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Document new threading settings #47575

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Document new threading settings
MichalStrehovsky Jul 25, 2025
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Update threading.md
MichalStrehovsky Jul 25, 2025
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11 changes: 11 additions & 0 deletions docs/core/runtime-config/threading.md
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Expand Up @@ -31,6 +31,17 @@ This article details the settings you can use to configure threading in .NET.
| **runtimeconfig.json** | N/A | N/A |
| **Environment variable** | `COMPlus_Thread_AssignCpuGroups` or `DOTNET_Thread_AssignCpuGroups` | `0` - disabled<br/>`1` - enabled |

## Set the size of stack for VM-created threads
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## Set the size of stack for VM-created threads
## Set the stack size for threads created by the .NET runtime

I do not think we use "VM" in the official docs when referring to the runtime


- The default size of stack is dictated by VM and OS policies.
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- The default size of stack is dictated by VM and OS policies.
- The default stack size is dictated by .NET and OS policies. The default stack size for .NET apps is 1.5MB on Windows and macOS, and 8MB on Linux. The default stack size when .NET runtime is hosted (e.g. COM components) is dictated by the hosting process.

We can document the defaults while we are on it.

- This setting allows overriding the default.
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- This setting allows overriding the default.
- This setting allows overriding the default for threads created by .NET runtime. For example, threads created by [`System.Threading.Thread`](https://learn.microsoft.com/en-us/dotnet/api/system.threading.thread.-ctor) API.

- The specified size should be between 64 kB and 2 GB and a multiple of the natural allocation granularity of the OS.
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a multiple of the natural allocation granularity of the OS

Can we align the size up in the implementation so that this does not need to be documented? I think it is only a problem on Windows. This should behave just like the stackSize argument for System.Threading.Thread constructor where we do the same.


| | Setting name | Values | Version introduced |
| - | - | - | - |
| **runtimeconfig.json** | `System.Threading.DefaultStackSize` | A decimal integer that specifies the size of stack | .NET 10 |
| **Environment variable** | `DOTNET_Thread_DefaultStackSize` | A hexadecimal integer that specifies the size of stack | .NET 10 |

## Minimum threads

- Specifies the minimum number of threads for the worker thread pool.
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