Re: Concurrency question?
On 01/31/2015 12:42 PM, Eric Sosman wrote:
On 1/31/2015 2:20 PM, Volker Borchert wrote:
Knute Johnson wrote:
So I have a Map<Integer,String> [ ... ]
Do you see any holes in my logic? Any suggestions?
java.util.concurrent.ConcurrentHashMap<K,V>
That's fine if the consistency criterion involves only single
mappings. But if different mappings within the same Map must "agree"
(in some application-dependent sense), atomicity of individual updates
isn't good enough.
Only Knute knows for sure ...
When I first saw Volker's suggestion I thought, no I can't iterate over
the map without some other synchronization but I looked into the
ConcurrentHashMap docs and found;
"Similarly, Iterators, Spliterators and Enumerations return elements
reflecting the state of the hash table at some point at or since the
creation of the iterator/enumeration. They do not throw
ConcurrentModificationException. However, iterators are designed to be
used by only one thread at a time."
As subtle as his suggestion was, I think he may be on to something. I'm
going to think about it some more but Volker may have the simplest solution.
--
Knute Johnson