RFR(M): JDK-8203321: Windows: assert(current_query_index < process_query_set->size) failed: invariant

[coleen.phillimore at oracle.com]

Hi, Maybe this should go on serviceability-dev as well.
Thanks,
Coleen

On 5/22/18 3:24 PM, Markus Gronlund wrote:
> Greetings,
>
> Kindly asking for reviews for the following change:
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8203321
> Webrev: http://cr.openjdk.java.net/~mgronlun/8203321/webrev00/
>
> Summary:
>
> For some context about what this is about, please see this (now) relatively old issue: https://bugs.openjdk.java.net/browse/JDK-8019921
>
> The porting work that brought this code from closed to open were optimistic in that the following PDH query,  "\Process(java#n)\ID Process", performed relatively stable on Windows 10.
> An invariant was added in that your ID Process query would never return an index that was lower than the index at construction.
>
> During testing, it was discovered that this invariant did not hold, especially when running on Windows Server 2012 R2 and there is a high churn rate with many processes with the same base name ("java#") starting and stopping (stressing PDH list of processes).
>
> We have to reinsert back the original code that handled the case where the PDH process list is not stable (that were originally put in place with JDK-8019921).
> The defensive logic is located at lines 418 - 422.
>
> I had to rework some related code to make some room for this as well as to keep track of the previous process index.
>
> Thanks
> Markus