RFR: 8210889: Some service thread cleanups can be starved

[Kim Barrett]

> On Sep 19, 2018, at 3:32 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> 
> Hi,
> 
> On Tue, 2018-09-18 at 20:46 -0400, Kim Barrett wrote:
>> Please review this small change to the ServiceThread.  When checking
>> for work to be done, rather than immediately doing the first kind of
>> work found, instead determine all pending work and then do all known
>> pending work.  This avoids the possibility of frequently available
>> work early in the sequence of checks from leading to starvation of
>> work associated with later checks.
> 
> Looks good. Maybe the comment could be improved because it does not
> answer why we do not want short-circuiting in this case. It only seems
> to describe what the code does.
> 
> Thanks,
>  Thomas

Sure, I can do that:

      // Process all available work on each (outer) iteration, rather than
      // only the first recognized bit of work, to avoid frequently true early
      // tests from potentially starving later work.  Hence the use of
      // arithmetic-or to combine results; we don't want short-circuiting.

Thanks for reviewing.