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Fri Mar 10 09:49:16 GMT 2017 Mapputall can cause ConcurrentModifcationException - http://cr.openjdk.java.net[..]ses/sun/management/Agent.java.sdiff.html Note on writing CopyOnWrite wrapper - http://flyingspaniel.blogspot.com[..]ot.com/2010/12/copyonwrite-wrappers.html Sometime this is a bit difficult for Chinese to be a good programmer, recently some colleague and me discuss about the behaviour of this class and look like we have difficult understanding A: ConcurrentHashMap support for locking as this is thread-safe B: ConcurrentHashMap is thread safe for read but not for write because there is no lock, we still need to have external lock to keep it thread safe. By the way, I get ConcurrentModificationException from this before. C: ConcurrentHashMap don't support for locking but they still thread safe for all operations, which is how "This class is fully interoperable with Hashtable in programs that rely on its thread safety but not on its synchronization details." mentioned. Too good that we can actually take a look at the source code to see what going on nowadays rather than just guessing - http://www.google.com[..]HashMap&sourceid=opera&ie=utf-8&oe=utf-8 By the way, this constructor is useful for a lot of concurrency access but actually not many developer notice about this - http://java.sun.com[..]rrentHashMap.html#ConcurrentHashMap(int, float, int) Lazy initialization of map values - http://artisans-serverintellect-com.si-eioswww6.com[..]ect-com.si-eioswww6.com/default.asp?W122 HashMap.get() can cause infinite loop - http://lightbody.net[..]5/07/hashmapget_can_cause_an_infini.html Discussing the effect of initCapacity() of HashMap in Java - http://saloon.javaranch.com[..]ltimatebb.cgi?ubb=get_topic&f=1&t=021171 OpenJDK and HashMap …. Safely Teaching an Old Dog New (Off-Heap!) Tricks - http://www.infoq.com/articles/Open-JDK-and-HashMap-Off-Heap We can run search in ConcurrenctHashMap - https://dzone.com/articles/concurrenthashmap-in-java8 (google search) (amazon search) second |