John,
The NDC code is well tested. It should work all the time unless one *never* calls
NDC.remove(). I'd be surprised to hear otherwise. Ceki
At 15:48 12.06.2001 -0400, you wrote:
>Hmm,
>
>We are preparing to do some preliminary load testing on our application here, and had
>actually figured on relying on the lazy NDC.remove() behaviour. (We figured that at
>least initially it should be good enough.)
>
>Does it seem to not work 1)at all, or 2)poorly, or what?
>
>I've looked at the source code for the NDC class and it seemed perfectly adequate and
>correct. (That is of course by no means a GOOD test of it, but hey it LOOKS like it
>should work!)
>
>So, do you have more details on what you observe to be it's issues?
>
>John Volkar
>
>
>-----Original Message-----
>From: Wes [mailto:[EMAIL PROTECTED]]
>Sent: Tuesday, June 12, 2001 1:37 PM
>To: [EMAIL PROTECTED]
>Subject: NDC.remove / memory issues
>
>We just began stress testing our application, and found memory leaks. Eventually, I
>isolated the leak to the NDC push/pop that we were doing in each thread that was
>created. Then, after looking more carefully at the NDC class documentation, I saw
>the following regarding the remove method:
>
>"Remove the diagnostic context for this thread.
>
>Each thread that created a diagnostic context by calling
><file:///C:/wes/jakarta-log4j-1.1.2/docs/api/org/apache/log4j/NDC.html#pop()>pop()
>should call this method before exiting. Otherwise, the memory used by the diagnostic
>context for the thread cannot be reclaimed by the VM.
>As this is such an important problem in heavy duty systems and because it is
>difficult to always guarantee that the remove method is called before exiting a
>thread, this method has been augmented to lazily remove references to dead threads.
>In practice, this means that you can be a little sloppy and occasionally forget to
>call
><file:///C:/wes/jakarta-log4j-1.1.2/docs/api/org/apache/log4j/NDC.html#remove()>remove()
> before exiting a thread"
>
>I had not known about the remove method, probably because I initially looked only at
>a few examples, such as Trivial.java, and the remove was not used there. I also
>noticed that the documentation for the push and pop methods does not mention the
>remove() method at all.
>
>Furthermore, according to the remove() documentation, we should be OK anyway because
>of the lazy cleanup mechanism, but according to our tests, it did not clean up
>enough, as we eventually ran out of memory.
>
>So, if anyone else is currently doing push/pop in threads that come and go
>frequently, be sure to call remove as the thread exits... and perhaps the remove
>method could be mentioned in the documentation for push and pop.
>
>Wes
>
--
Ceki Gülcü
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