Code generated by Java synchronized function

Question

I don't really see the difference of execution between

public void foo_fct( Table Tbl, Account act)
{
  synchronized(Tbl) {
    ...
  }
}

and this :

public void foo_fct( Table Tbl, Account act)
{
  synchronized(act) {
    ...
  }
}

I mean, under the hood, the JVM must use lock() and unlock() I guess? So whatever it happens (act or Tbl) I will be locking in the same way no ?

update Ok, I understand now with your help and Java doc :

"...Every object has an intrinsic lock associated with it..."

and "synchronized statements..."

docs.oracle.com/javase/tutorial/essential/concurrency/… should be a place to start for this. — user1531971
– user1531971, Commented Jan 14, 2015 at 15:05

vikingsteve · Accepted Answer · 2015-01-14 15:06:57Z

1

Yes, there is a difference, since you never know which other threads are using sychronized on the Table or the Account.

Ask yourself the question- are you trying to prevent other mutable operations on the Table or the Account for the duration of execution of the sychronized block in foo_fct method?

answered Jan 14, 2015 at 15:06

vikingsteve

40.7k25 gold badges120 silver badges164 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Valentin Ruano · Accepted Answer · 2015-01-14 15:20:16Z

0

If table and accounts are organized in fixed exclusive pairs meaning no foo_fct on a table x will be called with different account instances by different concurrent threads (and vice versa) and there no other parts of the code that make other synchronized operations on tables or accounts in your program concurrently then both ways to lock are equivalent.

Otherwise both approaches would be different.

answered Jan 14, 2015 at 15:20

Valentin Ruano

2,83920 silver badges31 bronze badges

Comments

tmarwen · Accepted Answer · 2015-01-14 15:12:27Z

0

The synchronized(var) block will make difference based on the ... block that you omitted, i.e. on which variable you already need to synchronize concurrent threads access.

answered Jan 14, 2015 at 15:12

tmarwen

16.5k5 gold badges48 silver badges65 bronze badges

Collectives™ on Stack Overflow

Code generated by Java synchronized function

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related