<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Fri, Oct 27, 2017 at 4:14 PM, Even Rouault <span dir="ltr"><<a href="mailto:even.rouault@spatialys.com" target="_blank">even.rouault@spatialys.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><u></u>
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<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">Peter,</p><span class="">
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"> </p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">> I'm using MapServer-7.0.6 built with GDAL-2.2.2.  Is VSI_CACHE_SIZE the</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">> cache size per process? per file handle?</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"> </p>
</span><p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">Per-file handle :</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">"""</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">The default size of caching for each file is 25 MB, and</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">can be controlled with the VSI_CACHE_SIZE configuration option (value in bytes).</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">Content in that cache is discarded when the file handle is closed.</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">"""</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">( <a href="http://gdal.org/gdal_virtual_file_systems.html#gdal_virtual_file_systems_vsicache" target="_blank">http://gdal.org/gdal_virtual_<wbr>file_systems.html#gdal_<wbr>virtual_file_systems_vsicache</a> )</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"> </p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">So with CLOSE_CONNECTION=DEFER, what you observed is logical. </p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">CLOSE_CONNECTION=DEFER could probably be improved with a least recently used cache to maintain</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">the maximum number of simultaneously opened datasets to a reasonable amount.</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"> </p></div></blockquote><div><br></div><div>Ah, thanks Even!  I should have read the docs more carefully!</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="font-family:'Sans Serif';font-size:9pt;font-weight:400;font-style:normal">
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">Alternatively with GDAL trunk, for /vsicurl/ and related file systems, you can also</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">tune a global cache</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">"""</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">In addition, a global least-recently-used cache of 16 MB shared among all</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">downloaded content is enabled by default, and content in it may be reused</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">after a file handle has been closed and reopen. Starting with GDAL 2.3, the</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">size of this global LRU cache can be modified by setting the configuration</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">option CPL_VSIL_CURL_CACHE_SIZE (in bytes).</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">"""</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px">( <a href="http://gdal.org/gdal_virtual_file_systems.html#gdal_virtual_file_systems_vsicurl" target="_blank">http://gdal.org/gdal_virtual_<wbr>file_systems.html#gdal_<wbr>virtual_file_systems_vsicurl</a> )</p>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><br></p></div></blockquote><div><br></div><div>Nice, this will be helpful!</div><div><br></div><div>Thanks again,</div><div>Pete <br></div></div>
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