The virtual memory size of calibre-server is very high: 2 GB. That is equal to the complete physical memory. Take a look at the output of memstat below.
Could it be that there is a problem with the CPU and the OS? The CPU is an Intel N570 Atom Processor. "Max. Memory Size" is 2 GB. Therefore it makes no sense to use additional swap space (except for hibernation).
Intel Atom Processor N570
Another strange behavior is loading a lot of X-related libraries, but X is not running.
Code:
2394708k: PID 2047 (/opt/calibre-1.41/bin/calibre-server)
39168k( 0k): /opt/calibre-1.41/lib/libicudata.so.49 2047 2053 2047 2053 2047 2053
29324k( 21988k): /opt/calibre-1.41/lib/libQtWebKit.so.4 2047 2053 2047 2053 2047 2053
15616k( 10944k): /opt/calibre-1.41/lib/libQtGui.so.4 2047 2053 2047 2053 2047 2053 2047 2053
12996k( 6620k): /opt/calibre-1.41/lib/python2.7/site-packages/PyQt4/QtGui.so 2047 2053 2047 2053 2047 2053
8940k( 4348k): /opt/calibre-1.41/lib/libQtXmlPatterns.so.4 2047 2053 2047 2053 2047 2053 2047 2053
7140k( 2948k): /opt/calibre-1.41/lib/libQtCore.so.4 2047 2053 2047 2053 2047 2053
7016k( 2136k): /opt/calibre-1.41/lib/python2.7/site-packages/PyQt4/QtCore.so 2047 2053 2047 2053 2047 2053 2047 2053
6972k( 2036k): /opt/calibre-1.41/lib/libMagickCore.so.5 2047 2053 2047 2053 2047 2053
6320k( 2120k): /opt/calibre-1.41/lib/libicui18n.so.49 2047 2053 2047 2053 2047 2053 2047 2053
6080k( 1688k): /opt/calibre-1.41/lib/libcrypto.so.1.0.0 2047 2053 2047 2053 2047 2053 2047 2053
6080k( 1480k): /opt/calibre-1.41/lib/libpython2.7.so.1.0 2047 2053 2047 2053 2047 2053
5740k( 1220k): /opt/calibre-1.41/lib/python2.7/site-packages/lxml/etree.so 2047 2053 2047 2053 2047 2053
5700k( 1460k): /opt/calibre-1.41/lib/libicuuc.so.49 2047 2053 2047 2053 2047 2053
5476k( 1316k): /opt/calibre-1.41/lib/libQtNetwork.so.4 2047 2053 2047 2053 2047 2053
5472k( 1304k): /opt/calibre-1.41/lib/libxml2.so.2 2047 2053 2047 2053 2047 2053 2047 2053
5248k( 1120k): /opt/calibre-1.41/lib/libMagickWand.so.5 2047 2053 2047 2053 2047 2053
5240k( 1128k): /opt/calibre-1.41/lib/libglib-2.0.so.0 2047 2053 2047 2053 2047 2053
5136k( 968k): /opt/calibre-1.41/lib/libstdc++.so.6 2047 2053 2047 2053 2047 2053
4940k( 612k): /opt/calibre-1.41/lib/python2.7/site-packages/PyQt4/QtNetwork.so 2047 2053 2047 2053 2047 2053
4848k( 600k): /opt/calibre-1.41/lib/python2.7/lib-dynload/unicodedata.so 2047 2053 2047 2053 2047 2053
4824k( 696k): /opt/calibre-1.41/lib/libsqlite3.so.0 2047 2053 2047 2053 2047 2053 2047 2053
4616k( 504k): /opt/calibre-1.41/lib/libQtDBus.so.4 2047 2053 2047 2053 2047 2053 2047 2053
4612k( 380k): /opt/calibre-1.41/lib/python2.7/site-packages/PyQt4/QtWebKit.so 2047 2053 2047 2053 2047 2053 2047 2053
4588k( 460k): /opt/calibre-1.41/lib/libgcrypt.so.11 2047 2053 2047 2053 2047 2053
4560k( 432k): /opt/calibre-1.41/lib/libtiff.so.5 2047 2053 2047 2053 2047 2053
4552k( 384k): /opt/calibre-1.41/lib/libssl.so.1.0.0 2047 2053 2047 2053 2047 2053 2047 2053
4480k( 360k): /opt/calibre-1.41/lib/libQtSvg.so.4 2047 2053 2047 2053 2047 2053
4480k( 272k): /opt/calibre-1.41/lib/python2.7/site-packages/PyQt4/QtXml.so 2047 2053 2047 2053 2047 2053
4476k( 276k): /opt/calibre-1.41/lib/python2.7/site-packages/PyQt4/QtDesigner.so 2047 2053 2047 2053 2047 2053
4428k( 244k): /opt/calibre-1.41/lib/python2.7/site-packages/PyQt4/QtOpenGL.so 2047 2053 2047 2053 2047 2053
4404k( 276k): /opt/calibre-1.41/lib/liblcms2.so.2 2047 2053 2047 2053 2047 2053
4404k( 268k): /opt/calibre-1.41/lib/python2.7/site-packages/apsw.so 2047 2053 2047 2053 2047 2053
4396k( 276k): /opt/calibre-1.41/lib/libQtXml.so.4 2047 2053 2047 2053 2047 2053
4364k( 188k): /opt/calibre-1.41/lib/python2.7/site-packages/PyQt4/QtDBus.so 2047 2053 2047 2053 2047 2053
4360k( 248k): /opt/calibre-1.41/lib/libjpeg.so.8 2047 2053 2047 2053 2047 2053
4348k( 236k): /opt/calibre-1.41/lib/libdbus-1.so.3 2047 2053 2047 2053 2047 2053
4328k( 224k): /opt/calibre-1.41/lib/libxslt.so.1 2047 2053 2047 2053 2047 2053
4296k( 144k): /opt/calibre-1.41/lib/python2.7/site-packages/PyQt4/QtXmlPatterns.so 2047 2053 2047 2053 2047 2053
4296k( 112k): /opt/calibre-1.41/lib/python2.7/lib-dynload/_io.so 2047 2053 2047 2053 2047 2053
4272k( 152k): /opt/calibre-1.41/lib/libexpat.so.1 2047 2053 2047 2053 2047 2053
4256k( 152k): /opt/calibre-1.41/lib/libpng14.so.14 2047 2053 2047 2053 2047 2053
4240k( 104k): /opt/calibre-1.41/lib/python2.7/lib-dynload/_ctypes.so 2047 2053 2047 2053 2047 2053
4224k( 112k): /opt/calibre-1.41/lib/python2.7/site-packages/sip.so 2047 2053 2047 2053 2047 2053
4200k( 80k): /opt/calibre-1.41/lib/python2.7/site-packages/PyQt4/QtSvg.so 2047 2053 2047 2053 2047 2053
4196k( 68k): /opt/calibre-1.41/lib/python2.7/lib-dynload/datetime.so 2047 2053 2047 2053 2047 2053
4192k( 80k): /opt/calibre-1.41/lib/libz.so.1 2047 2053 2047 2053 2047 2053
4192k( 56k): /opt/calibre-1.41/lib/python2.7/lib-dynload/_socket.so 2047 2053 2047 2053 2047 2053
4188k( 76k): /opt/calibre-1.41/lib/libexslt.so.0 2047 2053 2047 2053 2047 2053
4176k( 72k): /opt/calibre-1.41/lib/python2.7/lib-dynload/cPickle.so 2047 2053 2047 2053 2047 2053
4176k( 40k): /opt/calibre-1.41/lib/python2.7/lib-dynload/itertools.so 2047 2053 2047 2053 2047 2053
4164k( 60k): /opt/calibre-1.41/lib/libbz2.so.1 2047 2053 2047 2053 2047 2053
4160k( 48k): /opt/calibre-1.41/lib/libicuio.so.49 2047 2053 2047 2053 2047 2053 2047 2053
4160k( 40k): /opt/calibre-1.41/lib/python2.7/lib-dynload/pyexpat.so 2047 2053 2047 2053 2047 2053
4156k( 52k): /opt/calibre-1.41/lib/python2.7/site-packages/calibre/plugins/magick.so 2047 2053 2047 2053 2047 2053
4144k( 40k): /opt/calibre-1.41/lib/python2.7/lib-dynload/_elementtree.so 2047 2053 2047 2053 2047 2053
4144k( 32k): /opt/calibre-1.41/lib/python2.7/lib-dynload/operator.so 2047 2053 2047 2053 2047 2053
4144k( 32k): /opt/calibre-1.41/lib/python2.7/lib-dynload/math.so 2047 2053 2047 2053 2047 2053
4144k( 32k): /opt/calibre-1.41/lib/python2.7/lib-dynload/array.so 2047 2053 2047 2053 2047 2053
4140k( 28k): /opt/calibre-1.41/lib/python2.7/site-packages/PyQt4/QtTest.so 2047 2053 2047 2053 2047 2053
4140k( 28k): /opt/calibre-1.41/lib/python2.7/site-packages/calibre/plugins/icu.so 2047 2053 2047 2053 2047 2053
4140k( 28k): /opt/calibre-1.41/lib/python2.7/lib-dynload/_struct.so 2047 2053 2047 2053 2047 2053
4140k( 20k): /opt/calibre-1.41/lib/python2.7/lib-dynload/_csv.so 2047 2053 2047 2053 2047 2053
4136k( 32k): /opt/calibre-1.41/lib/python2.7/lib-dynload/_ssl.so 2047 2053 2047 2053 2047 2053
4136k( 32k): /opt/calibre-1.41/lib/python2.7/lib-dynload/_json.so 2047 2053 2047 2053 2047 2053
4136k( 24k): /opt/calibre-1.41/lib/python2.7/lib-dynload/_collections.so 2047 2053 2047 2053 2047 2053
4132k( 28k): /opt/calibre-1.41/lib/libffi.so.4 2047 2053 2047 2053 2047 2053
4132k( 20k): /opt/calibre-1.41/lib/python2.7/lib-dynload/zlib.so 2047 2053 2047 2053 2047 2053
4132k( 20k): /opt/calibre-1.41/lib/python2.7/lib-dynload/strop.so 2047 2053 2047 2053 2047 2053
4132k( 20k): /opt/calibre-1.41/lib/python2.7/lib-dynload/select.so 2047 2053 2047 2053 2047 2053
4128k( 16k): /opt/calibre-1.41/lib/python2.7/lib-dynload/time.so 2047 2053 2047 2053 2047 2053
4128k( 16k): /opt/calibre-1.41/lib/python2.7/lib-dynload/cStringIO.so 2047 2053 2047 2053 2047 2053
4124k( 12k): /opt/calibre-1.41/lib/python2.7/lib-dynload/_heapq.so 2047 2053 2047 2053 2047 2053
4120k( 16k): /opt/calibre-1.41/lib/python2.7/lib-dynload/_locale.so 2047 2053 2047 2053 2047 2053
4120k( 16k): /opt/calibre-1.41/lib/python2.7/lib-dynload/binascii.so 2047 2053 2047 2053 2047 2053
4116k( 12k): /opt/calibre-1.41/lib/python2.7/lib-dynload/_random.so 2047 2053 2047 2053 2047 2053
4116k( 12k): /opt/calibre-1.41/lib/python2.7/lib-dynload/_hashlib.so 2047 2053 2047 2053 2047 2053
4116k( 12k): /opt/calibre-1.41/lib/python2.7/lib-dynload/_functools.so 2047 2053 2047 2053 2047 2053
4116k( 12k): /opt/calibre-1.41/lib/python2.7/lib-dynload/fcntl.so 2047 2053 2047 2053 2047 2053
4116k( 12k): /opt/calibre-1.41/lib/libgpg-error.so.0 2047 2053 2047 2053 2047 2053
4116k( 12k): /opt/calibre-1.41/lib/libcalibre-launcher.so 2047 2053 2047 2053 2047 2053
4112k( 8k): /opt/calibre-1.41/lib/python2.7/site-packages/calibre/plugins/speedup.so 2047 2053 2047 2053 2047 2053
4112k( 8k): /opt/calibre-1.41/lib/python2.7/lib-dynload/grp.so 2047 2053 2047 2053 2047 2053
4112k( 8k): /opt/calibre-1.41/lib/python2.7/lib-dynload/_bisect.so 2047 2053 2047 2053 2047 2053
4108k( 4k): /opt/calibre-1.41/lib/python2.7/site-packages/PyQt4/Qt.so 2047 2053 2047 2053 2047 2053
4108k( 4k): /opt/calibre-1.41/lib/python2.7/lib-dynload/future_builtins.so 2047 2053 2047 2053 2047 2053
2096k( 40k): /opt/calibre-1.41/lib/ImageMagick-6.7.6/modules-Q16/coders/jpeg.so 2047
20k( 4k): /opt/calibre-1.41/bin/calibre-server 2047 2053 2047 2053 2047 2053