[MapProxy] Threading & Memory Errors

Keith Moss Keith.Moss at landgate.wa.gov.au
Thu Mar 7 19:56:13 PST 2013

Hi Olivier,

At the time I didn't but I've been collecting stats on memory usage over the past week.

We had Apache set to recycle the httpd.exe process after 60k requests and after reducing it to 30k we've not seen the memory errors occurring at any point in the past 7 days.

With a 30k limit httpd.exe gets to between 250MB and 360MB (from a base of 50MB). The server has 4GB of memory available to it and generally sits between 30 - 60% free with only occasional spikes to near 100% used.

The only other procesess of note are php-cgi.exe instances, which don't consume much more than a 125MB each before being recycled.

We're using MapProxy as WMS server in front of five load balanced servers running MapServer. We're typically seeing between 40k and 80k requests to MapProxy per day and between 13k and 25k requests back to MapServer (for 928x928 images).


Keith Moss
Satellite Remote Sensing Services
65 Brockway Road, FLOREAT WA 6014
PO Box 741 Wembley WA 6913
Ph. (08) 9387 0332 | Fx. (08) 9383 7142
keith.moss at landgate.wa.gov.au

From: Oliver Tonnhofer [olt at omniscale.de]
Sent: Wednesday, 27 February 2013 8:36 PM
To: Keith Moss
Cc: mapproxy at lists.osgeo.org
Subject: Re: [MapProxy] Threading & Memory Errors

Hi Keith,

On 25.02.2013, at 04:38, Keith Moss wrote:
> We've started noticing memory and threading errors. (stacktrace attached below)
> We've noticed the "can't start new thread" errors in small amounts previously, but in the past couple of days (which did correspond roughly with spikes in usage) we've seen them in much larger numbers (~2000 on Sunday, another 600 this morning before Apache restarted itself). The "out of memory" errors have different stacktraces each time (as you might expect). I haven't got any data yet on what memoy usage on the server is at these times but I've never seen it come close to maxing out the available memory when I've been monitoring it. The httpd process does seem to be gradually growing its memory usage all of the time, though.

I'm not aware of any memory leaks in MapProxy or it's dependencies.

Do you have some numbers of the memory usage of the httpd process over time? How much memory has the server? How much is typically free? Are there any other memory hogs on the machine?

And how do you use MapProxy? Tile server? WMS server? Do you make large requests (say 2000x2000 or larger)?


Oliver Tonnhofer    | Omniscale GmbH & Co KG    | http://omniscale.com
http://mapproxy.org | https://github.com/olt    | @oltonn
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