On Oct 14 2013, at 02:32 , Paul Sandoz wrote: >> Virtually all the cases where CME is thrown in the "new" Map defaults are >> the points where previously the implementation would have looped/retried. >> > >>> For the cases where no function values are passed it has very limited >>> value, we know it is effectively useless for non-current collections being >>> modified concurrently. >> >> Understood. The alternative would be to GIGO these situations, return and >> ignore them. >> > > Yeah, unnecessarily complicates the code.
It does detect legitimate errors and it makes me uncomfortable to just ignore them. >>> For the cases where a function value is passed and it modifies the map then >>> it could have some value. But i wonder, for any non-looping function value >>> accepting method on Map (anything other than forEach/replaceAll), whether >>> it is just simpler to state: "if a function value modifies the entry under >>> computation then this method may return incorrect results`". >> >> Modification of any other entry may have the same result. > > Yes, although IIUC modification, by the function value, of other entries will > not interfere with that of operating on the entry under computation. A more > general recommendation is the function values should be stateless. > > >> I suspect that modification by some other thread is as likely to be a >> problem as modification by the function. >> > > And under concurrent modification we cannot deterministically detect. CME in > the non-concurrent collections is only useful for detecting serial > modification due to inversion of control, and in these particular cases it is > really very limited as to what it detects. True, but it generally doesn't impose any extra cost. The error detection happens as a side effect of necessary operations. I'd like to bring this set of changes to conclusion as soon as possible. Mike
