RFR: 8185862: AWT Assertion Failure in ::GetDIBits(hBMDC, hBM, 0, 1, 0, gpBitmapInfo, 0) 'awt_Win32GraphicsDevice.cpp', at line 185 [v6]

[Christoph Langer]

On Fri, 23 Feb 2024 13:44:15 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 with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains ten additional commits since the last revision:
> 
>  - Reflect display detection in java.awt.GraphicsEnvironment::isHeadless()
>  - Merge branch 'master' into JDK-8185862
>  - Get rid of global variables and restore old handling wrt calling ::GetDIBits
>  - Merge branch 'master' into JDK-8185862
>  - Little cleanup
>  - Review Feedback Alexey
>  - Merge branch 'master' into JDK-8185862
>  - Add comments
>  - JDK-8185862

I think I've understood the problem behind the crashes now. The way I implemented `PlatformGraphicsInfo::getDefaultHeadlessProperty()` modifies graphics initialization. I will change the implementation to just count the monitor number once for `PlatformGraphicsInfo::getDefaultHeadlessProperty()`, independently of when `initDisplays()` is running. Will post an update soon...

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PR Comment: https://git.openjdk.org/jdk/pull/17614#issuecomment-1971591643