Async Sink Flush Issue with Exception Rethrow

[willbush]

Description

Something about how Serilog or one of the sinks handles the rethrow (in the catch block) causes Log.CloseAndFlush() to not flush.

Not sure if I should report this as an issue here or the one of the sinks.

Reproduction

using Serilog;

Log.Logger = new LoggerConfiguration()
    .WriteTo.Async(x => x.Console())
    .CreateLogger();

try
{
    Serilog.Debugging.SelfLog.Enable(Console.WriteLine);
    Log.Information("Hello!");
    throw new Exception("hi");
}
catch (Exception ex)
{
    Log.Fatal(ex, "Error");
    throw;
}
finally
{
    Log.CloseAndFlush();
}

test-serilog.csproj:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net8.0</TargetFramework>
    <RootNamespace>test_serilog</RootNamespace>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Serilog" Version="3.1.1" />
    <PackageReference Include="Serilog.Sinks.Async" Version="1.5.0" />
    <PackageReference Include="Serilog.Sinks.Console" Version="5.0.1" />
    <PackageReference Include="Serilog.Sinks.File" Version="5.0.0" />
  </ItemGroup>

</Project>

output:

test-serilog on  main [?] via .NET v8.0.201 🎯 net8.0
❯ dotnet run
Unhandled exception. [System.Exception: hi
   at Program.<Main>$(String[] args) in /home/will/code/test-serilog/Program.cs:line 11

Change the following:

@@ -17,5 +17,5 @@ catch (Exception ex)
 }
 finally
 {
-   Log.CloseAndFlush();
+   await Log.CloseAndFlushAsync();
 }

output becomes:

test-serilog on  main [?] via .NET v8.0.201 🎯 net8.0
❯ dotnet run
[16:44:33 INF] Hello!
[16:44:33 FTL] Error
System.Exception: hi
   at Program.<Main>$(String[] args) in /home/will/code/test-serilog/Program.cs:line 11
Unhandled exception. System.Exception: hi
   at Program.<Main>$(String[] args) in /home/will/code/test-serilog/Program.cs:line 11
   at Program.<Main>$(String[] args) in /home/will/code/test-serilog/Program.cs:line 21
   at Program.<Main>(String[] args)

Change it back to using Log.CloseAndFlush(); and remove the throw;:

@@ -13,7 +13,6 @@ try
 catch (Exception ex)
 {
    Log.Fatal(ex, "Error");
-   throw;
 }
 finally
 {

And it also works.

❯ dotnet run
[16:45:45 INF] Hello!
[16:45:45 FTL] Error
System.Exception: hi
   at Program.<Main>$(String[] args) in /home/will/code/test-serilog/Program.cs:line 11

Only seems to be an issue with Async sink. I've only tested Async Console.

Expected behavior

I expected Log.CloseAndFlush() to flush the log in a finally block despite a rethrown exception.

Relevant package, tooling and runtime versions

Package versions are in the csproj file above.

❯ dotnet --info
.NET SDK:
 Version:           8.0.201
 Commit:            4c2d78f037
 Workload version:  8.0.200-manifests.3097af8b

Runtime Environment:
 OS Name:     nixos
 OS Version:  24.05
 OS Platform: Linux
 RID:         linux-x64
 Base Path:   /nix/store/dh9gg36zckspv5isph8lwfw50fc2bbsc-dotnet-sdk-8.0.201/sdk/8.0.201/

.NET workloads installed:
There are no installed workloads to display.

Host:
  Version:      8.0.2
  Architecture: x64
  Commit:       1381d5ebd2

.NET SDKs installed:
  7.0.406 [/nix/store/rck91567galfwgah5302gz7l6il7gy9v-dotnet-core-combined/sdk]
  8.0.201 [/nix/store/rck91567galfwgah5302gz7l6il7gy9v-dotnet-core-combined/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 7.0.16 [/nix/store/rck91567galfwgah5302gz7l6il7gy9v-dotnet-core-combined/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 8.0.2 [/nix/store/rck91567galfwgah5302gz7l6il7gy9v-dotnet-core-combined/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 7.0.16 [/nix/store/rck91567galfwgah5302gz7l6il7gy9v-dotnet-core-combined/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 8.0.2 [/nix/store/rck91567galfwgah5302gz7l6il7gy9v-dotnet-core-combined/shared/Microsoft.NETCore.App]

Other architectures found:
  None

Environment variables:
  DOTNET_ROOT       [/nix/store/rck91567galfwgah5302gz7l6il7gy9v-dotnet-core-combined]

global.json file:
  Not found

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  https://aka.ms/dotnet/info

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  https://aka.ms/dotnet/download

Additional context