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Increasing number of threads in ThreadPool
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Paul Ireland
Does anyone know how to increase the number of threads in the ThreadPool?
The MSDN docs state:

"The thread pool has a default limit of 25 threads per available processor,
which could be changed using CorSetMaxThreads as defined in the mscoree.h
file."

Any ideas which component implements CorSetMaxThreads so I can call it?

Being able to set the max number of threads in the thread pool is important
because classes such as HttpWebRequest use thread pools.

Paul Ireland
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Willy Denoyette [MVP] (VIP)
Sure you can, but you have to create a Interop assembly by hand (tlbimp is of no help here) based on the definitions in mscoree.h.

-------------------------------------
using System;
using System.Runtime.InteropServices;

/*
class DECLSPEC_UUID("CB2F6723-AB3A-11d2-9C40-00C04FA30A3E")

CorRuntimeHost;

*/

[
Guid("CB2F6723-AB3A-11D2-9C40-00C04FA30A3E"),
ComImport
]
class CorRuntimeHost
{
}
/*

MIDL_INTERFACE("84680D3A-B2C1-46e8-ACC2-DBC0A359159A")

ICorThreadpool : public IUnknown

*/

[
Guid("84680D3A-B2C1-46e8-ACC2-DBC0A359159A"),
InterfaceType(ComInterfaceType.InterfaceIsIUnknown)
]
interface ICorThreadPool
{
void slot0(); // v-table dummy slots, as you are only interested in the max threadpool settings
void slot1();
void slot2();
void slot3();
void slot3();
void slot4();
void slot5();
void slot6();
void CorSetMaxThreads( uint MaxWorkerThreads, uint MaxIOCompletionThreads );
void CorGetMaxThreads( out uint MaxWorkerThreads, out uint MaxIOCompletionThreads );
void CorGetAvailableThreads( out uint AvailableWorkerThreads, out uint AvailableIOCompletionThreads );
}

------------------------------

Compile this into a library and call it as:

.....

uint maxWorkerThreads;
uint availWorkerThreads;
uint maxIOThreads;
uint availIOThreads;

ICorThreadPool clrTp

clrTp = (ICorThreadPool)new CorRuntimeHost();

clrTp .CorGetMaxThreads(out maxWorkerThreads, out maxIOThreads);
clrTp .CorGetAvailableThreads(out availWorkerThreads, out availIOThreads);

clrTp .CorSetMaxThreads(...
....

Willy.

"Paul Ireland" <Click here to reveal e-mail address> wrote in message news:u9I8e#l1BHA.2212@tkmsftngp05...
[Original message clipped]
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Paul Ireland
Willy,

Nice one - works a treat. Any idea why Microsoft didn't expose this
functionality in a more user friendly way?

Paul

"Willy Denoyette [MVP]" <Click here to reveal e-mail address> wrote in message
news:e9UP7lq1BHA.2080@tkmsftngp04...
> Sure you can, but you have to create a Interop assembly by hand (tlbimp is
of no help here) based on the definitions in mscoree.h.
[Original message clipped]
Reply to this message...
 
    
Tom Kaiser
Just to add a point here, increasing the number of threads in the
threadpool may only delay the problem. My first question would be why am I
running out of threadpool thread.

"Paul Ireland" <Click here to reveal e-mail address> wrote in message
news:OqNuKEi2BHA.1260@tkmsftngp04...
[Original message clipped]
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Stephen Anders
Willy, Thanks for this code. I have compiled this and it performs correctly, but I have not been able to get it to work from VB.NET. I referenced the dll from my VB project and try to call it in a similar fashion as you described for C#. Is there something else that needs to be done for this to work in VB.NET?
Here is what I have:
...
Private Sub SetMaxThreads()
Try
Dim maxWorkerThreads As UInt32
Dim maxIOThreads As UInt32
Dim newWorkerThreads As UInt32
Dim newIOThreads As UInt32

Dim CLR_ThreadPool As ICorThreadPool
Dim runtimeHost As New CorRuntimeHost

CLR_ThreadPool = CType(runtimeHost, ICorThreadPool)

CLR_ThreadPool.CorGetMaxThreads(maxWorkerThreads, maxIOThreads) '<-- after this call, both are still 0

maxWorkerThreads = 15 'set them here
maxIOThreads = 10

CLR_ThreadPool.CorSetMaxThreads(maxWorkerThreads, maxIOThreads) '<-- this throws an exception that is not caught by the try-catch block and halts program execution

CLR_ThreadPool.CorGetMaxThreads(newWorkerThreads, newIOThreads)

Catch ex As Exception ' I never get here
LogMessage(ex.Message, EventLogEntryType.Error, "PollingService.SetMaxThreads")
End Try
End Sub

The Try-Catch block does not catch the exception. When I step through the code, when I execute the .CorSetMaxThreads, I get a runtime exception that halts program execution instead of going to the catch block. Very curious...
Am I missing something, or is this not possible from VB.NET?
Thanks
--------------------------------
From: Stephen Anders
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Brad Wilson
> Does anyone know how to increase the number of threads in the ThreadPool?

If I remember a thread pool discussion from correctly (it was a while ago),
the .NET thread pooling stuff is tied to the thread pooling in Win32, which
has a fixed thread pool size. It's almost certain that if you can change the
size of the thread pool, that those Cor* functions are meant to be called by
the unmanaged host, not from within .NET.

Brad

--
Read my weblog at http://www.quality.nu/dotnetguy/
Reply to this message...
 
 
System.Diagnostics.EventLogEntryType
System.Net.HttpWebRequest
System.Runtime.InteropServices.ComInterfaceType
System.Threading.ThreadPool
System.UInt32




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