[OpenJDK 2D-Dev] <AWT Dev>  Review request for 8005607: Recursion in J2DXErrHandler() Causes a Stack Overflow on Linux
anton.litvinov at oracle.com
Fri Jan 11 10:03:54 UTC 2013
Thank you very much for the review of this request. Yes, you understood
the description of the bug correctly. After several discussions with
Artem I also was recommended to redesign J2DXErrHandler() as a Java
synthetic handler and to exploit
"sun.awt.X11.XTookit.WITH_XERROR_HANDLER" through JNI from all the
places in native code which currently set/unset J2DXErrHandler(). I
managed to implement this solution, but it led to a crash with
IndexOutOfBoundsException not in places of
"src/solaris/native/sun/java2d/x11/X11SurfaceData.c" files, where
substitution for the Java synthetic handler was made, but in some other
AWT Java files handling fonts. I was not able to resolve this crash and
came to a conclusion that, perhaps, static initialization of
"sun.awt.X11.XToolkit" class in
void TryInitMITShm(JNIEnv *env, jint *shmExt, jint *shmPixmaps)
function of "src/solaris/native/sun/awt/awt_GraphicsEnv.c", which was
initiated by the code from the fix, should not have happened so early.
Probably, some mistake was done in implementation of the fix involving
JNI. Then I will try to return to the solution with synthetic handlers
On 1/9/2013 8:08 PM, Anthony Petrov wrote:
> Hi Anton et al.,
> If I read the description of the bug correctly, specifically this part:
>> The problem occurs, if another thread (for example, GTK thread) is
>> doing the same sort of thing concurrently. This can lead to the
>> following situation.
>> JVM thread: Sets J2DXErrHandler(), saves ANY_PREVIOUS_HANDLER as
>> previous GTK thread: Sets some GTK_HANDLER, saves
>> J2DXErrHandler() as previous JVM thread: Restores
>> ANY_PREVIOUS_HANDLER GTK thread: Restores J2DXErrHandler() JVM
>> thread: Sets J2DXErrHandler(), saves J2DXErrHandler() as previous
> It is obvious that at this final step 2D is in an inconsistent state.
> We don't expect to replace our own error handler (and it shouldn't
> have been there in the first place).
> I realize that the fix you propose works around this problem. But this
> doesn't look like an ideal solution to me.
> BTW, IIRC, in JDK7 (and 6?) we decided to set the actual X11 error
> handler only once and never replace it. All the rest of the
> push_handler/pop_handler logic is now located in Java code (see
> XToolkit.SAVED_ERROR_HANDLER() and the surrounding logic). I believe
> that we should somehow share this machinery with the 2D code to avoid
> this sort of problems. Though I'm not sure if this will eliminate this
> exact issue.
> 2D/AWT folks: any other thoughts?
> best regards,
> On 12/29/2012 17:44, Anton Litvinov wrote:
>> Please review the following fix for a bug.
>> Bug: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8005607
>> Webrev: http://cr.openjdk.java.net/~alitvinov/8005607/webrev.00
>> The bug consists in a crash which is caused by a stack overflow for
>> the reason of an infinite recursion in AWT native function
>> J2DXErrHandler() under certain circumstances on 32-bit Linux OS. The
>> fix is based on introduction of the logic, which detects indirect
>> recursive calls to J2DXErrHandler() by means of a simple counter, to
>> J2DXErrHandler() native function. Such a solution requires minimum
>> code changes, does not alter the handler's code significantly and
>> eliminates this bug.
>> Adding 2d-dev at openjdk.java.net e-mail alias to the list of recipients
>> of this letter, because the edited function's name is related to Java
>> 2D area of JDK, despite of the fact that the edited file is located
>> in AWT directory.
>> Thank you,
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