Drools 4.0.7

Are running drools queries against working memory thread safe? I know that inserts and retracts need to be synchronized but what about queries? I would am considering having multiple threads querying working memory for different facts at the same time.

For example:

final QueryResults results = workingMemory.getQueryResults("GetMCCObjects");
for (Iterator it = results.iterator(); it.hasNext(); ) {
       result = (QueryResult) it.next();
        mccDelObj = (MerchantCategoryGroup) result.get("mccObjects");
        fhMCCGroup = workingMemory.getFactHandle(mccDelObj);
        WMSyncdInsertRetract(fhMCCGroup, RETRACT);
}

Scott