[rules-users] Multi Access to Stateful Session

[Wolfgang Laun]

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 &lt;gboro54@&gt; 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]
>>> &lt;ml-node+s46999n3878174h55 at .nabble&gt; 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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