why using volatile with synchronized block?

why using volatile with synchronized block?

java multithreading volatile synchronized double-checked-locking

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Double-checked locking in .NET

.net multithreading paradigms double-checked-locking

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Java double checked locking

java multithreading synchronization singleton double-checked-locking

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Double-checked locking without volatile

java multithreading final java-memory-model double-checked-locking

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Threadsafe lazy initialization: static vs std::call_once vs double checked locking

c++ multithreading c++11 double-checked-locking

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Lazily initialize a Java map in a thread safe manner

java multithreading dictionary double-checked-locking

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Double checked locking on Dictionary "ContainsKey"

c# multithreading collections dictionary double-checked-locking

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How to show that the double-checked-lock pattern with Dictionary's TryGetValue is not threadsafe

c# .net multithreading double-checked-locking

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double checked locking pattern

c++ multithreading double-checked-locking

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Double-Checked Locking Pattern in C++11?

multithreading c++11 singleton double-checked-locking

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Synchronization in a HashMap cache

java multithreading caching synchronization double-checked-locking

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