Non-Interactive Desktop Heap Size

Overview

Non-interactive desktop heap size settings are crucial for any service that spawns processes. Adjusting the size of that heap (within reason) has long been a recommended way of tuning the capabilities of any specific server.

In our installation, we check for the default setting of 512 KiB and suggest setting it to 3072 KiB (the same recommendation that other software vendors make). However, it seems newer systems have the default set to 786 KiB, so there is no warning at installation time.

The size of the heap will limit the total number of processes you can run (and therefore the total number of spawned processes) on a single server.

While 768 KiB might be enough for a desktop system, it may be beneficial to increase the non-interactive desktop heap size on your web server system to allow for more non-interactive desktops (processes).

Modifying the Heap Size

To increase the non-interactive desktop heap size, you will need the registry editor to modify the following key:

As always, please make a backup before modifying the registry.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\SubSystems\Windows

After opening the Windows key, the value data should contain something similar to the value below:

%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

Find SharedSection and change the third value, in this case 768, to 3072.

After changing the SharedSection value, reboot the web server.

FAQ

Q: I changed my non-interactive desktop heap size and now DataFlexWebAppCheck reports a red icon - Error?

A: You may have entered an incorrect value, added spaces, or corrupted the value data. Please restore the key from your backup.

Q: I gave my non-interactive desktop size a value of 4096 KiB and DataFlexWebAppCheck reports an orange icon - Warning?

A: In general, a non-interactive desktop heap size of 3072 KiB is considered safe. Anything above this needs very thorough testing. If you want to go beyond 3072 KiB, increase the heap size in steps of 512 KiB.

Additional Resources

For more information, please read the following: