RFR: 8185862: AWT Assertion Failure in ::GetDIBits(hBMDC, hBM, 0, 1, 0, gpBitmapInfo, 0) 'awt_Win32GraphicsDevice.cpp', at line 185 [v8]

[Phil Race]

On Fri, 1 Mar 2024 08:01:08 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.
>
> Christoph Langer has updated the pull request incrementally with one additional commit since the last revision:
> 
>   load awt.dll before display check

This now passes all my automated testing.
Have you tested manual apps like SwingSet ? 
I doubt they'll have a problem but it would be good to be 100% sure.

The only thing I notice here is it adds one more place that we duplicate the code to load the AWT native library. Bizarrely Toolkit *and* WToolkit both do it.
The result is not just duplicated code but duplicated (now triplicated) effort at startup.
There might even be a fourth place - NativeLibLoader.
But fixing that might mean being extra careful about not introducing circularities at start up and since the impact should be negligible I think it is out of scope for this fix.

So just let me know about the manual testing.

-------------

PR Review: https://git.openjdk.org/jdk/pull/17614#pullrequestreview-1914948095