[logback-dev] synchronization style?

[Ralph Goers]

I would recommend the second, largely because some of the things that  
are being synchronized might be able to be converted to constructs  
that don't require synchronization. Furthermore, as long as you are  
holding a lock over such a wide scope you run the risk of something  
being inserted into that synchronized block that does something that  
raises the possibility of a deadlock.

I would comment more but my wife is in the hospital for the next few  
days so I won't have much time until after the weekend.

Ralph

On Jul 2, 2009, at 12:39 AM, Ceki Gulcu wrote:

>
> Hello,
>
> I am hesitating between the two following styles of synchronization.
>
> First style, with one lengthy synchronization block
>
> synchronize(x) {
>  shortOpA();
>  shortOpB();
>  shortOpC();
>  shortOpD();
>  longOp();
> }
>
> Second style, with  shorter but more numerous synchronization blocks
>
> synchronize(a) {
>  shortOpA();
> }
>
> synchronize(b) {
>  shortOpB();
> }
>
> shortOpC(); // no need for synchronization
> shortOpD(); // no need for synchronization
>
> synchronize(x) {
>  longOp();
> }
>
>
> Let us assume that longOp() takes about 5 times longer than
> shortOp_N() to complete. Moreover, all operations are self contained,
> with no further synchronization (locking) dependencies to external
> code.
>
> I wonder which style is better. The first style is simpler to
> understand, because there is just one synchronization block. However,
> the monitor is held for a longer period. In the second style, there
> are more locks, so the code may be harder to follow but each lock is
> held for a shorter period.
>
> Surprisingly enough, tests (with 10 threads) show that performance is
> slightly better with the first style.
>
> Am I splitting hairs?
>
> -- 
> Ceki Gülcü
> Logback: The reliable, generic, fast and flexible logging framework  
> for Java.
> http://logback.qos.ch
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