Native methods and virtual threads

[Brian S O'Neill]

In my project, I depend heavily on native methods which perform file 
I/O. These operations might block the current thread, but this isn't a 
concern, and in some cases, blocking is desirable. With virtual threads, 
I am concerned. I don't want to have to rewrite all my code to 
workaround any potential issues.

Inside the JDK, any calls which might block inside native code use the 
internal Blocker class to help ensure that virtual threads aren't 
starved of carrier threads. This class is internal, and I think it 
should stay that way. It's easy to be misused.

However, if it were possible to indicate that a downcall handle might 
block, it would be incredibly useful. This isn't likely to be misused 
simply because it wouldn't be applicable to ordinary code.