[Tilecache] Tilecache 2.0.1 Segfault

[Steve Lime]

It's almost like the tiles are somehow not being cleared from memory.

>>> On 3/18/2008 at 4:48 PM, in message <47DFF262.5157.008F.0 at dnr.state.mn.us>,
"Steve Lime" <Steve.Lime at dnr.state.mn.us> wrote:

> 
>>>> On 3/18/2008 at 2:24 PM, in message <20080318192428.GA16166 at metacarta.com>,
> Christopher Schmidt <crschmidt at metacarta.com> wrote:
>> On Mon, Mar 17, 2008 at 03:58:44PM -0500, Steve Lime wrote:
>>> Hi all: I'm using tilecache with a MapServer layer and running into problems 
> 
>> when seeding the cache. In this instance
>>> all the layers in the mapfile are STATUS DEFAULT, on all the time. Running 
>> the seeding program seems to work ok
>>> with 2 exceptions:
>>> 
>>>   1) for every tile I get a WMS exception
>>> 
>>>   <CTYPE ServiceExceptionReport SYSTEM 
>> "http://schemas.opengis.net/wms/1.1.1/exception_1_1_1.dtd">
>>>     <ServiceExceptionReport version="1.1.1">
>>>       <ServiceException code="LayerNotDefined">
>>>         msWMSLoadGetMapParams(): WMS server error. Invalid layer(s) given in 
> 
>> the LAYERS parameter.
>>>       </ServiceException>
>>>   </ServiceExceptionReport>
>>> 
>>> This is expected I guess since there is no layer specified in the 
>> tilcache.cfg file (since all are on by default). The
>>> tiles ARE created despite the error message. Would be nice to suppress that 
>> if it's benign.
>> 
>> Since TileCache uses the owsParams way of loading a mapobj, it has the
>> same requirements that a WMS Request does, so this is 'automatic': I'm
>> not sure how you're getting a WMS Exception but still getting tiles
>> created? That definitely seems weird to me.
> 
> Actually I figured this out. The MapServer layer calls the 
> msWMSLoadGetMapParams()
> function through MapScript to populate the mapObj. That function is throwing 
> the
> WMS exception but nothing is detecting the exception so the draw() method is
> being executed. It may just be luck that this works so don't change 
> anything. Using
> all default layers seems a reasonable use case to me.
> 
>>>   2) after every 500 to 1,000 tiles or I get a segmentation fault. No other 
>> error information
>>> 
>>> If I re-run the seed command it picks up again from where it dies, although I 
> 
>> sometimes have to run it twice to clear
>>> our any file locks. It'll run another 500 to 1,000 or so and it dies again.
>>> 
>>> Could be a MapServer issue or TileCache, not sure. The debugger gives me:
>>> 
>>>   Program received signal SIGSEGV, Segmentation fault.
>>>   [Switching to Thread 1075357376 (LWP 31768)]
>>>   0x400d8f4c in mempcpy () from /lib/tls/libc.so.6
>>> 
>>> Has anyone else into anything like this?
>> 
>> I've seen this on a SuSE box as well. (Specifically, 'hypersphere', a
>> telasciecne/OSGeo machine.) As far as I know, this is a MapServer
>> segfault of some kind: does a backtrace help you here? I've never had
>> the desire to debug it, to be honest. I've never had it happen on
>> Debian.  
> 
> I'm sitting here watching "top" output will running the seeding and the 
> python
> process is gobbling up memory like crazy (1.3Gb at the moment and climbing). 
> 
> For grins I explicitly set the mapObj to None in  the mapserver layer code 
> after
> a tile is generated and while memory use is still sky high I've generated 
> 3,000
> tiles without a segfault.
> 
>> Regards,
> 
> Steve
> 
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