No please. The store module is perfect as it is for a lot of out-of-band activities. If this can not be implemented in an optional way leave it off. Thanks.
I'll try to go with Andy's suggestion or resolve to using a DB in the critical cases.
Regards,
Marco.
On 22/02/25 11:38, Christian Grün wrote:
Hi there,
The semaphore code looks fine. As Andy noted, things get much more complicated when the code needs to run across multiple concurrent jobs: We might easily run into deadlocks.
Thus, if it turns out that concurrency gets a bigger issue, we would probably embed key/value store updates into our Pending Update List concept, even if it would make it less flexible to use.
Cheers, Christian
On Sat, Feb 8, 2025 at 12:07 PM Marco Lettere m.lettere@gmail.com wrote:
For us it can be solved with custom annotations or even constant strings because it all comes down to the one workflow engine ... Il sab 8 feb 2025, 11:55 Andy Bunce <bunce.andy@gmail.com> ha scritto: One problem with this might be that: When using the fork-join function it is easy to ensure all the threads have a reference to the *same* semaphore. If these were arbitrary BaseX "jobs" it is not clear how this could be done without explicit support from the BaseX runtime. Perhaps it could be done with a new annotation %basex:semaphore ("my-semaphore") that could be applied to functions. /Andy On Fri, 7 Feb 2025 at 18:31, Marco Lettere <m.lettere@gmail.com> wrote: Oh, wow. Looks great Andy. Thanks for suggestion. Wonder to know what's Christian's opinion on this. M. On 07/02/25 16:45, Andy Bunce wrote:>so if you call store:get, store:put or store:write in the first process, a second process will not wait until the store operations are completed. In non XQuery contexts a semaphore [1] might be used to ensure that my other threads don't get between a get and put. In the spirit of blurring the XQuery Java boundaries I tried [2]. It seems to work. Is it dangerous? [1] https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/Semaphore.html [2] declare namespace Semphore ="java:java.util.concurrent.Semaphore"; declare function local:config-update($k as xs:string,$v as item(),$sem) { Semphore:acquire($sem), try{ let $u:=store:get("config")=> map:put($k, $v) return store:put("config",$u) }catch * { trace("Errrr",$err:description) } ,Semphore:release($sem) }; let $sem:=Semphore:new(1,true()) let $s1 := store:put("config", map{}) let $s2 := xquery:fork-join( for $i in (1 to 100) return function(){ let $r:=(prof:sleep(10),$i) return local:config-update( string($i),$r,$sem) } ) return count(map:keys(store:get("config"))) On Tue, 28 Jan 2025 at 14:09, Marco Lettere <m.lettere@gmail.com> wrote: Ok, thanks for the clarification. M. On 28/01/25 15:08, Christian Grün wrote:Sorry Christian, do you mean *not* synchronized? With »synchronized«, I meant to refer to a lower level: You will not end up with a corrupt key/value store or with I/O conflicts when accessing and updating the store via multiple threads. However, as you have already observed, multiple operations are not executed in a well-defined order, so if you call store:get, store:put or store:write in the first process, a second process will not wait until the store operations are completed.