On 04/21/2016 06:07 PM, Peter Levart wrote:
I propose to add a thread-safe WeakPairMap data structure which associates a pair of weakly-reachable keys with a strongly-reachable value based on ConcurrentHashMap. Such data structure is footprint-friendly, since only a single instance exists for a particular purpose, totaling 3 instances for the transient structures serving all Modules in the system:
http://cr.openjdk.java.net/~plevart/jdk9-dev/Module.WeakSet.multithreadUnsaf...
Oops... It looks like I replaced one thread-unsafe construction with another one: 389 // additional exports added at run-time 390 // source module (1st key), target module (2nd key), exported packages (value) 391 private static final WeakPairMap<Module, Module, Set<String>> transientExports = 392 new WeakPairMap<>(); ...that would've been OK if I hadn't used normal HashSet for holding the set of packages: 623 // add package name to transientExports if absent 624 transientExports 625 .computeIfAbsent(this, other, (_this, _other) -> new HashSet<>()) 626 .add(pn); Luckily this can be easily fixed by using a ConcurrentHashMap instead of HashSet which is even more space-friendly (HashSet is just a wrapper around HashMap and HashMap is basically the same structure as ConcurrentHashMap): http://cr.openjdk.java.net/~plevart/jdk9-dev/Module.WeakSet.multithreadUnsaf... Regards, Peter