I think you mean RamUsageEstimator (in Lucene's test-framework)? It's entirely possible it fails to dig into Maps correctly with newer Java releases; maybe Dawid or Uwe would know?
Mike McCandless http://blog.mikemccandless.com On Tue, Dec 4, 2018 at 12:18 PM Michael Sokolov <msoko...@gmail.com> wrote: > Hi, I'm using RamUsageCrawler to size some things, and I find it seems > to underestimate the size of Map (eg HashMap and ConcurrentHashMap). > This is using a Java 10 runtime, with code compiled to Java 8. I > looked at the implementation and it seems as if for JRE classes, when > JRE >= 9, we can no longer use reflection to size them accurately? > Instead the implementation estimates the map size by treating it as an > array of (keys and value) plus some constant header size. But this > seems to neglect the size of the HashMap$Node (in the case of HashMap > - I haven't looked at ConcurrentHashMap or TreeMap or anything). In my > case, I have a great many maps of a relatively small number of shared > keys and values, so the crawler seems to be wildly under-counting. I'm > comparing to sizes gleaned from heap dumps, eclipse mat, and OOM > events. > > I wonder if we can we improve on the estimates for Maps and other > Collections? > > --------------------------------------------------------------------- > To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org > For additional commands, e-mail: java-user-h...@lucene.apache.org > >
