On Thu, 21 May 2026 15:14:38 GMT, Alexander Zvegintsev <[email protected]> wrote:
> [JDK-8185862](https://bugs.openjdk.org/browse/JDK-8185862) introduced several > behavioral changes: > > 1. `CountMonitors()` started counting only those `HMONITOR` from > `EnumDisplayMonitors` for which `CreateDC` was successful. > 2. A new state `0 valid monitors` appeared, which did not exist before. > 3. In `Devices::GetDevice`, the lower bound check was insufficient (`index < > 0` instead of `index <= 0`, this was not introduced by > [JDK-8185862](https://bugs.openjdk.org/browse/JDK-8185862) though). > Thus, we could attempt to read the first element of a zero-length array, > which caused a crash in `sun.awt.Win32GraphicsDevice.initNativeScale`. > 3. Invalidation only occurres for devices whose indices were removed from the > end of the array. > In RDP scenarios, a device may be replaced at the same index without changing > the total number of screens, which bypassed invalidation. > > --- > > Changes in this fix: > > 1. Combined `CountMonitors()` and `CollectMonitors()`. Monitors are now > collected into a dynamic array in a single pass. > 2. The working list of devices is no longer replaced by an empty one. > 3. `displayChanged()` is called only after a successful native update. > 5. Added RDP transient states handling (retries by timer and by session > connect). > 6. `GetDevice()` now returns `NULL` if `numDevices <= 0`. > 7. Improved device comparison logic: comparisons are now performed using > display data (`dwFlags`, `szDevice`). > Changed devices are invalidated, unchanged ones receive transferred Java > references to the new native device. > > --- > > Testing: > > The fix seems to be stable over various scenarios of changing display > configurations, locally and over RDP. > CI testing is also green. > > > > --------- > - [x] I confirm that I make this contribution in accordance with the [OpenJDK > Interim AI Policy](https://openjdk.org/legal/ai). src/java.desktop/windows/native/libawt/windows/awt_Win32GraphicsDevice.cpp line 628: > 626: } > 627: } > 628: Is it intentional that if objPtr == NULL that we release the jni ref to the old java device and set javaDevice = NULL ? It would make sense if this is the intended way to clear the javaDevice but I don't have the whole picture yet. If intentional an explanatory comment would help. src/java.desktop/windows/native/libawt/windows/awt_Win32GraphicsDevice.cpp line 649: > 647: env->DeleteWeakGlobalRef(javaDevice); > 648: } > 649: javaDevice = device->javaDevice; Why don't we need a new JNI ref here ? ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/31238#discussion_r3320221113 PR Review Comment: https://git.openjdk.org/jdk/pull/31238#discussion_r3320254068
