[OpenJDK 2D-Dev] <Swing Dev> [14] RFR: JDK-8223158: Docked MacBook cannot start any Java Swing applications

Prasanta Sadhukhan prasanta.sadhukhan at oracle.com
Wed Oct 9 08:06:58 UTC 2019

Hi Sergey,

On 27-Sep-19 2:58 AM, Sergey Bylokhov wrote:
> Hi, Prasanta.
> On 9/25/19 11:13 pm, Prasanta Sadhukhan wrote:
>>> 2) I guess we don't need to free "attrs" or "attrs1" since it is 
>>> stack allocated ..
>>> Unfortunate that we have to repeat the entire initialisation minus 
>>> glMask.
>>> Can you think of a better way to do this ?
>> As per 
>> https://developer.apple.com/documentation/appkit/nsopenglpixelformat/1436219-initwithattributes?language=objc
>> |/* Check if initWithAttributes succeeded. */ if(pixFmt == nil) { /* 
>> initWithAttributes failed. Try to alloc/init with a different list of 
>> attributes. */ } it is appropriate to try with another list, which is 
>> what I tried here. Regards Prasanta |
> NSOpenGLPFAScreenMask attribute and its usage it is quite interesting. 
> It is used only once
> mostly at startup to initialize the "sharedPixelFormat" and 
> "sharedContext". Later we create
> context per GraphicsConfig on top of these "sharedPixelFormat" and 
> "sharedContext".
> In the single monitor configuration this logic is clear, we request 
> "sharedPixelFormat"
> which supports "NSOpenGLPFAScreenMask" for the main display and it 
> just work.
> But how it should work when the new screen will be attached 
> dynamically, and/or old
> screen for which we requested NSOpenGLPFAScreenMask will be detached.
> For example in the test case for this bug:
>  - If the screen via dock is attached before start of the app, we get 
> an exception because
>    we cannot initialize the "sharedContext".
>  - If the screen via dock is attached after start of the app, it 
> works, right?
Yes, since we do not have the required docked hardware, had to ask 
customer to test this and they confirm app does work if screen via dock 
is attached after they start the app.
> It looks like we "ignore" this attribute most of the time in the 
> multi-monitor config,
> probably we can drop if completely?
Modified webrev ignoring this NSOpenGLPFAScreenMask attribute. Normal 
working on primary display is not affected and I have given a fix to the 
customer to test in their environment and they confirmed it is working 
for them with external monitor.


>>> -phil.
>>> On 9/25/19, 3:49 AM, Prasanta Sadhukhan wrote:
>>>> Hi All,
>>>> Please review a fix for an issue where it is seen that if a 
>>>> MacBookPro is attached to an external monitor via dock and macbook 
>>>> lid is closed,
>>>> no Java swing applications will start.
>>>> It was found 
>>>> GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().getDefaultConfiguration() 
>>>> is returning null in this particular setup.
>>>> Since it was difficult to reproduce locally, enabling tracing 
>>>> reveals that CGLGraphicsConfig#getCGLConfigInfo() was failing in 
>>>> NSOpenGLPixelFormat.initWithAttributes()
>>>> Appkit documentation 
>>>> https://developer.apple.com/documentation/appkit/nsopenglpixelformat/1436219-initwithattributes?language=objc
>>>> says that it will return "|nil| if an object with the desired 
>>>> attributes could not be initialized".
>>>> Now, when the main display is closed, the
>>>> CGDisplayIDToOpenGLDisplayMask(displayID)
>>>> is returning 2 as glMask which when passed as an attribute to 
>>>> NSOpenGLPixelFormat, it fails to initialize.
>>>> Normally, with main Display being used, glMask is 1.
>>>> Proposed fix is to see if first initialization fails, then retry 
>>>> initialization without the offending glMask value for 
>>>> NSOpenGLPFAScreenMask attributes,
>>>> as documentation 
>>>> https://developer.apple.com/documentation/appkit/1436213-opengl_pixel_format_attributes/nsopenglpfascreenmask?language=objc
>>>> says "All screens specified in the bit mask are guaranteed to be 
>>>> supported by the pixel format.", so if it is not guranteed to be 
>>>> supported, initAttributes() might fail.
>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8223158
>>>> webrev: http://cr.openjdk.java.net/~psadhukhan/8223158/webrev.0/
>>>> Regards
>>>> Prasanta

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