🚀 go-pugleaf

Followup question to your examples:

Are you saying that this code snippet:

> public synchronized void setTemp2(int temp2) {this.temp2 = temp2;}
> or
> public void setTemp2(int temp2) { synchronized {this.temp2 = temp2;}}
>
> with
>
>    public int performCalculation(int x, int y) {
>      int temp1 = 0;
>      temp1 = y + 5;
> synchronized
> {
>      temp2 = x / 3;
>      return temp1 + temp2;
> }
>    }

is equivalent to this code snippet:

> Also
>  public int performCalculation(int x, int y) {
>      int temp1 = 0;
>      temp1 = y + 5;
> synchronized(temp2)
> {
>      temp2 = x / 3;
>      return temp1 + temp2;
> }
>    }

In the first example you have 2 sets of synchronized block. In the second
you have just one synchronized block, but referring to the temp2 variable.
I'm reading this as meaning if I write synchronized(temp2){} that I don't
need to put synchronized in setTemp2. Was that your intent?

-zoltan


"dnoyeB" <lamont_gilbert @ rigidsoftware.com> wrote in message
news:3b3110f0$3_1@dnews...
> No that is not a sufficient solution.  Synchronized just means 2 threads
> cant call that code at the same time.  However, you failed to synchronize
> the method below.  Remember, you are synchronizing with respect to temp2
> actually.
>
> public void setTemp2(int temp2) {this.temp2 = temp2;}
>
> AS a result it can be called anytime, even while another thread is in the
> synchronized section you created below
>
> >     synchronized {
> >       temp2 = x / 3;
> >       return temp1 + temp2;
> >     }
>
>
> In otherwords, 2 threads cant enter the synchronized section you created
> which does add necessary safety, but 1 thread could be in that section,
> while another is calling setTemp2, which would again be thread unsafe.
>
> better is
>
> public synchronized void setTemp2(int temp2) {this.temp2 = temp2;}
> or
> public void setTemp2(int temp2) { synchronized {this.temp2 = temp2;}}
>
> with
>
>    public int performCalculation(int x, int y) {
>      int temp1 = 0;
>      temp1 = y + 5;
> synchronized
> {
>      temp2 = x / 3;
>      return temp1 + temp2;
> }
>    }
>
>
> Also
>  public int performCalculation(int x, int y) {
>      int temp1 = 0;
>      temp1 = y + 5;
> synchronized(temp2)
> {
>      temp2 = x / 3;
>      return temp1 + temp2;
> }
>    }
>
> good luck
>
>
>
>
> Synchronizing is taxing.  Try not to synchronize in loops whenever
> possible!!
>
> "Zoltan Grose" <zgrose@pacbell.net> wrote in message
> news:3b1b28df$1_2@dnews...
> > I'm going to be diving into servlet programming shortly and I feel now
is
> a
> > good time to wrap my brain around threads and the keyword synchronized.
> >
> > From the reading I have done and the examples I have seen, I believe I
can
> > summarize the use of synchronized in this way:
> >
> > "If a method accesses (either reads from or writes to) a variable that
one
> > reasonably expects not be constant and that variable is not local to the
> > method, the accessing code should be synchronized."
> >
> > For example, I believe this code to be thread-safe since all of the
> > variables are local.
> >
> > public class MyClass {
> >   public int performCalculation(int x, int y) {
> >     int temp1 = 0; int temp2 = 0;
> >     temp1 = y + 5;
> >     temp2 = x / 3;
> >     return temp1 + temp2;
> >   }
> > }
> >
> > I believe this code to be thread-unsafe since temp2 is not local to the
> > method and could potential be modified at any point during any execution
> of
> > performCalculation.
> >
> > public class MyClass {
> >   int temp2 = 0;
> >   public void setTemp2(int temp2) {this.temp2 = temp2;}
> >   public int performCalculation(int x, int y) {
> >     int temp1 = 0;
> >     temp1 = y + 5;
> >     temp2 = x / 3;
> >     return temp1 + temp2;
> >   }
> > }
> >
> > The second example would be made thread-safe again by wrapping the
unsafe
> > section in a sychronized block.
> >
> >     synchronized {
> >       temp2 = x / 3;
> >       return temp1 + temp2;
> >     }
> >
> > Am I on the right track? (Am I in the right newsgroup?) My background is
> in
> > VB, so threads are one of the new concepts I'm trying to deal with
before
> I
> > get to deep. Thanks in advance.
> >
> > -zoltan
> >
> >
> >
>
>