(defn insert-async!
[& args]
(db-thread
(try
(apply jdbc/insert! args)
(catch Throwable t
t))))
db-thread is a macro that runs the body in a fixed thread pool, so IO isn't
done inside a go block.
On Thursday, August 1, 2013 3:33:29 AM UTC+9, tbc++ wrote:
>
> DB work is a IO operation, and IO shouldn't be done inside a go block (go
> blocks use limited thread pools).
>
> So what about something like this?
>
> (defn handle-db [chan]
> (thread
> (while true
> (let [[data result] (<! c)]
> (run-db-transaction-as-normal data)
> (>! result :done)))))
>
> Now spin up a few of these:
>
> (def db-chan (let [c (chan 4)]
> (dotimes [x 4]
> (handle-db c))
> c))
>
> Now it's trivial to use this from a go block:
>
> (defn db-async [data]
> (go
> (let [c (chan)]
> (>! db-chan [data c])
> (<! c))))
>
> So this is the pattern: create processors using threads, then send data to
> those processors via a shared channel, passing in a response channel.
>
> Anyways, that's the way I'm thinking these days.
>
> Timothy
>
>
>
>
> On Wed, Jul 31, 2013 at 12:24 PM, Alice <[email protected]
> <javascript:>>wrote:
>
>> I have an async http handler and I don't want it to consume a thread.
>>
>> On Thursday, August 1, 2013 3:16:52 AM UTC+9, tbc++ wrote:
>>
>>> Why not use <!! ?
>>>
>>> Timothy
>>>
>>>
>>> On Wed, Jul 31, 2013 at 11:58 AM, Alice <[email protected]> wrote:
>>>
>>>> It doesn't produce a compile time error but I think it's not the
>>>> correct code because the transaction can be committed while insert-async!
>>>> is still executing.
>>>>
>>>> On Thursday, August 1, 2013 2:46:29 AM UTC+9, Sean Corfield wrote:
>>>>
>>>>> On Wed, Jul 31, 2013 at 10:29 AM, Alice <[email protected]> wrote:
>>>>> > (go
>>>>> > (jdbc/db-transaction [t-con db-spec]
>>>>> > (<! (insert-async! t-con :fruit {:name "apple"}))))
>>>>>
>>>>> Does this work:
>>>>>
>>>>> (jdbc/db-transaction [t-con db-spec]
>>>>> (go
>>>>> (<! (insert-async! t-con :fruit {:name "apple"}))))
>>>>>
>>>>> --
>>>>> Sean A Corfield -- (904) 302-SEAN
>>>>> An Architect's View -- http://corfield.org/
>>>>> World Singles, LLC. -- http://worldsingles.com/
>>>>>
>>>>> "Perfection is the enemy of the good."
>>>>> -- Gustave Flaubert, French realist novelist (1821-1880)
>>>>>
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>>>>
>>>>
>>>
>>>
>>>
>>> --
>>> “One of the main causes of the fall of the Roman Empire was that–lacking
>>> zero–they had no way to indicate successful termination of their C
>>> programs.”
>>> (Robert Firth)
>>>
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>
>
>
> --
> “One of the main causes of the fall of the Roman Empire was that–lacking
> zero–they had no way to indicate successful termination of their C
> programs.”
> (Robert Firth)
>
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