I've read here that :
In v2.0, 3.5, and 4.0, ASP.NET initializes the CLR ThreadPool with 100 threads per processor(core)
That is correct , I checked it (I have 8 core machine , so 8*100 = 800):
But then I saw this and this:
maxWorkerThreads — Configures the maximum number of worker threads to use for the process on a per-CPU basis.The range for this attribute is from
5 through 100.
The default is20
.
Question
I don't see how the numbers fits in here :
The first paragraph states that I have max 100 threads per core ( the image prove it , I have 8 cores).
But the second paragraph states that the default maximum worker threads per core is 20. So if I have 8 cores then I must have 8*20 = 160 max threads. not 800.
Can someone please shed light?
Update:
I just found a way to get the key element value via c# code :
So now the number are fit in ,but still - MSDN say the default is 20 , not 100
And then they do mention 100 :
What is going on here?
ThreadPool will create maximum of 10 threads to process 10 requests at a time. After process completion of any single Thread, ThreadPool will internally allocate the 11th request to this Thread and will keep on doing the same to all the remaining requests.
By default, the MaxThreads of the ThreadPool is very high. Usually you'll never get there, your app will crash first. So when all threads are busy the new tasks are queued and slowly, at most 1 per 500 ms, the TP will allocate new threads.
The default upper limit of threads that the Thread pool will create by calling ThreadPool. SetMaxThreads ; 1023 in .
32767 in Framework 4.0 (64-bit environment)
I have looked at source code and have found that default value for MaxWorkerThreads
is set to 100
private static readonly ConfigurationProperty _propMaxWorkerThreads = new ConfigurationProperty("maxWorkerThreads", typeof (int), (object) 100, (TypeConverter) null, (ConfigurationValidatorBase) new IntegerValidator(1, 2147483646), ConfigurationPropertyOptions.None);
This field is added to properties collection in static constructor
ProcessModelSection._properties.Add(ProcessModelSection._propMaxWorkerThreads);
In property definition they do set default value to 20
[IntegerValidator(MaxValue = 2147483646, MinValue = 1)]
[ConfigurationProperty("maxWorkerThreads", DefaultValue = 20)]
public int MaxWorkerThreads
But this obviously give no effect. Maybe it's some kind of legacy implementation. By the way it behaves this way only if autoConfig
is set to false. When it's set to true I have 32K worker threads in my application. Probably this behavior depends on IIS version.
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