[ZCM] [ZC] 1633/ 3 Comment "Lurking CPU eater in Transience"

[Collector: Zope Bugs, Features, and Patches ...]

Issue #1633 Update (Comment) "Lurking CPU eater in Transience"
 Status Accepted, Zope/bug+solution medium
To followup, visit:
  http://collector.zope.org/Zope/1633

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= Comment - Entry #3 by evan on Dec 20, 2004 1:54 pm

Inserting or deleting elements or replacing a slice that spans the current element in a for-loop is generally a bad idea.  Changing the value of a list element is fine.
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= Comment - Entry #2 by mcdonc on Dec 20, 2004 1:10 pm


>   This was due to it inserting tens of thousands of elements into the head
>   of an empty list, one at a time.  While I learned my lesson, and bumped
>   the resolution up to match the timeout, I also decided to fix
>   getTimeslices.  A patch is attached.

Cool, thanks!  I'm wondering, though, I've always heard it was bad to mutate a list while iterating over it.  Does that only matter if you change the size of the list while doing so?
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= Request - Entry #1 by evan on Dec 20, 2004 12:02 pm

 Status: Pending => Accepted

 Supporters added: chrism


Uploaded:  "p"
 - http://collector.zope.org/Zope/1633/p/view
I foolishly set the timeout of a Transient Object Container to a very high value while leaving the timeout resolution at 20.  Subsequent profiling revealed that Transience.py's getTimeslices was using 100% CPU for more than a second every time it was called, which was frequently.  This was due to it inserting tens of thousands of elements into the head of an empty list, one at a time.  While I learned my lesson, and bumped the resolution up to match the timeout, I also decided to fix getTimeslices.  A patch is attached.
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