[Mono-dev] Remoting and thread pool limits

[Robert Jordan]

Hi Pablo,

pablosantosluac wrote:
> Hi Robert,
> 
> Do you think it is related to the thread creation?

I don't think so. Most of the time is spent in TcpChannel:

System.Runtime.Remoting.Channels.Tcp.ClientConnection::ProcessMessages()
System.Runtime.Remoting.Channels.Tcp.TcpMessageIO::ReceiveMessageStatus(Stream,byte[])
System.Runtime.Remoting.Channels.Tcp.TcpMessageIO::StreamRead(Stream,byte[],int)

When I stop the test at 40 threads, these methods are not at the top
anymore.

Robert

> 
> I'll run some tests with the mono profiler on Linux and try to figure out 
> where the time is being lost...
> 
> 
> pablo
> 
> 
> 
> ----- Original Message ----- 
> From: "Robert Jordan" <robertj at gmx.net>
> To: <mono-devel-list at lists.ximian.com>
> Sent: Saturday, December 15, 2007 9:25 PM
> Subject: Re: [Mono-dev] Remoting and thread pool limits
> 
> 
>> pablosantosluac wrote:
>>> Well, it is not a *bug* but a feature. I wonder if it should be changed. 
>>> If
>>> you look into RemotingThreadPool.cs there is a line like:
>>>
>>>
>>> threadDone.WaitOne(PoolGrowDelay, false);
>>>
>>>
>>> This one is actually the one making the process too slow. I'm afraid it 
>>> must
>>> be something similar on the .NET code too!
>>>
>>> Of course removing this line the problem gets solved, but I guess there 
>>> is a
>>> reason in the channel to do that.
>> I noticed that too, but this doesn't solve the real problem: the 200
>> thread test is still too slow on my machine. The degradation seems to
>> start after 60-80 threads on my pretty weak SMP machine.
>>
>> Just to be sure,  I've replaced RemotingThreadPool with an own, simple
>> version based on the standard BCL ThreadPool => same issue, although
>> I've raised the env var MONO_THREADS_PER_CPU to an insane value.
>>
>> Robert
>>
>>>
>>> pablo
>>>
>>>
>>> ----- Original Message ----- 
>>> From: "Robert Jordan" <robertj at gmx.net>
>>> To: <mono-devel-list at lists.ximian.com>
>>> Sent: Saturday, December 15, 2007 4:12 PM
>>> Subject: Re: [Mono-dev] Remoting and thread pool limits
>>>
>>>
>>>> Hi,
>>>>
>>>> pablosantosluac wrote:
>>>>> Hi,
>>>>>
>>>>> I've found the following difference working with .NET and Mono 
>>>>> remoting.
>>>>> In
>>>>> .NET when the remoting ThreadPool reaches the pool's maximum (25 
>>>>> threads
>>>>> per
>>>>> process), it is able to continue creating new threads. In fact, you can
>>>>> end
>>>>> up having a remoting server with hundreds of threads.
>>>>>
>>>>> In mono the behaviour is different. Once the limit is reached it starts
>>>>> refusing connections.
>>>> This is unrelated to mono's remoting thread pool. You have probably
>>>> ran your tests on Windows, where mono indeed fails with a GC failure
>>>> when too many threads are created because the GC has a hard coded
>>>> max thread count limit.
>>>>
>>>> On Linux (x86_64, Mono 1.2.6) I can finish the tests:
>>>>
>>>> Linux Mono client -> Linux Mono server (same machine)
>>>>
>>>> poseidon [~/foo] $ mono client/bin/Debug/client.exe
>>>> tcp://localhost:8084/remote
>>>> 1 - Time 1206 ms
>>>> 5 - Time 2045 ms
>>>> 10 - Time 3575 ms
>>>> 20 - Time 8174 ms
>>>> 40 - Time 12055 ms
>>>> 50 - Time 8185 ms
>>>> 200 - Time 46150 ms
>>>>
>>>>
>>>> MS.NET client -> Linux Mono server (different machines)
>>>>
>>>> troll:/cygdrive/u/foo/client/bin/Debug $ ./client.exe
>>>> tcp://poseidon:8084/remote
>>>> 1 - Time 1297 ms
>>>> 5 - Time 2000 ms
>>>> 10 - Time 3515 ms
>>>> 20 - Time 6016 ms
>>>> 40 - Time 11031 ms
>>>> 50 - Time 6016 ms
>>>> 200 - Time 94375 ms
>>>>
>>>>
>>>> The numbers don't look very well, though. I promise to look at
>>>> this when you file a bug report so that it doesn't get
>>>> overlooked.
>>>>
>>>> Robert
>>>>
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