tipsmart mock question

[Shiva Mohan]

State which of the following statements are True.

(1) Concurrent Java programs can exhibit deterministic behavior, by providing mechanisms for synchronizing.
(2) Threads have parent-child relationships.
(3) When the thread is created, it is not yet active

a. 1 and 3
b. All 3
c. 1 and 2

The given answer is a.but why 2 is not included.Please i am looking for the rules?Option 1 expalnation too.

[Andrea Z�rcher]

Hi Shiva

1) Is true. When multi-threaded code isn�t correctly synchronised, non-deterministic and unexpected behaviour can occur.

2) Is false, because as far as I know only processes in the system have parent-child relationship. A thread is a single sequential flow of control within a process (also named lightweight process). Threads in a process have no parent-child relationship with each other.

3) is true (I think �active� means �running�). A call to start() will not immediately start thread's execution. It will move it to the ready-to-run pool. Based on the thread priorities, the thread scheduler will pick one of the ready-to-run threads and the thread will enter the running-state.

Hope I�m right and this explanation will help you.

Andrea

[marc weber]

Originally posted by Andrea Z�rcher:
...1) Is true. When multi-threaded code isn�t correctly synchronised, non-deterministic and unexpected behaviour can occur...

Yes, but I think the question is how synchronization might change this.

When multiple Java threads are running, it's up to the thread scheduler to determine when each thread will get a chance to run. This can result in somewhat unpredictable behavior. Synchronized code requires a thread to get the lock before proceeding, so this can force threads to wait if another thread has the lock.

[Shiva Mohan]

Thanks for the detailed explanation Andrea and marc.