[concurrency-interest] volatile guarantee for directbuffer
nathan.reynolds at oracle.com
Tue Feb 14 16:58:36 EST 2012
Yes, all stores preceeding a volatile store will be visible. It doesn't
matter if this store is on Java heap, off Java heap or else where. On
x86, the JVM puts in a fence after the volatile store. This fence
applies to all memory accesses regardless of where they are located.
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On 2/14/2012 1:25 PM, Talip Ozturk wrote:
>> I'm not sure what you mean be OffHeap, but actually that doesn't matter
>> at all: Writing to a volatile will make _all_ writes that happened
>> earlier in the same thread visible to all threads, no matter what
>> and where that earlier-written data is. (I use to tell my students
>> "writing to a volatile flushes the cache".)
> Main question wasn't about guarantees of volatiles at all. We can use
> volatile variables to guarantee 'happens-before' for the data we have
> on-heap. Does it give the same guarantees for the the data stored
> off-heap. DirectByteBuffer would be a good example of off-heap data.
> I at least got one answer saying 'yes' to my question.
> Concurrency-interest mailing list
> Concurrency-interest at cs.oswego.edu
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