RFR (S): 8206453: Taskqueue stats should count real steal attempts, not calls to GenericTaskQueueSet::steal

[Thomas Schatzl]

Hi all,

  can I have reviews for some small change to how successful steals and
steal attempts in taskqueue statistics are gathered? In particular, as
the subject of the CR suggests, the "steal attempts" counter the number
of calls to GenericTaskQueueSet::steal() which internally actually
attempts stealing quite often.

This makes a useful comparison of steal attempts to successful steals
impossible and misleading.

The calls to GenericTaskQueueSet::steal are mostly reflected to the
number of termination attempts that is already counted elsewhere (ie.
steal attempts - successful steals), so it does not really give new
information.

CR:
https://bugs.openjdk.java.net/browse/JDK-8206453
Webrev:
http://cr.openjdk.java.net/~tschatzl/8206453/webrev/
Testing:
local compilation and use with and without TASKQUEUE_STATS.

Thanks,
  Thomas