[8u] RFR for JDK-8154324: Request to backport JDK-6515172 to 8u

[David Holmes]

Hi Shafi,

On 9/09/2016 3:46 PM, Shafi Ahmad wrote:
> Hi,
>
> Please review the backport [modified] of bug: "JDK-6515172 Runtime.availableProcessors() ignores Linux taskset command" to jdk8u.
>
> Please note that the backport is not clean and we can't do as it is. Please note
>   1. The changes are made by 'Andreas Eriksson' who left Oracle.
>   2. There is difference in logging mechanism in jdk9 and jdk8 is different and file logTag.hpp doesn't exists in jdk8.
>   3. Newly added test pass after this change. It fails without this change.
>
> Webrev link: http://cr.openjdk.java.net/~shshahma/8154324/webrev.00/
> Jdk9 bug: https://bugs.openjdk.java.net/browse/JDK-6515172
> Jdk8 bug: https://bugs.openjdk.java.net/browse/JDK-8154324
> Original patch pushed to jdk9: http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/c5480d4abfe4

I worked extensively with Andreas on this as there were a number of 
issues. I'll have to try and find those discussions to see where we 
ended up.

The backport as stands is not quite appropriate. For example it adds:

diagnostic(bool, UseCpuAllocPath, false,

but that does not exist in the actual code for 8.

Also this comment:

+ // If it appears there may be more than 1024 processors then we do a
+ // dynamic check - see 6515172 for details.

is wrong as there is no dynamic check in this version of the code.

The last I recall with this is that there were issues caused by building 
with one version of glibc and running (or trying to) on later versions 
of glibc. But as I said I will have to see if I have the discussion from 
that effort.

David
----

> Testing: jprt and running jtreg.
>
> Regards,
> Shafi
>