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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-AU link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>hi,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I would be prepared to contribute to such a facility in GDAL if it permitted multiple simultaneous writes (to different bands / tiles)<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>pk<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'> Jan Hartmann [mailto:j.l.h.hartmann@uva.nl] <br><b>Sent:</b> Friday, 11 January 2013 5:43 PM<br><b>To:</b> Frank Warmerdam<br><b>Cc:</b> Kennedy, Paul; gdal dev<br><b>Subject:</b> Re: [gdal-dev] does gdal support multiple simultaneous writers to raster<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'>I'v tried this in a Cloud environment with multiple VMs writing to the same shared file location. I didn't use tiles, so the results where negative. It would be a great asset for Cloud environments, however. Is it in principle possible to build such a facility into GDAL, and if yes, what kind of funding would it require?<br><br>Jan<o:p></o:p></p><div><p class=MsoNormal>On 01/11/2013 02:32 AM, Frank Warmerdam wrote:<o:p></o:p></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><pre>Paul,<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>Generally speaking - no - GDAL does not now support multi-threaded<o:p></o:p></pre><pre>writing. Part of this is due to the way stuff gets write-flushed out<o:p></o:p></pre><pre>of the block cache and partly it is just that none of GDAL supports<o:p></o:p></pre><pre>multiple threading on a single dataset.<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>This statement is based on the assumption it is all in one process.<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>If you want to run different processes with the output to a<o:p></o:p></pre><pre>pre-existing "fixed location" format like uncompressed GeoTIFF with<o:p></o:p></pre><pre>tiles that is all preinitialized to some real value then you could<o:p></o:p></pre><pre>certainly use one output file for many writers as long as case is<o:p></o:p></pre><pre>taken to not have multiple processes write to the same tile. But GDAL<o:p></o:p></pre><pre>isn't doing anything to make this easy.<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>Best regards,<o:p></o:p></pre><pre>Frank<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>On Thu, Jan 10, 2013 at 4:12 PM, Kennedy, Paul <a href="mailto:P.Kennedy@fugro.com.au"><P.Kennedy@fugro.com.au></a> wrote:<o:p></o:p></pre><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><pre>I am looking to parallelize a long duration gridding process, and was<o:p></o:p></pre><pre>wondering if GDAL can support multiple simultaneous writers from processess?<o:p></o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre>I am not sure if any of the underlying raster formats support this?<o:p></o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre>thanks in advance.<o:p></o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre>regards<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>pk<o:p></o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre>_______________________________________________<o:p></o:p></pre><pre>gdal-dev mailing list<o:p></o:p></pre><pre><a href="mailto:gdal-dev@lists.osgeo.org">gdal-dev@lists.osgeo.org</a><o:p></o:p></pre><pre><a href="http://lists.osgeo.org/mailman/listinfo/gdal-dev">http://lists.osgeo.org/mailman/listinfo/gdal-dev</a><o:p></o:p></pre></blockquote><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre></blockquote><p class=MsoNormal><o:p> </o:p></p></div></body></html>