Proposal for adding O_DIRECT support into JDK 9

Lu, Yingqi at
Tue Sep 27 16:57:06 UTC 2016


Thank you for the explanation, we will modify the code accordingly and send it out soon for review.


-----Original Message-----
From: Alan Bateman [mailto:Alan.Bateman at] 
Sent: Tuesday, September 27, 2016 8:45 AM
To: Lu, Yingqi < at>; core-libs-dev at
Cc: nio-dev at
Subject: Re: Proposal for adding O_DIRECT support into JDK 9

On 26/09/2016 19:50, Lu, Yingqi wrote:

> Alan, you mean readv0/write0 or read0/write0? I just want to make sure 
> :-)
Apologies, I meant each of the native methods where the decision to use direct I/O or not would be a lot more maintainable in Java. You'll see that there are already code paths for direct vs. heap buffers.

> Anyone else has other opinions on where is the best home for O_DIRECT flag? The flags under jdk.unsupported will eventually be removed in the future JDK release?
> If we agree ExtendedOpenOpen is the best home for O_DIRECT, we can modify that for sure.
I think ExtendedOpenOption is the right place. It's still TDB as to whether to put these extensions but that should be transparent to anyone using this when on the class path.


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