From: "Adrian Crum" <adrian.c...@sandglass-software.com> > Thanks Jacopo. I haven't looked into the entity cache implementation > thoroughly, but I was under the impression that it can be configured to > be distributed.
Yes it is https://cwiki.apache.org/confluence/display/OFBIZ/Distributed+Entity+Cache+Clear+Mechanism Jacques > I have the fix working on my local copy. As you can see, I have made > some related changes already and will be making some more, but I won't > commit the fix until next weekend - to give everyone a chance to respond. > > -Adrian > > On 4/22/2013 9:33 AM, Jacopo Cappellato wrote: >> It seems actually to be an issue rather than a feature (I can't think of a >> use case where this behavior would be useful); I have created a few test >> cases (similar to the one you have provided in the other thread) that >> further analyze your discovery but they don't add much to what you found >> (apart from confirming the risk of getting stale data). >> However, when we start design/implement a refactoring of this part of the >> system, I would suggest that we also consider how to deal with similar >> scenarios in a clustered deployment (in fact many of the production >> deployment are based on clusters); the simplest use case could be: in a >> cluster, we have two OFBiz instances connected to the same database; in one >> instance the list is cached, in the other instance one of the generic values >> (that are part of the selection) is updated. A distributed cache system may >> help here. >> >> Jacopo >> >> On Apr 21, 2013, at 10:54 AM, Adrian Crum >> <adrian.c...@sandglass-software.com> wrote: >> >>> Last week I discovered a flaw in the EntityListCache implementation: >>> http://mail-archives.apache.org/mod_mbox/incubator-ofbiz-dev/201304.mbox/%3c516ac7b4.2020...@sandglass-software.com%3E >>> >>> To summarize: Entity conditions that are cached become stale when any >>> member of the cached list is changed - making the cache contents invalid. >>> In addition, GenericValues in the cached list are mutable - which is >>> inconsistent with the primary key cache, where GenericValues from the cache >>> are immutable. >>> >>> I would like to fix this, but I think we should discuss it first. >>> >>> One change would be to make the list member GenericValues immutable. This >>> will make the GenericValues retrieved from the entity list cache consistent >>> with the GenericValues retrieved from the primary key cache, but it won't >>> prevent an invalid cache (because the list member GenericValue can be >>> cloned and modified). Also, this change will likely break a lot of code, >>> because it is common to retrieve a list of GenericValues from the cache and >>> then make changes to the list members. We could create a "transitional" >>> GenericValue that would warn developers when they modify a cached list >>> member, and then switch to an immutable GenericValue some time in the >>> future. >>> >>> To fix the stale cache problem, the cache instance can be made a >>> GenericValue listener in all of its list members - so any time a list >>> member is modified the cache will be cleared. This will keep the cache >>> valid, but there might be a performance hit. I'm open to other solutions to >>> this problem. >>> >>> Any thoughts? >>> >>> -Adrian >>> >>> >
