Is there a Windows limit to the number Process objects you can create and start?

Question

It seems there are questions close to this, but none I have seen involve the actual .Net Process object. Currently, I am using a Process object to start an external executable and read data from it in C#. This happens once for each collection point that I must monitor data for. However, when I have to monitor 5 or more collection points my process for the fifth collection point is killed before I can collect any data from it. The code used to start the Process object is list below. Any help is appreciated.

    procCollectionMonitor = new Process();
    procCollectionMonitor.StartInfo.FileName = options.CollectionMonitorProcessPath;

    procCollectionMonitor.StartInfo.WorkingDirectory = System.IO.Path.GetDirectoryName(options.CollectionMonitorProcessPath);
    procCollectionMonitor.StartInfo.ErrorDialog = false;

    procCollectionMonitor.StartInfo.UseShellExecute = false;

    procCollectionMonitor.EnableRaisingEvents = true;
    procCollectionMonitor.Exited += spawn_Exited;
    procCollectionMonitor.Start();

This application is a Windows Service, that runs on Windows Server 2008 R2. As I said before, this issue only occurs when 5 or more collection points are started. Instances where 4 or less are needed have no problems.

Answer 1

Since you are using a Windows Service, there is definitely a limit. The limit can be controlled through Desktop Heap. Check the below answer for more details on this:

How to increase the maximum number of child processes that can be spawned by a windows service -- desktop heap limits

You simply need to do the following:

Go to regEdit, and navigate to the key:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\SubSystems

Edit the key named "Windows" from:

%SystemRoot%\system32\csrss.exe ObjectDirectory=\Windows SharedSection=1024,20480,768 Windows=On SubSystemType=Windows ServerDll=basesrv,1 ServerDll=winsrv:UserServerDllInitialization,3 ServerDll=sxssrv,4 ProfileControl=Off MaxRequestThreads=16

to:

%SystemRoot%\system32\csrss.exe ObjectDirectory=\Windows SharedSection=1024,20480,2048 Windows=On SubSystemType=Windows ServerDll=basesrv,1 ServerDll=winsrv:UserServerDllInitialization,3 ServerDll=sxssrv,4 ProfileControl=Off MaxRequestThreads=16

Also this is supposed to fix the issue, I believe the optimum solution will be to find a work around to start the process independent from the Window service (which till now I don't know how)

Updated: I found a workaround to solve this issue... you can use the method "CreateProcessAsUser" for more details please check the below link:

https://www.codeproject.com/Articles/35773//Articles/35773/Subverting-Vista-UAC-in-Both-32-and-64-bit-Archite

Answer 2

There is no practical limit to the number of processes you can start. Starting five should certainly not be a problem. Your use of C# and .NET will not have an impact. The Process class in .NET is just a managed wrapper for the Win32 CreateProcess and ShellExecuteEx APIs. The problem must lie with program that you're launching. You'll need to analyze it to figure out what's going on.