I just tried to compile a relatively small tile and got an out of memory error from Java! Normally when the tiles get too large, there are error messages from mkgmap. So I investigated a little bit and found out that the tile in question contained a huge number of <tag>s. The number of tags is ten times the number of nodes in the file. Is it possible that all these tags filled up my memory? Here's a list of the most frequently occuring tags: k='kms:parish_name' k='kms:parish_no' k='kms:city_name' k='kms:county_name' k='kms:county_no' k='kms:house_no' k='kms:last_updated' k='kms:municipality_name' k='kms:municipality_no' k='kms:street_name' k='kms:street_no' k='kms:zip_name' k='kms:zip_no' k='addr:housenumber' k='addr:street' k='addr:city' k='addr:postcode' k='source' And here's the Exception: Exception in thread "main" java.lang.OutOfMemoryError: Java heap space at java.util.Arrays.copyOfRange(Arrays.java:3209) at java.lang.String.<init>(String.java:216) at com.sun.org.apache.xerces.internal.xni.XMLString.toString(XMLString.j ava:185) at com.sun.org.apache.xerces.internal.util.XMLAttributesImpl.getValue(XM LAttributesImpl.java:557) at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser$Attribut esProxy.getValue(AbstractSAXParser.java:2323) at uk.me.parabola.mkgmap.reader.osm.xml.Osm5XmlHandler.startInNode(Osm5X mlHandler.java:178) at uk.me.parabola.mkgmap.reader.osm.xml.Osm5XmlHandler.startElement(Osm5 XmlHandler.java:136) at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.startEle ment(AbstractSAXParser.java:501) at com.sun.org.apache.xerces.internal.parsers.AbstractXMLDocumentParser. emptyElement(AbstractXMLDocumentParser.java:179) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImp l.scanStartElement(XMLDocumentFragmentScannerImpl.java:1339) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImp l$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:2747) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(X MLDocumentScannerImpl.java:648) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImp l.scanDocument(XMLDocumentFragmentScannerImpl.java:510) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(X ML11Configuration.java:807) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(X ML11Configuration.java:737) at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser. java:107) at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(Ab stractSAXParser.java:1205) at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.p arse(SAXParserImpl.java:522) at javax.xml.parsers.SAXParser.parse(SAXParser.java:395) at javax.xml.parsers.SAXParser.parse(SAXParser.java:198) at uk.me.parabola.mkgmap.reader.osm.xml.Osm5MapDataSource.load(Osm5MapDa taSource.java:78) at uk.me.parabola.mkgmap.main.MapMaker.loadFromFile(MapMaker.java:134) at uk.me.parabola.mkgmap.main.MapMaker.makeMap(MapMaker.java:51) at uk.me.parabola.mkgmap.main.Main.processFilename(Main.java:150) at uk.me.parabola.mkgmap.CommandArgs$Filename.processArg(CommandArgs.jav a:329) at uk.me.parabola.mkgmap.CommandArgs.readArgs(CommandArgs.java:119) at uk.me.parabola.mkgmap.main.Main.main(Main.java:91) -Wolfgang