RFR: 8185862: AWT Assertion Failure in ::GetDIBits(hBMDC, hBM, 0, 1, 0, gpBitmapInfo, 0) 'awt_Win32GraphicsDevice.cpp', at line 185

[Matthias Baesken]

On Mon, 29 Jan 2024 14:24:43 GMT, Christoph Langer <clanger at openjdk.org> wrote:

> The assertions reported in the bug were observed spuriously and here and there broke tests in some Windows configurations.
> For instance [JDK-8266129](https://bugs.openjdk.org/browse/JDK-8266129), [JDK-8269529](https://bugs.openjdk.org/browse/JDK-8269529) or [JDK-8323664](https://bugs.openjdk.org/browse/JDK-8323664) came up due to this.
> 
> The problem is that in Windows environments without a valid display, e.g. started by system services or via PowerShell Remoting, one sees a Monitor with name 'Windisc' in `EnumDisplayMonitors`.
> However, it seems to be some kind of a pseudo device where you can not get a DC via `CreateDC`. This behavior/monitor type doesn't seem to be well documented, though.
> 
> I hereby modify the device initialization code to only count/detect monitors where CreateDC returns non-NULL in Devices.cpp. I also add some more checking/error handling to AwtWin32GraphicsDevice::Initialize() for correctness.
> 
> Furthermore, I re-enable the test `javax/swing/reliability/HangDuringStaticInitialization.java` for Windows Debug VMs, which reverts the fix from JDK-8269529 that should not be necessary any more.

Maybe add some comment about the monitor counting, that it only considers now certain monitors with 'good' capabilities ?
Or even rename the count function and use a better name indicating what it does now ?

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PR Comment: https://git.openjdk.org/jdk/pull/17614#issuecomment-1914850222