**Analysis:**
We are encountering a race condition in the native code. While retrieving the
screen number by calling _getScreenImOn(), the window is disposed. As a result,
the AWT-Windows event loop processes the Dispose() call, which triggers
UnlinkObjects().
The race condition between the execution paths of these two native methods
sometimes causes an exception
**Proposed Fix:**
While it's possible to introduce a synchronization mechanism, it would not
offer any real benefit. The window will be disposed regardless, and we’ll fall
back to the default screen. This behavior is already handled in
WWindowPeer.java, where a workaround is in place to use the default device when
getScreenImOn() returns a non-existent screen number
public void updateGC() {
int scrn = getScreenImOn();
if (screenLog.isLoggable(PlatformLogger.Level.FINER)) {
log.finer("Screen number: " + scrn);
}
// get current GD
Win32GraphicsDevice oldDev = winGraphicsConfig.getDevice();
Win32GraphicsDevice newDev;
GraphicsDevice[] devs = GraphicsEnvironment
.getLocalGraphicsEnvironment()
.getScreenDevices();
// Occasionally during device addition/removal getScreenImOn can return
// a non-existing screen number. Use the default device in this case.
if (scrn >= devs.length) {
newDev = (Win32GraphicsDevice) GraphicsEnvironment
.getLocalGraphicsEnvironment().getDefaultScreenDevice();
} else {
newDev = (Win32GraphicsDevice) devs[scrn];
}
}
Therefore, I propose modifying the native method getScreenImOn to return the
default device if the peer is being disposed :
jint AwtWindow::_GetScreenImOn(void *param)
{
...
jboolean destroyed = JNI_GET_DESTROYED(self);
if (destroyed == JNI_TRUE){
env->DeleteGlobalRef(self);
return AwtWin32GraphicsDevice::GetDefaultDeviceIndex();
}
...
**Tests Summary:**
GetGraphicsStressTest (existing test):
Fails intermittently without the fix
Consistently passes with the fix
NotifyStressTest (newly added test):
Consistently fails without the fix
Consistently passes with the fix
-------------
Commit messages:
- Handle white spaces
- remove extra-space
- Update copyright
- Return the default device if the peer is beeing disposed
- Add Test for JDK-8346952
Changes: https://git.openjdk.org/jdk/pull/25619/files
Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25619&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8346952
Stats: 66 lines in 2 files changed: 66 ins; 0 del; 0 mod
Patch: https://git.openjdk.org/jdk/pull/25619.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/25619/head:pull/25619
PR: https://git.openjdk.org/jdk/pull/25619
