RFR(S): 8034839: jvm hangs with gc/gctests/LoadUnloadGC test
albert.noll at oracle.com
Fri Feb 21 00:04:55 PST 2014
could I get reviews for this small patch?
Problem: The problem is that the patch (7194669) - which was supposed to
speed-up dependency checking
causes a performance regression. The reason for the
performance regression is that most dependencies
are unique, so we have the overhead of determining if
the dependency is already checked plus the
overhead of dependency checking. The overhead of
searching is significant, since we perform
a linear search on 6000+ items each time.
Solution: Use a hashtable instead of linear search to lookup already
checked dependencies. The new hashtable
is very rudimentary. It provides only the required
functionality to solve this bug. However, the functionality
can be easily extended as needed.
Testing: jprt, failing test case, nashorn. The failing test case
completes in approx. the same time as before 7194669.
For nashorn + Octane, this patch yields the following
times spent for dependency checking:
with this patch: 844s
before 7194669: 5223s
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