I'm sorry but I'm not following what you're proposing. Currently row changes caused within a transaction are available only to queries issued within that same transaction (i.e. read committed), except that the cache breaks this isolation by making them immediately available to any transaction querying that entity. I don't see how this scenario exists outside of the cache unless the logic within the transaction explicitly passes a row off to another transaction, and I'm not aware of any cases like that.
On Thu, Mar 19, 2015 at 3:17 AM, Adrian Crum < adrian.c...@sandglass-software.com> wrote: > I call it an edge case because it is easily fixed by changing the > transaction isolation level. > > The behavior you describe is not caused by the entity cache, but by the > transaction isolation level. The same scenario would exist without the > entity cache - where two processes hold a reference to the updated row, and > one process performs a rollback. > > Adrian Crum > Sandglass Software > www.sandglass-software.com > > On 3/19/2015 7:28 AM, Scott Gray wrote: > >> Ah, it's quite a large edge case IMO >> >> On Thu, Mar 19, 2015 at 12:20 AM, Adrian Crum < >> adrian.c...@sandglass-software.com> wrote: >> >> That is the edge case I mentioned. >>> >>> Adrian Crum >>> Sandglass Software >>> www.sandglass-software.com >>> >>> On 3/19/2015 6:54 AM, Scott Gray wrote: >>> >>> I tend to disagree with the "cache everything" approach because the >>>> cache >>>> isn't transaction aware. >>>> If you: >>>> 1. update a record >>>> 2. select that same record >>>> 3. encounter a transaction rollback >>>> >>>> Then the cache will still contain the changes that were rolled back. >>>> >>>> Regards >>>> Scott >>>> >>>> >>>> On Wed, Mar 18, 2015 at 5:16 AM, Adrian Crum < >>>> adrian.c...@sandglass-software.com> wrote: >>>> >>>> I would like to share some insights into the entity cache feature, >>>> some >>>> >>>>> best practices I like to follow, and some related information. >>>>> >>>>> Some OFBiz experts may disagree with some of my views, and that is >>>>> okay. >>>>> Different experiences with OFBiz will lead to different viewpoints. >>>>> >>>>> The OFBiz entity caching feature is intended to improve performance by >>>>> keeping GenericValue instances in memory - decreasing the number of >>>>> calls >>>>> to the database. >>>>> >>>>> Background >>>>> ---------- >>>>> >>>>> Initially, the entity cache was very unreliable due to a number of >>>>> flaws >>>>> in its design and in the code that calls it (it was guaranteed to >>>>> produce >>>>> stale data). As a result, I personally avoided using the entity cache >>>>> feature. >>>>> >>>>> Some time ago, Adam Heath did a lot of work on the entity cache. After >>>>> that, Jacopo and I did a lot of work fixing stale data issues in the >>>>> entity >>>>> cache. Today, the entity cache is much improved and unit tests ensure >>>>> it >>>>> produces the correct data (except for one edge case that Jacopo has >>>>> identified). >>>>> >>>>> I mention all of this because the previous quirky behavior led to some >>>>> "best practices" that didn't make much sense. A search through the >>>>> OFBiz >>>>> mail archives will produce a mountain of conflicting and confusing >>>>> information. >>>>> >>>>> Today >>>>> ----- >>>>> >>>>> Since the current entity cache is reliable, there is no reason NOT to >>>>> use >>>>> it. My preference is to make ALL Delegator calls use the cache. If all >>>>> code >>>>> uses the cache, then individual entities can have their caching >>>>> characteristics configured outside of code. This enables sysadmins to >>>>> fine-tune entity caches for best performance. >>>>> >>>>> [Some experts might disagree with this approach because the entity >>>>> cache >>>>> will consume all available memory. But the idea is to configure the >>>>> cache >>>>> so that doesn't happen.] >>>>> >>>>> If you code Delegator calls to avoid the cache, then there is no way >>>>> for >>>>> a >>>>> sysadmin to configure the caching behavior - that bit of code will >>>>> ALWAYS >>>>> make a database call. >>>>> >>>>> If you make all Delegator calls use the cache, then there is an >>>>> additional >>>>> complication that will add a bit more code: the GenericValue instances >>>>> retrieved from the cache are immutable - if you want to modify them, >>>>> then >>>>> you will have to clone them. So, this approach can produce an >>>>> additional >>>>> line of code. >>>>> >>>>> >>>>> -- >>>>> Adrian Crum >>>>> Sandglass Software >>>>> www.sandglass-software.com >>>>> >>>>> >>>>> >>>> >>
