Back after a long hiatus... Thanks, Eric, for your review. Here's a new webrev incorporating your recommendations.
Bug: https://bugs.openjdk.java.net/browse/JDK-8195115 Webrev: http://cr.openjdk.java.net/~phh/8195115/webrev.02/ TIA for your re-review. Plus, may I have another reviewer look at it please? Paul On 2/26/18, 8:47 AM, "Erik Helin" <erik.he...@oracle.com> wrote: Hi Paul, a couple of comments on the patch: - memoryService.hpp: + 150 bool countCollection, + 151 bool allMemoryPoolsAffected = true); There is no need to use a default value for the parameter allMemoryPoolsAffected here. Skipping the default value also allows you to put allMemoryPoolsAffected to TraceMemoryManager::initialize in the same relative position as for the constructor parameter (this will make the code more uniform and easier to follow). - memoryManager.cpp Instead of adding a default parameter, maybe add a new method? Something like GCMemoryManager::add_not_always_affected_pool() (I couldn't come up with a shorter name at the moment). - TestMixedOldGenCollectionUsage.java The test is too strict about how and when collections should occur. Tests written this way often become very brittle, they might e.g. fail to finish a concurrent mark on time on a very slow, single core, machine. It is better to either force collections by using the WhiteBox API or make the test more lenient. Thanks, Erik On 02/22/2018 09:54 PM, Hohensee, Paul wrote: > Ping for a review please. > > Thanks, > > Paul > > On 2/16/18, 12:26 PM, "serviceability-dev on behalf of Hohensee, Paul" <serviceability-dev-boun...@openjdk.java.net on behalf of hohen...@amazon.com> wrote: > > The CSR https://bugs.openjdk.java.net/browse/JDK-8196719 for the original fix has been approved, so I’m back to requesting a code review, please. > > Bug: https://bugs.openjdk.java.net/browse/JDK-8195115 > Webrev: http://cr.openjdk.java.net/~phh/8195115/webrev.hs.01/ > > Passed a submit repo run, passes its jtreg test, and a JDK8 version is in production use at Amazon. > > From the original RR: > > > The bug is that from the JMX point of view, G1’s incremental collector > > (misnamed as the “G1 Young Generation” collector) only affects G1’s > > survivor and eden spaces. In fact, mixed collections run by this > > collector also affect the G1 old generation. > > > > This proposed fix is to record, for each of a JMX garbage collector's > > memory pools, whether that memory pool is affected by all collections > > using that collector. And, for each collection, record whether or not > > all the collector's memory pools are affected. After each collection, > > for each memory pool, if either all the collector's memory pools were > > affected or the memory pool is affected for all collections, record > > CollectionUsage for that pool. > > > > For collectors other than G1 Young Generation, all pools are recorded as > > affected by all collections and every collection is recorded as > > affecting all the collector’s memory pools. For the G1 Young Generation > > collector, the G1 Old Gen pool is recorded as not being affected by all > > collections, and non-mixed collections are recorded as not affecting all > > memory pools. The result is that for non-mixed collections, > > CollectionUsage is recorded after a collection only the G1 Eden Space > > and G1 Survivor Space pools, while for mixed collections CollectionUsage > > is recorded for G1 Old Gen as well. > > > > Other than the effect of the fix on G1 Old Gen MemoryPool. > > CollectionUsage, the only external behavior change is that > > GarbageCollectorMXBean.getMemoryPoolNames will now return 3 pool names > > rather than 2. > > > > With this fix, a collector’s memory pools can be divided into two > > disjoint subsets, one that participates in all collections and one that > > doesn’t. This is a bit more general than the minimum necessary to fix > > G1, but not by much. Because I expect it to apply to other incremental > > region-based collectors, I went with the more general solution. I > > minimized the amount of code I had to touch by using default parameters > > for GCMemoryManager::add_pool and the TraceMemoryManagerStats constructors. > > >
