Исправление Midael, (текущая версия) :
А это что?
The vast majority of blocking operations in the JDK will unmount the virtual thread, freeing its carrier and the underlying OS thread to take on new work. However, some blocking operations in the JDK do not unmount the virtual thread, and thus block both its carrier and the underlying OS thread.
...
There are two scenarios in which a virtual thread cannot be unmounted during blocking operations because it is pinned to its carrier:
1) When it executes code inside a synchronized block or method, or
2) When it executes a native method or a foreign function.
Pinning does not make an application incorrect, but it might hinder its scalability. If a virtual thread performs a blocking operation such as I/O or BlockingQueue.take() while it is pinned, then its carrier and the underlying OS thread are blocked for the duration of the operation. Frequent pinning for long durations can harm the scalability of an application by capturing carriers.
...
In a future release we may be able to remove the first limitation above, namely pinning inside synchronized. The second limitation is required for proper interaction with native code.
(c) https://openjdk.org/jeps/444
https://cr.openjdk.org/~rpressler/loom/loom/sol1_part1.html#pinning
Исходная версия Midael, :
А это что?
The vast majority of blocking operations in the JDK will unmount the virtual thread, freeing its carrier and the underlying OS thread to take on new work. However, some blocking operations in the JDK do not unmount the virtual thread, and thus block both its carrier and the underlying OS thread. ... There are two scenarios in which a virtual thread cannot be unmounted during blocking operations because it is pinned to its carrier:
When it executes code inside a synchronized block or method, or When it executes a native method or a foreign function. Pinning does not make an application incorrect, but it might hinder its scalability. If a virtual thread performs a blocking operation such as I/O or BlockingQueue.take() while it is pinned, then its carrier and the underlying OS thread are blocked for the duration of the operation. Frequent pinning for long durations can harm the scalability of an application by capturing carriers. ... In a future release we may be able to remove the first limitation above, namely pinning inside synchronized. The second limitation is required for proper interaction with native code.
(c) https://openjdk.org/jeps/444
https://cr.openjdk.org/~rpressler/loom/loom/sol1_part1.html#pinning