Java Virtual Thread
Coming to Java 19: Virtual threads and platform threads
virtual thread will mount on platform thread, to better exploit platform threads
when virtual thread is blocking, it will be unmounted from its carrier thread.
some times, virtual thread will pin or capture their carrier thread, in which won't be unmounted.
do not pool virtual thread, instead use semaphores to limit the number of virtual threads doing the same type task.
do not pin or capture their carrier thread. eg: Reentrant Locak instead of Syncronized
Reconsider the use of thread local variables, because virtual thread can be numerous.
virtual thread can support structured concurrency to avoid thread leak
Q: When virtual thread unmounted from carrier thread, where the stack frame will be store?
A: heap
Q: How JDK decides which virtual thread to mount ?
A: FIFO
深入理解Java虚拟机：JVM高级特性与最佳实践（第3版）12.4.1 线程的实现
Q: Why virtual thread is cheaper?
A: platform thread is 1:1 mapping to LWP(OS Thread), need more space, need switch between user space and kernel space. virtual thread is M:N(CORRECT ?) mapping to user thread, smaller and cut of lots of kernel operations.
Thread at OS level?
Thread at hardware level?
