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

Sergey Bylokhov Sergey.Bylokhov at oracle.com
Thu Apr 16 15:41:33 UTC 2015

Hi, Semyon.
Please mark all related fields in WObjectPeer as volatile( pData/ 
destroyed/etc). Probably MenuComponent.font field also?
That could be a reason for similar random issues.

On 15.04.15 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
> 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.
> 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.
> 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

Best regards, Sergey.

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