On 05/12/2015 10:49 PM, Mandy Chung wrote:
But I think it should be pretty safe to make the java.util.Properties
object override all Hashtable methods and delegate to internal CMH so
that:
- all modification methods + all bulk read methods such as
(keySet().toArray, values.toArray) are made synchronized again
- individual entry read methods (get, containsKey, ...) are not
synchronized.
This way we get the benefits of non-synchronized read access but the
change is hardly observable. In particular since external
synchronization on the Properties object makes guarded code atomic
like it is now and individual entry read accesses are almost
equivalent whether they are synchronized or not and I would be
surprised if any code using Properties for the purpose they were
designed for worked any differently.
I agree that making read-only methods not synchronized while keeping
any method with write-access with synchronized is pretty safe change
and low compatibility risk. On the other hand, would most of the
overrridden methods be synchronized then?
Yes, and that doesn't seem to be a problem. Setting properties is not
very frequent operation and is usually quite localized. Reading
properties is, on the other hand, a very frequent operation dispersed
throughout the code (almost like logging) and therefore very prone to
deadlocks like the one in this issue. I think that by having an
unsynchronized get(Property), most problems with Properties will be
solved - deadlock and performance (scalability) related.
Regards, Peter
Mandy
