The lazy sequence works with the code I provided as well.
On Tuesday, August 23, 2016 at 9:29:08 AM UTC-4, Sergei Koledov wrote:
>
> Yes, you are absolutely right. After i modify the code as you advised, it
> worked correctly. Thank you very much!
> Does it mean that is necessary to avoid the use of lazy data structures
> within the STM?
>
> вторник, 23 августа 2016 г., 19:57:58 UTC+7 пользователь hitesh написал:
>>
>> Taking a quick look at this, I *think* the problem crops up in your tasks
>> being a lazy sequence.
>>
>> Modify this
>>
>> (def tasks (ref (range 1 10000000)))
>>
>> to this
>>
>> (def tasks (ref (doall (range 1 10000000))))
>>
>> Running that with your large endpoint was taking a lot of time, so I'd
>> suggest running it with 1e5 as that will finish much quicker.
>>
>>
>>
>> On Tuesday, August 23, 2016 at 8:22:00 AM UTC-4, Sergei Koledov wrote:
>>>
>>> Hello,
>>>
>>> I had a problem when I run the following code:
>>>
>>> (defn get-task [tasks]
>>> (dosync
>>> (let [task (first @tasks)]
>>> (alter tasks rest)
>>> task)))
>>>
>>> (defn worker [& {:keys [tasks]}]
>>> (agent {:tasks tasks}))
>>>
>>> (defn worker-loop [{:keys [tasks] :as state}]
>>> (loop [last-task nil]
>>> (if-let [task (get-task tasks)]
>>> (recur task)
>>> (locking :out (println "Last task: " last-task))))
>>> state)
>>>
>>> (defn create-workers [count & options]
>>> (->> (range 0 count)
>>> (map (fn [_] (apply worker options)))
>>> (into [])))
>>>
>>> (defn start-workers [workers]
>>> (doseq [worker workers] (send-off worker worker-loop)))
>>>
>>> (def tasks (ref (range 1 10000000)))
>>>
>>> (def workers (create-workers 100 :tasks tasks))
>>>
>>> (start-workers workers)
>>> (apply await workers)
>>>
>>> Description: I have several agents (100 in my case). Each agent running
>>> in a separate thread. All agents share the one ref with the collection of
>>> tasks (range of longs in my case). Each agent get tasks from the collection
>>> (in transaction) one by one until the collection becomes empty and then
>>> prints the last task which it handle. However, when I run this code it
>>> looks like the collection of tasks suddenly becomes empty and workers
>>> handle only portion of all tasks (average 25-40% of all number).
>>>
>>> This code behave as I expected, when I create only one agent or use
>>> explicit locking in get-task function:
>>>
>>> (defn get-task [tasks]
>>> (locking :lock
>>> (dosync
>>> (let [task (first @tasks)]
>>> (alter tasks rest)
>>> task))))
>>>
>>> I run this code on the Clojure 1.8.0
>>> java version "1.8.0_91"
>>> Java(TM) SE Runtime Environment (build 1.8.0_91-b14)
>>> Java HotSpot(TM) 64-Bit Server VM (build 25.91-b14, mixed mode)
>>>
>>> Can anyone tell me, what am I doing wrong, or it really looks like a bug
>>> in the clojure STM?
>>> I already asked this question on stackoverflow.com (
>>> http://stackoverflow.com/questions/39054911/strange-behavior-of-clojure-ref),
>>>
>>> but so far nobody has been able to help me.
>>>
>>> P.S. Sorry for my english skill.
>>>
>>
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