Please keep in mind that synchronized is not fair. http://sourceforge.net/apps/trac/lilith/wiki/SynchronizedVsFairLock
Yes, a fair ReentrantLock is way slower than an unfair one… but if starvation is caused by a logging framework then this is a serious issue in my opinion. Joern On 29. April 2014 at 01:05:26, Matt Sicker (boa...@gmail.com) wrote: > I'll delegate my arguments to the SO post about it: > http://stackoverflow.com/questions/442564/avoid-synchronizedthis-in-java > > In short, it's defensive programming. It's safer to synchronize on an > internal object than on this. Plus, it aids in concurrency throughput > instead of just using a synchronized method. > > > On 28 April 2014 12:45, Ralph Goers wrote: > > > Why are they not appropriate lock objects? Start a discussion before just > > changing them. > > > > Ralph > > > > > > > > On Apr 28, 2014, at 10:40 AM, Matt Sicker wrote: > > > > In that case, Item 69: prefer concurrency utilities to wait and notify. > > Sounds like we can just use a plain Object instance to lock (which is > > pretty much equivalent to using ReentrantLock) when doing normal locks, but > > instead of using .notifyAll() and .wait(), we should use the Condition > > interface (which would require using Lock as well). > > > > I agree that using synchronized(object) makes sense when it's all that's > > being done. However, I've been changing instances of synchronized(this) and > > synchronized(foo) where foo is not an appropriate lock object (e.g., a > > string, or a non-final object, things like that). > > > > > > On 28 April 2014 12:28, Ralph Goers wrote: > > > >> Yes, guidelines called out by Effective Java are appropriate when they > >> apply. > >> > >> As for concurrency, “New” isn’t always better than old. In a few places > >> you changed synchronized(object) to use a Lock instead. There is little to > >> no value in doing that and makes the code look a little more cluttered. > >> However, if a ReadWriteLock can be used in place of synchronized that is a > >> real benefit. > >> > >> The point of the guidelines are that when it comes to stuff like this, > >> unless there is a guideline written down that says the current code is > >> wrong discuss it on the list before making a change. > >> > >> Ralph > >> > >> On Apr 28, 2014, at 9:35 AM, Matt Sicker wrote: > >> > >> What about style things covered by Effective Java? These are pretty much > >> all good ideas. > >> > >> Also, how about some guidelines on concurrency? I'd recommend not using > >> the old concurrency stuff and instead using java.util.concurrent.* for more > >> effective concurrency. This doesn't include the Thread vs Runnable thing, > >> so that's still debatable. > >> > >> > >> On 28 April 2014 08:46, Gary Gregory wrote: > >> > >>> Perhaps if one breaks the build, it should be polite to revert that last > >>> commit... > >>> > >>> Gary > >>> > >>> > >>> On Mon, Apr 28, 2014 at 3:07 AM, Ralph Goers > >>> > wrote: > >>> > >>>> I think we need to develop and post some development “guidelines”, > >>>> “best practices” or whatever you want to call it for Log4j 2. Here are > >>>> some of the things I would definitely want on it. > >>>> > >>>> 1. Error on the side of caution. If you don’t understand it, don’t > >>>> touch it and ask on the list. If you think you understand it read it > >>>> again > >>>> or ask until you are sure you do. Nobody will blame you for asking > >>>> questions. > >>>> 2. Don’t break the build - if there is the slightest chance the change > >>>> you are making could cause unit test failures, run all unit tests. Better > >>>> yet, get in the habit of always running the unit tests before doing the > >>>> commit. > >>>> 3. If the build breaks and you have made recent changes then assume you > >>>> broke it and try to fix it. Although it might not have been something you > >>>> did it will make others feel a lot better than having to fix the mistake > >>>> for you. Everyone makes mistakes. Taking responsibility for them is a > >>>> good > >>>> thing. > >>>> 4. Don’t change things to match your personal preference - the project > >>>> has style guidelines that are validated with checkstyle, PMD, and other > >>>> tools. If you aren’t fixing a bug, fixing a problem identified by the > >>>> tools, or fixing something specifically called out in these guidelines > >>>> then > >>>> start a discussion to see if the change is something the project wants > >>>> before starting to work on it. We try to discuss things first and then > >>>> implement the consensus reached in the discussion. > >>>> > >>>> Of course, the actual coding conventions we follow should also be > >>>> spelled out, such as indentation, braces style, import ordering and where > >>>> to use the final keyword. > >>>> > >>>> Ralph > >>>> --------------------------------------------------------------------- > >>>> To unsubscribe, e-mail: log4j-dev-unsubscr...@logging.apache.org > >>>> For additional commands, e-mail: log4j-dev-h...@logging.apache.org > >>>> > >>>> > >>> > >>> > >>> -- > >>> E-Mail: garydgreg...@gmail.com | ggreg...@apache.org > >>> Java Persistence with Hibernate, Second Edition > >>> JUnit in Action, Second Edition > >>> Spring Batch in Action > >>> Blog: http://garygregory.wordpress.com > >>> Home: http://garygregory.com/ > >>> Tweet! http://twitter.com/GaryGregory > >>> > >> > >> > >> > >> -- > >> Matt Sicker > >> > >> > >> > > > > > > -- > > Matt Sicker > > > > > > > > > -- > Matt Sicker > --------------------------------------------------------------------- To unsubscribe, e-mail: log4j-dev-unsubscr...@logging.apache.org For additional commands, e-mail: log4j-dev-h...@logging.apache.org
