Memory Woes

[Kevin@Cazabon.com]

How about update the existing chart every second, and draw a new chart every
minute?  If the "lost" memory is recovered when you delete the original
chart altogether, it might be a good balance between performance and memory
usage.  Still a workaround to the real problem though.

Kevin.

"Scherer, Bill" <Bill.Scherer at verizonwireless.com> wrote in message
news:mailman.1046284211.5592.python-list at python.org...
> On 26 Feb 2003, Greg wrote:
>
> > I am using Python 2.2 to write a chart that plots realtime data
> > similar to the one on the performance tab of the Windows task manager.
> >
> > Here's the problem:
> >   I use a Tkinter canvas widget to display the data, and on each
> > update (1/sec), the data and x gridlines scroll to the left.  If I
> > don't delete any items from the canvas, the memory usage (as reported
> > by the task manager) increases slowly.
>
> [P&M]
>
> I had a similar chart with the same problem. I found no solution
> to the memory consumption with that method.  My charts are only
> updating once a minute, so what I do now is put my data into a
> list, and trim that as needed. The chart is then completely
> redrawn from the data in the list, every minute.
>
> I suspect this method would flicker madly at 1Hz, but maybe it
> won't on your particular hardware???
>
> Good luck!
> - Bill
>
> > This is understandable, since
> > the canvas is still keeping track of the items that are no longer
> > visible.  When I attempted to remedy this by deleting the items as
> > they scroll off the chart, however, it began eating memory about 5
> > times faster.
> >
> > Here's the code I use to search and destroy items that are scrolling
> > off the chart:
> >
> >   # every item that scrolls along the x axis is given a "deleteMe"
> >   # tag upon creation
> >   for i in self.canvas.find_withtag("deleteMe"):
> >     # margins[3] represents the left margin (the x coordinate of
> >     # the y axis)
> >     if self.canvas.coords(i)[0] <= self.margins[3]:
> >       self.canvas.delete(i)
> >
> > I've read quite a few posts that suggest memory leaks with callback
> > bindings in older versions of tk, but I don't have any bindings
> > attached to any of the deleted items, and "deleteMe" is the only tag
> > associated with any of them.
> >
> > This script is meant to run over long periods of time, and the memory
> > usage will become a major issue as time goes on.  Any thoughts as to
> > why this is happening/how to fix it?  I'm fairly new to python and to
> > gui programming, so feel free to let me know if I'm doing something
> > completely idiotic.
> >
> > Thanks,
> >   Greg
> >
>
>
>