This is the fifth in a series of posts covering measuring a .Net Core application. If you want to try follow the code then you can have a look at this repo: Blog-Diagnostics.
This is the plan for the series. I will update this with links as it evolves.
- Setting up local diagnostics tools
- Using dotnet-counters
- dotnet-counters with a custom provider
- Using dotnet-gcdump to investigate memory leaks
- Creating a dump file when a ASP.NET Core application crashes
A nice out of the box feature of ASP.NET Core, is that there is a built in way to automatically create a memory dump when the application crashes.
All you have to do is set a few environment variables and it will generate automatically. The full list of available options is available here.
Just to show it working I will just set this Environment variable.
COMPlus_DbgEnableMiniDump=1
I will then update the application to throw an exception in the startup ConfigureServices method.
public void ConfigureServices(IServiceCollection services)
{
services.AddControllers();
throw new Exception("Something bad happened");
}
The application crashes as it starts as expected. Now its time to look at the dump file.
This returns the file /tmp/coredump.34121
which was generated. I can then use the dotnet dump tool to run SOS commands on the dump file.
dotnet dump analyze /tmp/coredump.34121
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Since I’m looking for the reason that the application crashed, I can just use the print exception (pe) command to see what the last exception was.
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As you can see, this shows the full stack trace of the exception thrown in the Startup class.