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 <ralph.go...@dslextreme.com> 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 <boa...@gmail.com> 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 <ralph.go...@dslextreme.com> 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 <boa...@gmail.com> 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 <garydgreg...@gmail.com> 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 <ralph.go...@dslextreme.com >>> > 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<http://www.manning.com/bauer3/> >>> JUnit in Action, Second Edition <http://www.manning.com/tahchiev/> >>> Spring Batch in Action <http://www.manning.com/templier/> >>> Blog: http://garygregory.wordpress.com >>> Home: http://garygregory.com/ >>> Tweet! http://twitter.com/GaryGregory >>> >> >> >> >> -- >> Matt Sicker <boa...@gmail.com> >> >> >> > > > -- > Matt Sicker <boa...@gmail.com> > > > -- Matt Sicker <boa...@gmail.com>
