Dealing with WMI Timeouts (c#)

There was a question in the PowerShellCommunity.Org forums about WMI timeouts.

I did some digging and found there are several different types of timeouts that can affect your WMI queries. I’m still working through different scenarios and I’d appreciate any feedback.

The first type of timeout can occur if the machine that you are targeting does not respond to network traffic (it’s down, you have the wrong IP address, firewalled, etc..). Your WMI call will usually time out after around 20 seconds.

A partial solution to that type of timeout is to ping the machine first. If you can ping that machine, you’ve eliminated a number of potential problems. You still might have permission issues or firewall issues, but you are able to reach the machine.

The second time of timeout I’ve seen is when the connection is made, but the WMI call hangs and does not return.

A potential fix for this issue is to use the [WMISearcher] accelerator. In the options property of the resulting object, there is a ReturnImmediately property, which should be set by default to true.

$searcher = [WMISearcher]”

$searcher.Options.ReturnImmediately

The ReturnImmediately property being set to true requires that the invoked operation (the search) be done synchronously and return immediately. The enumeration of the results of the WMI call are handled after the return of this operation.

An alternative solution for this issue would be to check the Transaction timeout setting on the target machine. Run DCOMCnfg.exe and navigate to the Component Services->My Computer. Right click and choose properties. On the options tab, there is a timeout (in seconds) for DCOM transactions. The default value for this setting is 60 seconds. Fiddle with that at your own risk. Also, I haven’t had a chance to check for where that value is in the registry or see if there is a Group Policy setting for it. Setting this value should allow a failed WMI connection to timeout more quickly.

The third area in which I’ve found timeouts/hangs in WMI queries is during the enumeration of the query results.

There is a property in options for the WMI class accelerator called Timeout, which sets the length of time between enumerations before timing out. The options property is hidden in the default view of PowerShell, so you will need to access it via the psbase property.

The timeout value is a System.TimeSpan object. You can specify the value with a TimeSpan object, a number of ticks, or a string that can be cast to a TimeSpan.

It can be set like this:

$wmi = [wmi]”

$wmi.psbase.options.timeout =’0:0:2′ #String that will be cast to a two second TimeSpan

You can also set a timeout value for the [WMISearcher] accelerator.

$searcher = [WMISearcher]”

$searcher.Options.timeout = ‘0:0:2′

WMI timeouts can be aggravating, hopefully one of these solutions will help mitigate your WMI woes.

http://blog.usepowershell.com/2009/01/dealing-with-wmi-timeouts/

[C#]
ManagementObjectSearcher s = new ManagementObjectSearcher(
"root\\MyApp",
"SELECT * FROM MyClass",
new EnumerationOptions(null, InfiniteTimeout, 1, true, false, true);

http://msdn.microsoft.com/en-us/library/aa329203(VS.71).aspx

EnumerationOptions Members

Timeout

Gets or sets the time-out to apply to the operation. Note that for operations that return collections, this time-out applies to the enumeration through the resulting collection, not the operation itself (the ReturnImmediately property is used for the latter). This property is used to indicate that the operation should be performed semi-synchronously. (Inherited from ManagementOptions.)

http://msdn.microsoft.com/en-us/library/aa329203(VS.71).aspx