aspnet core 3.1 linux ThreadPool.SetMinThreads is not work

[gaojiandonggg]

Describe the bug

A clear and concise description of what the bug is.

To Reproduce

hello
aspnet core 3.1
int processorCount = Environment.ProcessorCount;
ThreadPool.SetMinThreads(processorCount * 5, processorCount * 100);
run in docker is not working by linux ,
but can working in windows ,why?
who can help me, thinks

[analogrelay]

I don't think this is specific to ASP.NET Core. I'm going to transfer this to dotnet/runtime and see if someone there can help.

[stephentoub]

is not working by linux

How does that manifest?

What is the value of processorCount?

What is the return value of SetMinThreads?

[gaojiandonggg]

For example, if the system has 4 cores, then processorCount should be 4. In Windows and Linux systems, I can normally get the value from a container of Linux docker run, but if I start the instance with k8s, it will display as follows:

ThreadPool.ThreadCount: 16, Minimum work threads: 16, Minimum completion port threads: 16)

It might have something to do with the k8s Settings

[stephentoub]

Thanks, but I'm trying to understand what you mean by "is not working". What is the symptom that you're reporting? Is SetMinThreads returning false? Are you querying GetMinThreads after you call SetMinThreads and it's not reporting the values you passed in?

[jeffschwMSFT]

cc @kouvel

[dktue]

We're having the same issue: It shows exactly like you told, @stephentoub .

[maxtyutmanov]

Same trouble on .net core 2.2.8 in docker under linux, using microsoft/dotnet:2.2-aspnetcore-runtime as base image.
The code snippet that we use for thread pool configuration:

private static void ConfigureThreadPool(IConfiguration configuration)
{
	ThreadPool.GetMinThreads(out var currentMinWorkerThreads, out var currentMinIoThreads);

	System.Console.WriteLine(
		"Current thread pool config: min worker threads - {0}, min IO threads - {1}", 
		currentMinWorkerThreads, currentMinIoThreads);

	var newMinWorkerThreads = configuration.GetValue<int?>("MinThreadPoolWorkerThreads") ?? currentMinWorkerThreads;

	System.Console.WriteLine("Reconfiguring thread pool: min worker threads - {0}", newMinWorkerThreads);

	var success = ThreadPool.SetMinThreads(newMinWorkerThreads, currentMinIoThreads);
	if (success)
	{
		ThreadPool.GetMinThreads(out currentMinWorkerThreads, out currentMinIoThreads);
		System.Console.WriteLine(
			"Successfully reconfigured thread pool: min worker threads - {0}, min IO threads - {1}",
			currentMinWorkerThreads, currentMinIoThreads);
	}
	else
	{
		System.Console.WriteLine("Could not reconfigure thread pool");
	}
}

and this is the output I am getting:

Current thread pool config: min worker threads - 80, min IO threads - 2
Reconfiguring thread pool: min worker threads - 128
Successfully reconfigured thread pool: min worker threads - 80, min IO threads - 2

The same code works fine when run locally on my Windows 10 machine.
I also tried setting System.Threading.ThreadPool.MinThreads in runtimeconfig.template.json, no success.
Any idea what could cause such behavior?

[kouvel]

It sounds like it might already be configured somehow. Could be through System.Threading.ThreadPool.MinThreads, can you check in <app>.runtimeconfig.json in the build output folder? It may also be overridden using an environment variable COMPlus_ThreadPool_ForceMinWorkerThreads=0x50 using a hex value. Those settings would override the value set by ThreadPool.SetMinThreads despite it returning true.

[maxtyutmanov]

@kouvel COMPlus_ThreadPool_ForceMinWorkerThreads=0x50 was exactly the reason, thank you!
The behavior of SetMinThreads looks non-intuitive to me though: it reported success, but did not change the settings.

[kouvel]

Yea looks like historical behavior, perhaps it was intended that returning true means that the values provided are valid rather than that the values were changed. Probably could fix.