Screen freezes for a few seconds

Hi Apple

I have the same issue with my Mac Pro freezing randomly for a few seconds. I have noticed the Kernel_task and the hide performing in the monitor every time it freezes.

We really need your help to solve this issue.

Bad news guys... It's back.. Took a few days before it showed up. I guess we can rule out the screen ! I still think its software related (Mac OSX) not our own software.

virtual IOReturn IOAccelEventMachine2::waitForStamp(int32_t, stamp_t, stamp_t *): initial wait for 1 second expired. Continue wait for 4 seconds. stamp 1334904 (gpu_stamp=1334903)

Thank you for updating us. I had started to price replacement screens online. I keep hoping there will be a specific cause and solution to resolve this issue so that we can put the "virtual IOReturn IOAccelEventMachine2" bug to rest once and for all. Unfortunately I think we are SOL without Apple to assist in tracing and killing this bug.

Has anyone with the "virtual IOReturn IOAccelEventMachine2" bug started running betas of 10.15 yet???

I am trying to see if I have this sort of problem but may not know exactly how to examine the logs for it. Can you tell me specifically what to do in Console? My computer freezes for 90 seconds or more at a time. While it is frozen, the time on the top bar does not change. Occasionally it freezes up a second time for a shorter interval a few seconds later. When it unfreezes, typically a lot of action happens on the screen, perhaps from accumulated keystrokes.

Does this sound like the same sort of thing as you are describing?

I haven't had a really long crash today that froze the time as they usually do. But I did have a kernel(IOAcceleratorFamily2). In full: /System/Library/Extensions/IOAcceleratorFamily2.kext/Contents/MacOS/IOAcceleratorFamily2 . Don't know if that is related or not. Is it okay to just keep this Console window open and expect that the crashes will continue to show there?

Really? Though the install process didn't change much.

If you are talking about Gatekeeper, just can run:

#sudo spctl --master-disable

Not something that would prevent me from upgrading to the latest version.

It is not just a Safari issue on my iMac. Having ditched Safari the last couples of months, and used Chrome instead, the problem persists with that browser. So it is not Safari that is the problem here. But perhaps it is WebKit? I’m still using Apple Mail, and it uses WebKit? So. ... ?

Okay. As mentioned in older replies by others, it is not only issued by Safari. Taking focus on WebKit - it is software related, developed by Apple, which does not support hardware, sold by Apple last year.

Before anyone gets their hopes up, I just wanted to report that after installing macOS Catalina Public Beta 4, I tried giving Safari another chance. I had it open for about 5 minutes before the freeze returned. Amazingly, I just had another one while trying to type this post about 10 minutes later.

Do NOT expect Catalina to solve the problem at this point.

I just started having this problem, (summer 2019) on my MacBookPro 15" [2015] with Retina display & Intel Iris Pro / same setup as noted repeatedly above. But this has been only with Mojave (now 10.14.6).

Same GPU error as everyone else :(

I can confirm that the potential is there, at least, though it's not absolute proof. I am not sure why they would use a web-based store and not use webkit though.

# otool -l /Applications/App\ Store.app/Contents/MacOS/App\ Store | grep -i store                 
/Applications/App Store.app/Contents/MacOS/App Store:
         name /System/Library/PrivateFrameworks/StoreFoundation.framework/Versions/A/StoreFoundation (offset 24)
         name /System/Library/PrivateFrameworks/AppStoreUI.framework/Versions/A/AppStoreUI (offset 24)
         name /System/Library/PrivateFrameworks/StoreUI.framework/Versions/A/StoreUI (offset 24)
         name @rpath/AppStoreKitMac.framework/Versions/A/AppStoreKitMac (offset 24)
         name /System/Library/PrivateFrameworks/AppStoreDaemon.framework/Versions/A/AppStoreDaemon (offset 24)
# otool -l /System/Library/PrivateFrameworks/StoreUI.framework/Versions/A/StoreUI | grep -i webkit
         name /System/Library/Frameworks/WebKit.framework/Versions/A/WebKit (offset 24)

I left the app store open for the last ten minutes and waited for a freeze:

fault	23:44:33.589442 +1200	kernel	virtual IOReturn IOAccelEventMachine2::waitForStamp(int32_t, stamp_t, stamp_t *): timeout waiting for IntelAccelerator stamp 6214080 (gpu_stamp=6214079)
fault	23:44:33.589466 +1200	kernel	void IOAccelEventMachine2::handleFinishChannelRestart(IOReturn, int32_t, uint32_t) - Setting restart type to 4
fault	23:44:33.589470 +1200	kernel	void IOAccelEventMachine2::handleFinishChannelRestart(IOReturn, int32_t, uint32_t): GPURestartDequeued stampIdx=4 type=4 fromWhere=1 waitingOnIdx=4
default	23:44:33.589474 +1200	kernel	[IGPU] display event timeout on index = 4
fault	23:44:33.589523 +1200	kernel	void IOAccelEventMachine2::restart_channel(): GPURestartSkipped stampIdx=4 type=4
fault	23:44:33.589526 +1200	kernel	void IOAccelEventMachine2::restart_channel(): no channel associated with stamp_idx 4 (type 4)

Is it logging those same messages, or is it just pausing because of some other activity? I'm not seeing pauses for opening rarely used apps, I'm seeing it when leaving webkit active for long enough in certain situations (possibly related to video playback, but I'm not confident of that).

If you are seeing the same messages on a new machine, then we still have hope that they will fix the problem.

BDAqua wrote:

or maybe it's a bug in APFS...

I can confirm that it is not due to APFS.

I bought my MacBook Pro Mid 2015 recently from a refurbisher. It came with 10.13 High Sierra installed on the SSD formatted as HFS+, not APFS.

I'm seeing exactly the same thing, resolution is set to default for display.

Model Name:	MacBook Pro
  Model Identifier:	MacBookPro11,4
  Processor Name:	Intel Core i7
  Processor Speed:	2.2 GHz
  Number of Processors:	1
  Total Number of Cores:	4
  L2 Cache (per Core):	256 KB
  L3 Cache:	6 MB
  Memory:	16 GB
  Boot ROM Version:	MBP114.0184.B00
  SMC Version (system):	2.29f24

System Version:	macOS 10.13.6 (17G65)
  Kernel Version:	Darwin 17.7.0

fault	20:46:02.485182 -0700	kernel	virtual IOReturn IOAccelEventMachine2::waitForStamp(int32_t, stamp_t, stamp_t *): initial wait for 1 second expired. Continue wait for 4 seconds. stamp 8499757 (gpu_stamp=8499756)
fault	20:46:06.485280 -0700	kernel	virtual IOReturn IOAccelEventMachine2::waitForStamp(int32_t, stamp_t, stamp_t *): timeout waiting for IntelAccelerator stamp 8499757 (gpu_stamp=8499756)
fault	20:46:06.485301 -0700	kernel	void IOAccelEventMachine2::handleFinishChannelRestart(IOReturn, int32_t, uint32_t) - Setting restart type to 4
fault	20:46:06.485306 -0700	kernel	void IOAccelEventMachine2::handleFinishChannelRestart(IOReturn, int32_t, uint32_t): GPURestartDequeued stampIdx=4 type=4 fromWhere=1 waitingOnIdx=4
fault	20:46:06.485364 -0700	kernel	void IOAccelEventMachine2::restart_channel(): GPURestartSkipped stampIdx=4 type=4
fault	20:46:06.485367 -0700	kernel	void IOAccelEventMachine2::restart_channel(): no channel associated with stamp_idx 4 (type 4)