<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<p>Sorry I don't know enough about virtual memory implementation to
comment.</p>
<p>The only software I am sufficiently familiar with from experience
is Gimp, which has the setting where you can specify the size of
the tile cache. So for example I have a tile cache set to 200 GB.
It starts with physical RAM then pushes into the swap space. <br>
</p>
<p>I can monitor the resource use of the system with a widget
displayed on the panel on the computer. This shows CPU use, memory
and swap space use. From there I can watch the resource use of the
system while doing things. I can compare the resource usage being
displayed for the system with the Gimp dashboard. <br>
</p>
<p>The assumption for me is that the operating system, in theory,
presents a virtual memory model to applications, whereby the
actual physical implementation is abstracted, such that when an
application makes a request for more memory allocated, it is
essentially transparent where the information is actually
physically stored. Maybe that is not accurate?<br>
</p>
On 27/01/20 8:18 pm, Bo Victor Thomsen wrote:<br>
<blockquote type="cite"
cite="mid:c847c6d6-8133-a27e-a0d7-1d04ff0cf669@gmail.com">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<p>Hi Patrick -</p>
<p>Swap space is an internal component the underlying operating
system (OS) uses for handling memory request that exceeds the
ram resources of the computer. A normal user program like QGIS
has no "knowledge" about this facility and can't directly
manipulate the swap system.</p>
<p>As Jonathan describes, "swap" space for for other program is
temporary file storage, usually placed in a specific directory
(in windows designated by the environment variable %TEMP%). QGIS
uses this directory too.</p>
<p>A QGIS crash can be caused by running out of memory resources
and/or temp file storage. However, that is result of a bad setup
of your operating system, which can limit how much swap space,
that can be allocated to memory hungry programs and the size of
hard-disk used for swap space and/or temp storage</p>
<p>So what to do:<br>
</p>
<ol>
<li>Check memory consumption when using QGIS. Is it really using
all the ram - memory and starting to swap ?</li>
<li>Check the setup of the swap space parameters. It it using a
hard-disk which is running out of storage space.</li>
<li>Check the setup of the temp storage parameters. It it using
a hard-disk which is running out of storage space ? Are the
user allowed to allocate enough storage?<br>
</li>
</ol>
<p>(I can't be more specific not knowing the operating system you
use)<br>
</p>
<p>If the above checks out OK and you still have issues with QGIS
crashing..<br>
</p>
<p>The shift from QGIS 2.x to QGIS 3.x meant a complete change of
the underlying graphics subsystem QT from ver 4.x to ver. 5.x
(and a huge amount of other changes). <br>
</p>
<p>One or more of those changes might cause a failure as you
described. However, you have to check the above and then write
an error issue (<a class="moz-txt-link-freetext"
href="https://github.com/qgis/QGIS/issues"
moz-do-not-send="true">https://github.com/qgis/QGIS/issues</a>)
where you describe error messages, your specific setup like
operating system and version, QGIS version and - if possible -
test-data and project to replicate the issue. <br>
</p>
<pre class="moz-signature" cols="72">--
Med venlig hilsen / Kind regards
Bo Victor Thomsen</pre>
<br>
</blockquote>
</body>
</html>