IE CPU Utilisation shoots to 100% on disconnected session

[NickBowie]

Hi all,

(I am in the process of logging an SR for this, but MyVMware isn't completing that so just posting here to cover the bases)

Infrastructure: View 6.0 on vSphere 5.5.0; Windows 8.1 virtual desktops with View Agent 6.

Quick summary:

If a user disconnects their PCoIP session leaving IE open with an HTML5 based page in the foreground, CPU reaches and maintains 100% utilization. When the user re-connects, utilization drops back to normal levels.

Microsoft support performed traces on the IE DCOMP process and the findings are below.

Leaving IE minimized when a user disconnects is fine. Firefox/Chrome also do not exhibit this, only IE.

Microsoft support response:

"The trace shows IE is waiting for the batch ID confirmation.

   +0x050 m_currentBatchId : 0x24bb57dc

   +0x054 m_lastConfirmedBatchId : 0x20e335b0

   +0x058 m_lastSurfaceProcessedBatchId : 0x20e335b0

The current batch ID keeps increasing, but the last confirmed batch id is never updated until the user Gary’s session resumed. The confirmed ID jumped from 0x20e335b0 to 0x24bb57da all of a sudden. After that, the IE UI thread jumped out the loop and resume to normal.

As a conclusion, we have some important findings:

• The CPU spike is observed after user disconnected the session, the monitoring tool will give out the warning.

• When logon using a different user, the CPU spike persists.

• When the disconnected session resumes, IE CPU drops to normal.

• However, when you disconnect the session with IE window displays, the CPU soon increased to 100%.

• We also did a test by minimize the IE window before disconnecting the session, and then the CPU stays normal and the issue doesn’t recur.

The dump we collected today shows the exact same issue as the previous dumps. DCOMP client is waiting for the confirmed ID to be updated. It seems when the VDI session is disconnected, DWM stops processing the content frame until the user session is active again."

Is there anything that can be done at the Horizon Agent side (via policy perhaps) that could mitigate this?

Thanks,

NickB

[mpryor]

This isn't a View fix, I don't think there's anything we can do about this Microsoft bug directly, but have you tried turning off hardware rendering in IE as a workaround? Internet Options->Advanced->Accelerated graphics->Use software rendering.

[NickBowie]

Hi,

Yep we've tried that via GPO and the symptoms persist even with that enabled/disabled.

I agree it's a MS bug but indications are that there's not going to be a patch to address this any time soon, hence wondering if there's anything we can do on the View side to assist

[mpryor · Accepted solution]

Sorry, I don't think there's anything we can do here directly - the product will explicitly disconnect the session, and there's no secure way to disable that. One workaround that may be possible - if you're using 6.0 then you can use CommandsToRunOnDisconnect and construct a script to minimize all IE windows. See VMware View 5.0 Documentation Center

[NickBowie]

Update for anyone stumbling on this topic through Google:

We have worked with VMware and Microsoft and Microsoft, and they have identified root cause to be within Windows 8.1. Sadly, the minimize-script invoked by CommandsToRunOnDisconnect doesn't consistently run in our case.

Until the hotfix is released, you will see this if you have the combination of:

• Windows 8.1
• IE11
• Horizon Agent using PCoIP as the display protocol

It is not seen with other browsers, RDP or if IE is minimized prior to disconnecting.

-Nb