Singleton
Synchronized Pattern
⛔Since the read of instance
is synchronized => it cannot be made in parallel => in multicore world this is already a bad (non-performant) implementation of Singleton
Double check locking Singleton pattern
⛔There is a bug in this implementation
in (1) the read is not synchronized or volatile =>
non synchronized read
in (2) the write is synchronized =>
synchronized write
Do we have a guarantee that the read will get the value set by write?
⚠️for this we need
happens before link
⚠️But the fix by making an instance volatile
costs the same performance prise as in synchronized
Pattern above.
Enum solution
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