[rules-users] Multi Access to Stateful Session
Wolfgang Laun
wolfgang.laun at gmail.com
Mon Apr 2 14:12:16 EDT 2012
Another poster on this list has stated that there are flaws in the
synchronization of Drools, but IIRC this was related to an older
version.
I can propose two additional experiments:
(1) Have you ever run this with insertions from a single thread, and with the
engine being run in one other thread?
(2) Run an experiment where you call fireAllRules() after each
insertion, with insertions from multiple threads.
-W
On 02/04/2012, gboro54 <gboro54 at gmail.com> wrote:
> I updated the MessageControl fact as follows and the same issue still
> occurs:
>
> private Long currentPosition = new Long(0);
> private Set<Long> excludedPositions = new HashSet<Long>();
>
> public synchronized void addPositionToExclusionList(Long position) {
> excludedPositions.add(position);
> }
>
> public synchronized Long getCurrentPosition() {
> return currentPosition;
> }
>
> public synchronized void moveCurrentPositionForward(Integer value) {
> currentPosition += value;
> if (currentPosition % 20000 == 0) {
> System.out.println(currentPosition);
> }
>
> }
>
> public synchronized boolean atExcludedPosition() {
> return excludedPositions.contains(currentPosition);
> }
>
> Not sure what else could occur between the insertions and the rule execution
> that would be an issue...
>
>
> laune wrote
>>
>> So it looks like a race condition.
>>
>> There is one chink in the snchronizing armour of class MessageControl.
>> The Map excludedPositions (although in itself synchronized on its own
>> lock) is exposed via the getExcludedPositions. Thus, synchronization
>> between currentPosition and excludedPositions is broken. I can't say
>> whether this matters, but just try and add delegating methods to
>> MessageControl and remove getExcludedPositions. (And use a plain
>> HashSet - synchronization is provided by MessageControl.)
>>
>> Obviously, rules will have to use something like
>> atExcludedPosition == true
>> when the Map is fully privatized.
>>
>> -W
>>
>>
>> On 02/04/2012, gboro54 <gboro54@> wrote:
>>> A gap would have to occur somewhere but I am not sure how or why.
>>> Since I am using the same data for each test case, the outcome should
>>> be the same but 75% of the time to position stops at a random point
>>> and thus allows messages to backup in memory
>>>
>>> On Mon, Apr 2, 2012 at 12:19 PM, laune [via Drools]
>>> <ml-node+s46999n3878174h55 at .nabble> wrote:
>>>> What is the current position value in the controller when it blocks? A
>>>> regular message rank or one of those not to be processed or both?
>>>>
>>>> Are you sure that message ranks are increasing without gaps except
>>>> those in the excluded position map?
>>>>
>>>> -W
>>>>
>>>> On 02/04/2012, gboro54 <[hidden email]> wrote:
>>>>
>>>>> Forgo to mention each time a position is added to the excluded position
>>>>> map,
>>>>> the insertOrUpdate method is called on the session wrapper.
>>>>>
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>>>>>
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