RE: Asynchronous vs Synchronous network communication

Tech-Archive recommends: Repair Windows Errors & Optimize Windows Performance

From: Daniel Roth [MSFT] (daroth_at_online.microsoft.com)
Date: 01/01/05 

Date: Sat, 01 Jan 2005 01:16:41 GMT

In response to your second question about network throttling, some bandwidth management should be performed by the underlying Winsock implementation. You should
probably make sure you set a limit on the total number of outstanding requests so that you don’t build up an ever-growing backlog. For example, if you need to do a DNS
lookup and there’s 1000 already pending, the new one shouldn’t be allowed.

At the DNS protocol level, you could implement a simple wait and retry algorithm. For example, the first time out could be set to 1 second and the retry count could be set to
3. Each time the UDP request has timed out, multiply the timeout by 3 or some other constant factor and retry.

Daniel Roth

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| From: daroth@online.microsoft.com (Daniel Roth [MSFT])
| Organization: Microsoft
| Date: Fri, 31 Dec 2004 18:21:38 GMT
| Subject: RE: Asynchronous vs Synchronous network communication
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| Hi Noel,
|
| The benefit of doing asynchronous network communication is that you maximize the use of you processing power. Synchronous calls will waste processing time as your
| program waits for network communication to occur.
|
| To perform asynchronous operations, some sort of threading model must be used. A simple example would be to use one thread per request. Unfortunately, there is
| overhead associated with threading, so this simple example does not scale well. The threading model used by the .NET Framework takes advantage of Windows I/O
| Completion Ports (a form of thread pooling) in order to achieve maximum scalability. For optimal performance, the asynchronous pattern should always be used.
|
| Daniel Roth
|
|
| --------------------
| | From: noelhustler@gmail.com (Noel)
| | Newsgroups: microsoft.public.dotnet.framework.clr
| | Subject: Asynchronous vs Synchronous network communication
| | Date: 5 Dec 2004 20:10:22 -0800
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| |
| | Hi,
| | I am a tad confused about if there are any benefits from using
| | asynchronous vs synchronous network communication.
| | As my example, I have been writing a dns lookup stack with a network
| | communication class switchable between asynchronous and synchronous.
| | When I use asynchronous udp communication I find that if I want to
| | process a large amount of dns lookups I have one dns provider with
| | many state objects passing through (and a high object churn rate). If
| | I use synchronous udp communication I don't need state objects, but
| | have many providers each in a thread (although these providers are
| | static and so there is low churn).
| | It seems to me that both methods amount to the same result other than
| | the fact that using asynchronous communication results in a higher
| | object churn rate (leading to higher memory usage).
| | Can anybody clarify whether there really is an advantage in using one
| | over the other?
| |
| | My second question is a bit of a throwaway. Using whatever network
| | communication, what kind of techniques exist to throttle something
| | like this based on available bandwidth?
| |
| | Thanks,
| | Noel
| |
|
|
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