Ask Ben: Limiting The Amount Of Time A Block Of Code Can Run (Attempt II)
Posted April 2, 2007 at 10:00 AM
I have this application that uses a black-boxed piece of functionality. 98% of the time, this black-boxed functionality runs very fast as expected. Sometimes though, for reasons I cannot yet debug, this function takes so long that the page times out. Is there a way to make sure that just this block of code only executes for X number of seconds?
Ok, my last attempt at answering this question was a total failure that demonstrated my lack of understanding regarding the CFLock tag. Thankfully, Christoph Schmitz has shown my the light. I have re-attempted an answer using the CFSetting / RequestTimeOut tag and attribute. I am not 100% sure it can be done this way, but testing seems to say that Yes, it can.
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- <!--- Try to execute the following block of code. --->
- <cftry>
-
- <!---
- By setting a request time out for this page, we are
- forcing it to have a maximum amount of time that it
- can run. Since the black-boxed code comes after it,
- it will be dominated by this CFSetting.
- --->
- <cfsetting
- requesttimeout="5"
- />
-
-
- <!---
- This is our black-boxed piece of code. Not
- sure how it works, but we know that 2% of the
- time it runs way longer than it should and
- crashes the page.
- --->
- <p>
- This will only be allowed to execute for
- a maximum of 5 seconds.
- </p>
-
-
- <!---
- Catch an errors that get thrown from our
- code exceeding the CFSetting timeout attribute.
- --->
- <cfcatch>
-
- <!---
- Our black-boxed piece of code has run too
- long. Use this opprotunity to set default
- values so that you might be able to recover
- from this timeout.
- --->
-
- <!---
- Since the rest of the page will take some time
- to execute, set a new time out for this request.
- --->
- <cfsetting
- requesttimeout="60"
- />
-
- <!--- Perform recovery code here. --->
-
- </cfcatch>
-
- </cftry>
Hopefully this is better.
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Ask Ben: Limiting The Amount Of Time A Block Of Code Can Run
Reader Comments
while this solution would work for a calling template, it won't work within a function. I think what the person is asking is if they can make a CFC method time out after a certain amount of time. Now personally I have no idea how to do this.
Posted by tony petruzzi on Apr 3, 2007 at 8:54 AM
Yeah, this seems to be a very difficult task (or something simple that I am just not thinking of). I saw a presentation on Blue Dragon not so long ago and they had a CFThread tag... I wonder if the CFThread tag has a timeout attribute; that seems like something that would do the trick here - wrapping the "locked down" code in a CFThread tag and forcing a small timeout.
Posted by Ben Nadel on Apr 3, 2007 at 9:02 AM
When I use "while" loops, I often do something like this:
-----------------------
<!--- Set the time before entering the loop --->
<cfset var timeout = now() />
<cfloop condition="TRUE">
...do something here...
<!--- End the loop if it has run for more than five seconds --->
<cfif dateDiff("s", timeout, now()) GTE 5>
<cfbreak />
</cfif>
</cfloop>
-----------------------
Of course, that won't prevent the processing during an individual iteration of the loop from running more than five seconds.
Posted by Steve on Apr 5, 2007 at 12:26 AM
