<AWT Dev> [9] Review request for 7155957: closed/java/awt/MenuBar/MenuBarStress1/MenuBarStress1.java hangs on win 64 bit with jdk8

[Anton V. Tarasov]

Hi Semyon,

The fix looks fine to me. Please, add its description to JIRA as well.

Regards,
Anton.

On 15.04.2015 17:38, Semyon Sadetsky wrote:
> Hello,
>
> Please review fix for JDK9.
> webrev: http://cr.openjdk.java.net/~ssadetsky/7155957/webrev.00/
> bug: https://bugs.openjdk.java.net/browse/JDK-7155957
>
> *THE ROOT CAUSE
> A number of concurrency bugs in AWT Toolkit.
> When menus are modified concurrently there is a big chance that the internal Windows menu events 
> are handled at the same time on the AWT-Windows thread which is not synchronized. If the internal 
> event processing on AWT-Windows calls Java side methods the JVM can die silently.
>
> *SOLUTIONS
> A number of fixes in various Java and C++ classes are introduced to eliminate (with finite 
> probability) concurrency problems :
>
> 1. java.awt.Menu.remove(int)
>
> The peer.delItem(index) is called after mi.removeNotify(). That means that dispose event will be 
> sent earlier than the menu remove WinAPI call. This causes Access Violation exception because 
> Windows events may come with deallocated references.
> The solution is to call them in the right order.
>
> 2. java.awt.MenuBar.remove(int)
> Same error as in 1 for menu bar.
>
>
> 3. java.awt.MenuComponent.serFont(Font)
> This method should hold tree lock while running otherwise its concurrent execution causes Access 
> Violation in number of places and JVM is crashed.
>
> 4. awt_Menu.cpp
> AwtMenu::GetItem(jobject target, jint index), AwtMenu::DrawItems(), AwtMenu::MeasureItems(
>
> Calling java.awt.Menu.getItem() during internal windows event processing can throw 
> ArrayIndexOutOfBoundException because number of menu items could be changed concurrently and the 
> index is not in range. This causes a hidden exception which is only seen in debug mode as an 
> Assertion error.
>
> Another issue here is request to GetPeerForTarget() for the menu item peer which can be 
> concurrently deleted on the Java side as result of Menu.delNotify() execution. It causes NPE peer 
> which is also hidden and only reveals itself as an Assertion error in debug mode.
>
> The solution for all is to abort and return windows event callback if the menu structure was 
> changed concurrently.
>
> 5. awt_MenuBar.cpp AwtMenuBar::GetItem()
>
> Same solution as 4 for menu bar in similar situations.
>
> 6. awt_MenuItem.cpp AwtMenuItem::Dispose()
>
> The "destroyed" filed should be set for the peer before pData is set to NULL otherwise "NPE null 
> pData" can be thrown in various concurrent situations.
>
> 7. awt_new.cpp safe_ExceptionOccurred()
>
> This routine is called evrywere in the code to check exceptions. It only stops execution and 
> prints to console if OOE happened, but other exceptions are re-thrown silently and execution 
> continues without any warnings. If the call is initiated by an internal Windows event callback the 
> exceptions are hidden in the release mode and shown in the debug mode as the Assertion Error 
> message box, but in the last case without any useful information because GetLastError() is always 
> 0 in such situations.
> I have added env->ExceptionDescribe() to print exception stack trace on the console for all debug 
> and release modes. This should help to detect internal toolkit issues during testing by JCK and 
> jtreg. Later before the JDK9 release we can leave it for debug mode only.
>
> *A KNOWN PROBLEM DID NOT FIXED
> When font is assigned to a menu item concurrently there is a big chance that menu item size will 
> be calculated with one font while drawing of the item will be performed with another font. In such 
> situation label of the menu item does not fit its size or vice versa.
> This is due to nature how the Windows OS handles owner-drawn menus.
>
> --Semyon
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