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
*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
--
Best regards, Sergey.
