Java ConcurrentMap
part 5/19 · 30.6 KB total
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In order to help with the concurrent modification problem, the non-concurrent Map implementations and other Collections use internal modification counters which are consulted before and after a read to watch for changes: the writers increment the modification counters. A concurrent modification is supposed to be detected by this mechanism, throwing a java.util.ConcurrentModificationException,cite-ref-footnotegoetzpeierlsblochbowbeer200682-83-5-1-2-iterators-and-concurrentmodificationexception-3-0[3] but it is not guaranteed to occur in all cases and should not be relied on. The counter maintenance is also a performance reducer. For performance reasons, the counters are not volatile, so it is not guaranteed that changes to them will be propagated between Threads.
Collections.synchronizedMap()