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[archive] Windows thin client limit?

[Migrated content. Thread originally posted on 22 January 2004]

Has anyone ran into a limit on a windows server as to the number of thin clients that can be started? I can only start about 68-70 thin clients. The next one hangs until one of the other clients is terminated. If I try to start another one, I get a message that the connection failed and to check messages on the server, but I can find no messages on the server.
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RE: [archive] Windows thin client limit?

This might be a limit to Windows. I suggest you try to start the similar amount of number of another app that uses ports, for instance telnet and see if it has the same limitation.
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RE: [archive] Windows thin client limit?

Unfortunately my windows server will only allow 2 telnet connections. Any other applications that I could try?
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RE: [archive] Windows thin client limit?

How about ftp?
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RE: [archive] Windows thin client limit?

We have the same problem using acuconnect and there is an ID for this problem 15534.

We are running 5.2.1 on windows 2000 and 2003. It has been identified as a problem and I have not heard back yet.

If you are running windows 2003 we where able to create a second port and double the threads. Windows 2000 will let you create a second port but does not increase the threads.
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RE: [archive] Windows thin client limit?

We are currently looking into this problem. Just for a bit of information, the AcuRCL process itself is never notified when the refused connection is refused - it is the network layer that is refusing the connection. We are looking into why this is, and so far have no answers.
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RE: [archive] Windows thin client limit?

We have discovered the reason for this. It turns out it is a limitation of Windows. After a lot of pain and agony (I've been working on almost nothing else for the past week) I've discovered that the runtime is exiting with an exit status of 128, which is the situation described in the Microsoft Knowledge Base article 184802 (http://support.microsoft.com/default.aspx?scid=http://support.microsoft.com:80/support/kb/articles/q184/8/02.asp&NoWebContent=1). Read that article for a full description of the problem.

The short answer is that modifying the registry allows more clients to connect (but at what other adverse cost, we don't know). After reading the article above, you will find a reference to a part of a registry value called SharedSection, which has three numbers associated with it. The third number describes the amount of heap that noninteractive desktops get. By shrinking this number from the default of 512 to 128, we ran out of virtual memory before we hit the limit of thin clients we could connect (still only about 230, but that's probably because of the small amount of memory in the server we are using - your results will vary). It is not clear to me what effect modifying the registry will have on other servers that need non-interactive desktops, and so you should experiment with this value (on a non-production machine) until you find a value that works with all your Windows services.

Finally, we have a new ECN (scheduled for release in version 6.2) that allows you to detect this limitation. Ask about ecn AC050 from your usual source - AcuRCL traces will now show exit codes of child runtimes that halt within a few milliseconds of starting (and an exit code of 128 tells that you have hit this limitation).

Hope this helps,
Randy
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RE: [archive] Windows thin client limit?

Thanks a lot for your help in solving this problem!
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