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It is important to note that neither Thread.sleep nor Thread.yield have any synchronization semantics. In particular, the compiler does not have to flush writes cached in registers out to shared memory before a call to Thread.sleep or Thread.yield, nor does the compiler have to reload values cached in registers after a call to Thread.sleep or Thread.yield.

Code that depends bases its concurrency safety on thread suspension or that yields to processes that

• flush cached registers
• reload any values
• provide any happens-before relationships when execution resumes

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