Threads

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 Threads

Can anyone please explain the difference between the two types: green threads

and native threads?

Answer: Green threads is thread mechanism implemented in JVM itself. 

It is blind and can run on any OS, so actually all threads are run in one 

native thread and scheduling is up to JVM. This is disadvantageously for 

SMP systems, since only one processor can serve Java application.

Native threads is a mechanism based on OS threading mechanism. This allows 

to use features of hardware and OS. For example,there is IBM s JDK for 

AIX that supports native threads. The perfomance of applications 

can be highly imploved by this.

 Q: If a thread object has quit from run loop, how can I restart the thread object? (

I don t want to use some flags with wait/notify method to simulate restarting).

I try to use start() method, but it doesn t work.

Answer: No   Threads can t be restarted. You have to either loop with a wait/notify or

create a new Thread.

J. Skeet

I m having trouble getting sleep to work properly. It seems to just return

immediately, and not sleep for the requested time. Is there some trick I need to know

about? The docs say that sleep takes an argument in milli seconds, but sleep(10000)

seems to return immediately.

Answer:  It can happen if another thread interrupts your sleeping thread. 

sleep(10000) says that it just can sleep 10 sec if nobody needs it. That is reason why

you do

try{     

    sleep(10000);

}

catch(InterruptedException x){

    //do smth here

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