The I/O Poller used to support virtual threads doing blocking networking I/O has been significantly refactored in the loom repo. There are several improvements that should be brought to main line:

1. New poller poll that uses a read poller per carrier, this is beneficial in some workloads.
2. Better cleanup/recovery in the event if a file descriptor or memory can't be allocated during initializatio.
3. NativeThread changed to cache native thread ID and avoid JNI call to current0 for each blocking I/O op.