[OpenJDK 2D-Dev] Thread safety of SunFontManager.platformFontMap

[Philip Race]

The map is not expected to be updated after it has been created so it 
should not need synchronized access.
There are a couple of exceptions where it is being updated when some 
file that
is supposed to be there can't be found - a scenario that apparently 
hasn't been
an issue in the 10 years this code has been in use.
So the removal is an optimisation that could be revisited.

-phil.

On 2/22/21 4:40 AM, Andrey Turbanov wrote:
>
> Hello.
> I recently found suspicious field (with SpotBugs help) in class 
> SunFontManager:
>
>     static HashMap<String, FamilyDescription> platformFontMap;
>
> This HashMap is accessed (read and write) in a method
> sun.font.SunFontManager#findFontFromPlatformMap. As I see there is no
> synchronization when this HashMap is accessed.
> This method can be called from client code with this simple stack trace:
>
>       at 
> sun.font.SunFontManager.findFontFromPlatformMap(SunFontManager.java:1508)
>       at sun.font.SunFontManager.findFont2D(SunFontManager.java:2069)
>       at java.awt.Font.getFont2D(Font.java:500)
>       at java.awt.Font.getPSName(Font.java:1416)
>
> I wonder if this unsynchronized access is expected. Looks like it can
> break things when accessed from multiple threads simultaneously.
> Do I miss something? Is it done this way, because Font objects are
> supposed to be accessed from a single thread only?
>
> Andrey Turbanov

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