#5236 - Added options to set (and set default as) the log file is closed after each log event

src/Umbraco.Core/Logging/Serilog/LoggerConfigExtensions.cs

@@ -13,6 +13,7 @@ namespace Umbraco.Core.Logging.Serilog
 {
     public static class LoggerConfigExtensions
     {
+        private const string AppDomainId = "AppDomainId";
         /// <summary>
         /// This configures Serilog with some defaults
         /// Such as adding ProcessID, Thread, AppDomain etc
@@ -32,7 +33,7 @@ namespace Umbraco.Core.Logging.Serilog
                 .Enrich.WithProcessId()
                 .Enrich.WithProcessName()
                 .Enrich.WithThreadId()
-                .Enrich.WithProperty("AppDomainId", AppDomain.CurrentDomain.Id)
+                .Enrich.WithProperty(AppDomainId, AppDomain.CurrentDomain.Id)
                 .Enrich.WithProperty("AppDomainAppId", HttpRuntime.AppDomainAppId.ReplaceNonAlphanumericChars(string.Empty))
                 .Enrich.WithProperty("MachineName", Environment.MachineName)
                 .Enrich.With<Log4NetLevelMapperEnricher>()
@@ -81,7 +82,8 @@ namespace Umbraco.Core.Logging.Serilog
             Encoding encoding = null,
             bool async = false,
             bool asyncBlockWhenFull = false,
-            int asyncBufferSize = 10000)
+            int asyncBufferSize = 10000,
+            bool asyncKeepFileOpen = true)
         {
             LoggerConfiguration GetFileSink(LoggerSinkConfiguration c)
             {
@@ -100,17 +102,36 @@ namespace Umbraco.Core.Logging.Serilog
                     encoding);
             }
 
-            if ( async )
+            if (!async && !asyncKeepFileOpen)
             {
+                throw new InvalidOperationException($"{nameof(asyncKeepFileOpen)} cannot be changed if async is false.");
+            }
+            if (!async && rollOnFileSizeLimit)
+            {
+                throw new InvalidOperationException($"{nameof(rollOnFileSizeLimit)} cannot be changed if async is false.");
+            }
 
-                return configuration.Async(c => GetFileSink(c), blockWhenFull: asyncBlockWhenFull, bufferSize: asyncBufferSize);
-            }
-            else
+            if (async)
             {
-                return GetFileSink(configuration);
+                Action<LoggerSinkConfiguration> configure;
+                if (asyncKeepFileOpen)
+                {
+                    configure = a => GetFileSink(a);
+                }
+                else
+                {
+                    // This is a way to force the file to be closed after each log event. Read more https://github.com/serilog/serilog-sinks-file/issues/99#issuecomment-488612711
+                    // We basically map all log events with a AppDomainId property (all events) into a file sink and forces the sink to be closed, due to the sinkMapCountLimit = 0.
+                    configure = a => a.Map(AppDomainId, (name,c) => GetFileSink(c), sinkMapCountLimit:0);
+                }
+
+                return configuration.Async(configure, blockWhenFull: asyncBlockWhenFull, bufferSize: asyncBufferSize);
+
             }
+            return GetFileSink(configuration);
         }
 
+
         /// <summary>
         /// Outputs a CLEF format JSON log at /App_Data/Logs/
         /// </summary>

src/Umbraco.Core/Umbraco.Core.csproj

@@ -55,6 +55,12 @@
   </ItemGroup>
   <ItemGroup>
     <!-- note: NuGet deals with transitive references now -->
+    <PackageReference Include="Serilog.Sinks.Async">
+      <Version>1.3.0</Version>
+    </PackageReference>
+    <PackageReference Include="Serilog.Sinks.Map">
+      <Version>1.0.0</Version>
+    </PackageReference>
     <PackageReference Include="Umbraco.Code">
       <Version>1.0.5</Version>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>

src/Umbraco.Web.UI/config/serilog.Release.config

@@ -20,11 +20,12 @@
         <add key="serilog:using:File" value="Umbraco.Core" />
         <add key="serilog:write-to:File.formatter" value="Serilog.Formatting.Compact.CompactJsonFormatter, Serilog.Formatting.Compact" />
         <add key="serilog:write-to:File.path" value="%BASEDIR%\App_Data\Logs\UmbracoTraceLog.%MACHINENAME%..json" />
-        <add key="serilog:write-to:File.shared" value="true" />
+        <add key="serilog:write-to:File.shared" value="false" />
         <add key="serilog:write-to:File.restrictedToMinimumLevel" value="Debug" />
         <add key="serilog:write-to:File.retainedFileCountLimit" value="" /> <!-- Number of log files to keep (or remove value to keep all files) -->
         <add key="serilog:write-to:File.rollingInterval" value="Day" /> <!-- Create a new log file every Minute/Hour/Day/Month/Year/infinite -->
         <add key="serilog:write-to:File.async" value="true" />
+        <add key="serilog:write-to:File.asyncKeepFileOpen" value="false" />
 
         <!-- Optional TXT log file -->
         <!--<add key="serilog:using:File" value="Serilog.Sinks.File" /> -->