RFR: 8260366: ExtendedSocketOptions <clinit> can deadlock in some circumstances [v2]

[Jaikiran Pai]

On Thu, 18 Feb 2021 07:59:45 GMT, Andrey Turbanov <github.com+741251+turbanoff at openjdk.org> wrote:

>> Hello @turbanoff, the double read is necessary to correctly avoid any race conditions and is a typical strategy used in cases like these. I am not aware of any other alternate more performant strategy, for code like this.
>
> Let me be more clear: I think that it's enough to have only 2 `volatile` field reads _in worst case_. We can use local variable to avoid more than needed reads.
> Current code can perform read 4 times _in worst case_: twice outside `synchronized` block and twice inside `synchronized` block.
> 
> There are many examples of similar code in the JDK:
> https://github.com/openjdk/jdk/blob/master/src/jdk.crypto.cryptoki/share/classes/sun/security/pkcs11/P11Util.java#L48
> https://github.com/openjdk/jdk/blob/master/src/java.base/share/classes/java/lang/StackFrameInfo.java#L125

Ah! of course, I now see what you mean. I misunderstood your previous comment. I'll update this PR shortly.

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PR: https://git.openjdk.java.net/jdk/pull/2601