IIRC correctly, I am the author of the hacky 2-element charset cache. Certainly improvements can be made, but it's hard to balance memory usage vs. the cost and complexity of writing a good cache.
I agree with Sherman that a race in the cache itself is not a bug (or at best, a performance bug). I don't think it's worth a point fix here unless an actual wrong result can be demonstrated. I do think a more sophisticated charset cache would be good, but hard to get right. Martin On Wed, Oct 7, 2009 at 14:01, Xueming Shen <xueming.s...@sun.com> wrote: > Ulf Zibis wrote: >> >> Sherman, thanks for your review ... >> >> Am 07.10.2009 19:56, Xueming Shen schrieb: >>> >>> Though I did not write the cache code my reading suggests the existing >>> cache >>> impl tries to avoid the relatively "expensive" synchronization for most >>> use scenarios, >>> your approach however hits the synchronization for each/every lookup >>> invocation. >>> So you should at least consider to put the sync block in a separate >>> lookup2. >> >> Agreed: >> (But why separate lookup2? I suspect that Charset.forName() would occur in >> excessive loops, so hotspot potentially cold inline it.) > > Maybe I meant to say "to put the sync in a separate block" > >> >> Is synchronization more expensive, than instantiating new Object[] each >> time + 2 castings (to String + to Charset)? >> > > The difference is fast cpu + a good gc probably can make "instantiating new > Object[] each time + 2 castings" trivial, > but a synchronization only allows one thread run into the code block and > keeps anyone else outside waiting till the > first done. > >>> >>> But personally I doubt we really care this "race condition", it's a >>> cache, a cache miss >>> is not a disaster, >> >> OK, but why didn't you you reject Bug Id 6881442 with the same >> argumentation. >> ... and missing the class's name in Class.name could only happen once, in >> contrast to "my" race condition, which theoretically could happen every >> time. > > The difference is that race condition may cause a wrong result, In this case > the result is still correct though it > might come out at a relatively slow speed should the race condition occur. > > > sherman >
