Re: objectsWithFetchSpecification freezes during a slow call

Hi Mark,

It freezes for a while (10+ seconds) or it freezes forever?  Have you tried a "sudo jstack -F <process id> to see where it is frozen?  It does sound like a timeout thing, perhaps at the JDBC level.  Does CREATED_DATE have an index?  CREATED_DATE, QUEUE_ITEM_PK would be the fastest.

Chuck


On 2013-08-08, at 10:22 AM, Mark Gowdy wrote:

> Hi, 
> 
> Have been trying to track down the cause of a very strange problem we have been having.
> 
> Using the MySQLPlugIn in Wonder, if we do a fetch (or anything SQL related), and it takes a while for MySQL to respond, the instance freezes (it does not get past the objectsWithFetchSpecification line).
> We originally thought it was something to do with the memory & tables becoming large, but now we are thinking it is a response time-out thing.
> 
> We can reproduce the problem quite easily now by specifying a sort ordering, we will give MySQL a bit of work to do (and slow down the response).
> 
> So, if we run the generated SQL directly in Sequel Pro:
> 
> (1) Including the slow field (CREATED_DATE)- Takes about 10 seconds for MySQL to return some values.
> SELECT RTRIM(t0.CONFIG), t0.CREATED_DATE, t0.IDENTIFIER_1, t0.IDENTIFIER_2, t0.IDENTIFIER_3, t0.IDENTIFIER_4, t0.ITEM_DATE, t0.MODIFIED_DATE, t0.QUEUE_DETAILS_FK, t0.QUEUE_ITEM_PK, t0.QUEUE_TAG, t0.STATUS FROM queue_item t0 WHERE (t0.QUEUE_TAG = 'mb:nui:RENDER_MEDIA' AND (t0.ITEM_DATE < '2013-08-08 16:46:17 Etc/GMT' OR t0.ITEM_DATE is NULL)) ORDER BY t0.CREATED_DATE ASC, t0.QUEUE_ITEM_PK ASC LIMIT 50
> 
> (2) Remove the slow sort field - Takes about 72ms for MySQL to return some values.
> SELECT RTRIM(t0.CONFIG), t0.CREATED_DATE, t0.IDENTIFIER_1, t0.IDENTIFIER_2, t0.IDENTIFIER_3, t0.IDENTIFIER_4, t0.ITEM_DATE, t0.MODIFIED_DATE, t0.QUEUE_DETAILS_FK, t0.QUEUE_ITEM_PK, t0.QUEUE_TAG, t0.STATUS FROM queue_item t0 WHERE (t0.QUEUE_TAG = 'mb:nui:RENDER_MEDIA' AND (t0.ITEM_DATE < '2013-08-08 16:46:17 Etc/GMT' OR t0.ITEM_DATE is NULL)) ORDER BY t0.QUEUE_ITEM_PK ASC LIMIT 50
> 
> Now, in our app, during the objectsWithFetchSpecification(..)
> (1) freezes the app totally.. no error messages, just frozen.
> (2) works fine.
> 
> Any thoughts?
> 
> Thanks, 
> 
> Mark
> 
> 
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-- 
Chuck Hill             
Executive Managing Partner, VP Development and Technical Services

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Download for free and get started troubleshooting in minutes. 
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