlogEssay
 {
     public required string Title { get; init; }
 
+    public required string FileName { get; init; }
+
     public required DateTime PublishTime { get; init; }
 
     public List<string> Tags { get; } = [];
diff --git a/YaeBlog.Core/Models/MarkdownMetadata.cs b/YaeBlog.Core/Models/MarkdownMetadata.cs
index f276b34..0296f19 100644
--- a/YaeBlog.Core/Models/MarkdownMetadata.cs
+++ b/YaeBlog.Core/Models/MarkdownMetadata.cs
@@ -6,5 +6,5 @@ public class MarkdownMetadata
 
     public DateTime? Date { get; set; }
 
-    public List<string> Tags { get; set; } = [];
+    public List<string>? Tags { get; set; }
 }
diff --git a/YaeBlog.Core/Services/RendererService.cs b/YaeBlog.Core/Services/RendererService.cs
index 611edfc..e842ebb 100644
--- a/YaeBlog.Core/Services/RendererService.cs
+++ b/YaeBlog.Core/Services/RendererService.cs
@@ -1,7 +1,9 @@
-using Markdig;
+using System.Diagnostics;
+using Markdig;
 using Microsoft.Extensions.Logging;
 using YaeBlog.Core.Exceptions;
 using YaeBlog.Core.Models;
+using YamlDotNet.Core;
 using YamlDotNet.Serialization;
 
 namespace YaeBlog.Core.Services;
@@ -12,33 +14,61 @@ public class RendererService(ILogger<RendererService> logger,
     IDeserializer yamlDeserializer,
     EssayContentService essayContentService)
 {
+    private readonly Stopwatch _stopwatch = new();
+
     public async Task RenderAsync()
     {
+        _stopwatch.Start();
+        logger.LogInformation("Render essays start.");
+
         List<BlogContent> contents = await essayScanService.ScanAsync();
 
-        Parallel.ForEach(contents, content =>
+        List<BlogEssay> essays = [];
+
+        await Task.Run(() =>
         {
-            MarkdownMetadata? metadata = TryParseMetadata(content);
+            foreach (BlogContent content in contents)
+            {
+                MarkdownMetadata? metadata = TryParseMetadata(content);
+                BlogEssay essay = new()
+                {
+                    Title = metadata?.Title ?? content.FileName,
+                    FileName = content.FileName,
+                    PublishTime = metadata?.Date ?? DateTime.Now,
+                    HtmlContent = content.FileContent
+                };
 
-            BlogEssay essay = new()
-            {
-                Title = metadata?.Title ?? content.FileName,
-                PublishTime = metadata?.Date ?? DateTime.Now,
-                HtmlContent = Markdown.ToHtml(content.FileContent, markdownPipeline)
-            };
-            if (metadata is not null)
-            {
-                essay.Tags.AddRange(essay.Tags);
+                if (metadata?.Tags is not null)
+                {
+                    essay.Tags.AddRange(metadata.Tags);
+                }
+                essays.Add(essay);
             }
+        });
 
-            if (!essayContentService.TryAdd(essay.Title, essay))
+        Parallel.ForEach(essays, essay =>
+        {
+
+            BlogEssay newEssay = new()
+            {
+                Title = essay.Title,
+                FileName = essay.FileName,
+                PublishTime = essay.PublishTime,
+                HtmlContent = Markdown.ToHtml(essay.HtmlContent, markdownPipeline)
+            };
+            newEssay.Tags.AddRange(essay.Tags);
+
+            if (!essayContentService.TryAdd(newEssay.FileName, newEssay))
             {
                 throw new BlogFileException(
-                    $"There are two essays with the same name: '{content.FileName}'.");
+                    $"There are two essays with the same name: '{newEssay.FileName}'.");
             }
-            logger.LogDebug("Render markdown file {}.", essay);
-            logger.LogDebug("{}", essay.HtmlContent);
+            logger.LogDebug("Render markdown file {}.", newEssay);
         });
+
+        _stopwatch.Stop();
+        logger.LogInformation("Render finished, consuming {} s.",
+            _stopwatch.Elapsed.ToString("s\\.fff"));
     }
 
     private MarkdownMetadata? TryParseMetadata(BlogContent content)
@@ -60,14 +90,23 @@ public class RendererService(ILogger<RendererService> logger,
         }
 
         string yamlContent = fileContent[..lastPos];
-        MarkdownMetadata metadata = yamlDeserializer.Deserialize<MarkdownMetadata>(yamlContent);
-        logger.LogDebug("Title: {}, Publish Date: {}.",
-            metadata.Title, metadata.Date);
-
         // 返回去掉元数据之后的文本
         lastPos += 3;
         content.FileContent = fileContent[lastPos..];
 
-        return null;
+        try
+        {
+            MarkdownMetadata metadata =
+                yamlDeserializer.Deserialize<MarkdownMetadata>(yamlContent);
+            logger.LogDebug("Title: {}, Publish Date: {}.",
+                metadata.Title, metadata.Date);
+
+            return metadata;
+        }
+        catch (YamlException e)
+        {
+            logger.LogWarning("Failed to parse '{}' metadata: {}", yamlContent, e);
+            return null;
+        }
     }
 }