<AWT Dev> [11] Review Request: 8189604 possible hang in sun.awt.shell.Win32ShellFolder2$KnownFolderDefinition::<clinit>

[Krishna Addepalli]

Hi Sergey,

The fix looks fine. However, I have couple of comments:
1. The variable "result" in Java_sun_awt_shell_Win32ShellFolder2_loadKnownFolders at line 1401 is not initialized. Although it is initialized in the following if condition, I'm not sure when it return false, and lead to a return of garbage value to Java.

2. Could you clarify a bit about the testcase - how it triggers the hang/crash?

Thanks,
Krishna

-----Original Message-----
From: Sergey Bylokhov 
Sent: Monday, June 25, 2018 2:21 PM
To: awt-dev at openjdk.java.net
Subject: <AWT Dev> [11] Review Request: 8189604 possible hang in sun.awt.shell.Win32ShellFolder2$KnownFolderDefinition::<clinit>

Hello.
Please review the fix for jdk11.

Bug: https://bugs.openjdk.java.net/browse/JDK-8189604
Webrev: http://cr.openjdk.java.net/~serb/8189604/webrev.00

We have a cyclic dependency in Win32ShellFolder2$KnownFolderDefinition,
which can cause a deadlock if this class is initialized on "non-COM" thread.

1. - Static initialization of Win32ShellFolder2$KnownFolderDefinition
2. -- Win32ShellFolder2.getLibraries();
3. --- invoke Win32ShellFolder2.loadKnownFolders() on "COM-thread" and wait 4. ---- in the native call 
env->FindClass("sun/awt/shell/Win32ShellFolder2$KnownFolderDefinition");
5. ---- deadlock. because initialization of KnownFolderDefinition was blocked at step 3.

In the fix this dependency is broken, so the new class KnownLibraries is not depends from its own initialization.


-- 
Best regards, Sergey.