Java应用程序服务器执行堆栈线程相似性

Question

Let's say we have Spring Boot application deployed under Tomcat or another app server.

Let's say the app is running and has some method execution stack. Is it possible execution stack can be transferred by App Server between threads within App Server built-in Thread Pool?

Ie can Thread Id will change within same execution stack of application (not internal app server stack)? Consider example:

class FooBar {

  fooBar() {
    foo()
    bar()
  }

  foo() {}

  bar() {}

}

Can it happen that App server will make method bar() run in Thread ID 1 and method foo() is run in Thread ID 2 when fooBar() started in Thread ID 1?

Warning: This is a tricky question and App servers do unexpected things which are contrary to the normal understanding of how JVM works.

Answer 1

No

It is impossible to change thread of running (or blocked) code.

PS: While app servers some time do tricky things they unable to brake JVM constraints (until they doesn't provide their own JVM with non standard behavior).