Hi All,
I am using geotools to generate images based on a remote WMS, and a local WFS.
To increase throughput, I am attempted to make the software multithreaded (in a
non application server environment).
However I think I am getting deadlock (well maybe not deadlock, but the threads
seem to be stuck waiting for one of the threads waiting to download XML schemas
over the internet).
On initial startup of WebMapServer object (each thread keeps it's own instance
of a WebMapServer for performance - downloading XML schemas in particularly
time consuming) it seems to download lots of XML schemas from the
getCapabilities document for the WMS.
Ideally I would like to cache these on the file system, is this possible, if so
how? This may alleviate the problem in terms of time (it seems to take a long
time) taken to download the various XML schemas. But would be preferential
anyway to reduce startup time.
Secondly each WebMapServer object seems to be waiting on a lock on
org.geotools.xml.SchemaFactory.getInstance which is locked by one of the
WebMapServer objects.
Does this have to be the case, or can I remove this area as a bottle neck? Is
this is a bug? I can see that SchemaFactory.getInstance seems to be intended to
be thread safe.
I have pasted the stack of some of the example threads below, and any
help/advice would be very much appreciated!!
Thanks
Norman
THREAD with LOCK
"Piper Processor 3" prio=1 tid=0x0966e9d0 nid=0x3b4f runnable
[0xe7c8f000..0xe7c90130]
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.read(SocketInputStream.java:129)
at java.io.BufferedInputStream.fill(BufferedInputStream.java:218)
at java.io.BufferedInputStream.read1(BufferedInputStream.java:256)
at java.io.BufferedInputStream.read(BufferedInputStream.java:313)
- locked <0xeabe3e70> (a java.io.BufferedInputStream)
at sun.net.www.http.HttpClient.parseHTTPHeader(HttpClient.java:606)
at sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:554)
at
sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:936)
- locked <0xeabe2480> (a sun.net.www.protocol.http.HttpURLConnection)
at org.apache.xerces.impl.XMLEntityManager.setupCurrentEntity(Unknown
Source)
at
org.apache.xerces.impl.XMLVersionDetector.determineDocVersion(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
at org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown
Source)
at javax.xml.parsers.SAXParser.parse(SAXParser.java:375)
at javax.xml.parsers.SAXParser.parse(SAXParser.java:255)
at
org.geotools.xml.SchemaFactory.getRealInstance(SchemaFactory.java:305)
- locked <0xeb52acf0> (a org.geotools.xml.SchemaFactory)
at org.geotools.xml.SchemaFactory.getInstance(SchemaFactory.java:265)
- locked <0xef884168> (a java.lang.Class)
at
org.geotools.xml.handlers.xsi.SchemaHandler.compress(SchemaHandler.java:430)
at
org.geotools.xml.handlers.xsi.RootHandler.getSchema(RootHandler.java:117)
at org.geotools.xml.XSISAXHandler.getSchema(XSISAXHandler.java:257)
at
org.geotools.xml.SchemaFactory.getRealInstance(SchemaFactory.java:310)
- locked <0xeb52acf0> (a org.geotools.xml.SchemaFactory)
at org.geotools.xml.SchemaFactory.getInstance(SchemaFactory.java:265)
- locked <0xef884168> (a java.lang.Class)
at
org.geotools.xml.handlers.xsi.SchemaHandler.compress(SchemaHandler.java:385)
at
org.geotools.xml.handlers.xsi.RootHandler.getSchema(RootHandler.java:117)
at org.geotools.xml.XSISAXHandler.getSchema(XSISAXHandler.java:257)
at
org.geotools.xml.SchemaFactory.getRealInstance(SchemaFactory.java:310)
- locked <0xeb52acf0> (a org.geotools.xml.SchemaFactory)
at org.geotools.xml.SchemaFactory.getInstance(SchemaFactory.java:265)
- locked <0xef884168> (a java.lang.Class)
at
org.geotools.xml.handlers.xsi.SchemaHandler.compress(SchemaHandler.java:430)
at
org.geotools.xml.handlers.xsi.RootHandler.getSchema(RootHandler.java:117)
at org.geotools.xml.XSISAXHandler.getSchema(XSISAXHandler.java:257)
at
org.geotools.xml.SchemaFactory.getRealInstance(SchemaFactory.java:310)
- locked <0xeb52acf0> (a org.geotools.xml.SchemaFactory)
at org.geotools.xml.SchemaFactory.getInstance(SchemaFactory.java:265)
- locked <0xef884168> (a java.lang.Class)
at
org.geotools.xml.handlers.ElementHandlerFactory.startPrefixMapping(ElementHandlerFactory.java:87)
at org.geotools.xml.XMLSAXHandler.startElement(XMLSAXHandler.java:370)
at org.apache.xerces.parsers.AbstractSAXParser.startElement(Unknown
Source)
at
org.apache.xerces.impl.XMLNSDocumentScannerImpl.scanStartElement(Unknown Source)
at
org.apache.xerces.impl.XMLNSDocumentScannerImpl$NSContentDispatcher.scanRootElementHook(Unknown
Source)
at
org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(Unknown
Source)
at
org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown
Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
at org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown
Source)
at javax.xml.parsers.SAXParser.parse(SAXParser.java:375)
at javax.xml.parsers.SAXParser.parse(SAXParser.java:176)
at
org.geotools.xml.DocumentFactory.getInstance(DocumentFactory.java:133)
at
org.geotools.data.wms.response.WMSGetCapabilitiesResponse.<init>(WMSGetCapabilitiesResponse.java:54)
at
org.geotools.data.wms.WMS1_0_0$GetCapsRequest.createResponse(WMS1_0_0.java:231)
at
org.geotools.data.ows.AbstractOpenWebService.internalIssueRequest(AbstractOpenWebService.java:440)
at
org.geotools.data.wms.WebMapServer.issueRequest(WebMapServer.java:405)
at
org.geotools.data.ows.AbstractOpenWebService.negotiateVersion(AbstractOpenWebService.java:240)
at
org.geotools.data.ows.AbstractOpenWebService.<init>(AbstractOpenWebService.java:95)
at
org.geotools.data.ows.AbstractOpenWebService.<init>(AbstractOpenWebService.java:81)
at org.geotools.data.wms.WebMapServer.<init>(WebMapServer.java:368)
THREADS without lock....
"Piper Processor 2" prio=1 tid=0x0964bf50 nid=0x3b4e waiting for monitor entry
[0xe7d10000..0xe7d10fb0]
at org.geotools.xml.SchemaFactory.getInstance(SchemaFactory.java:265)
- waiting to lock <0xef884168> (a java.lang.Class)
at
org.geotools.xml.handlers.ElementHandlerFactory.startPrefixMapping(ElementHandlerFactory.java:87)
at org.geotools.xml.XMLSAXHandler.startElement(XMLSAXHandler.java:370)
at org.apache.xerces.parsers.AbstractSAXParser.startElement(Unknown
Source)
at
org.apache.xerces.impl.XMLNSDocumentScannerImpl.scanStartElement(Unknown Source)
at
org.apache.xerces.impl.XMLNSDocumentScannerImpl$NSContentDispatcher.scanRootElementHook(Unknown
Source)
at
org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(Unknown
Source)
at
org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown
Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
at org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown
Source)
at javax.xml.parsers.SAXParser.parse(SAXParser.java:375)
at javax.xml.parsers.SAXParser.parse(SAXParser.java:176)
at
org.geotools.xml.DocumentFactory.getInstance(DocumentFactory.java:133)
at
org.geotools.data.wms.response.WMSGetCapabilitiesResponse.<init>(WMSGetCapabilitiesResponse.java:54)
at
org.geotools.data.wms.WMS1_0_0$GetCapsRequest.createResponse(WMS1_0_0.java:231)
at
org.geotools.data.ows.AbstractOpenWebService.internalIssueRequest(AbstractOpenWebService.java:440)
at
org.geotools.data.wms.WebMapServer.issueRequest(WebMapServer.java:405)
at
org.geotools.data.ows.AbstractOpenWebService.negotiateVersion(AbstractOpenWebService.java:240)
at
org.geotools.data.ows.AbstractOpenWebService.<init>(AbstractOpenWebService.java:95)
at
org.geotools.data.ows.AbstractOpenWebService.<init>(AbstractOpenWebService.java:81)
at org.geotools.data.wms.WebMapServer.<init>(WebMapServer.java:368)
"Piper Processor 1" prio=1 tid=0x0964bdc8 nid=0x3b4d waiting for monitor entry
[0xe7d91000..0xe7d92030]
at org.geotools.xml.SchemaFactory.getInstance(SchemaFactory.java:208)
- waiting to lock <0xef884168> (a java.lang.Class)
at
org.geotools.xml.handlers.ElementHandlerFactory.startPrefixMapping(ElementHandlerFactory.java:115)
at org.geotools.xml.XMLSAXHandler.startElement(XMLSAXHandler.java:383)
at org.apache.xerces.parsers.AbstractSAXParser.startElement(Unknown
Source)
at
org.apache.xerces.parsers.AbstractXMLDocumentParser.emptyElement(Unknown Source)
at
org.apache.xerces.impl.XMLNSDocumentScannerImpl.scanStartElement(Unknown Source)
at
org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(Unknown
Source)
at
org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown
Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
at org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown
Source)
at javax.xml.parsers.SAXParser.parse(SAXParser.java:375)
at javax.xml.parsers.SAXParser.parse(SAXParser.java:176)
at
org.geotools.xml.DocumentFactory.getInstance(DocumentFactory.java:133)
at
org.geotools.data.wms.response.WMSGetCapabilitiesResponse.<init>(WMSGetCapabilitiesResponse.java:54)
at
org.geotools.data.wms.WMS1_0_0$GetCapsRequest.createResponse(WMS1_0_0.java:231)
at
org.geotools.data.ows.AbstractOpenWebService.internalIssueRequest(AbstractOpenWebService.java:440)
at
org.geotools.data.wms.WebMapServer.issueRequest(WebMapServer.java:405)
at
org.geotools.data.ows.AbstractOpenWebService.negotiateVersion(AbstractOpenWebService.java:240)
at
org.geotools.data.ows.AbstractOpenWebService.<init>(AbstractOpenWebService.java:95)
at
org.geotools.data.ows.AbstractOpenWebService.<init>(AbstractOpenWebService.java:81)
at org.geotools.data.wms.WebMapServer.<init>(WebMapServer.java:368)
at
com.bt.mbe.processing.PIPERProcessor.getWMSLayer(PIPERProcessor.java:369)
at
com.bt.mbe.processing.PIPERProcessor.processItem(PIPERProcessor.java:269)
at com.bt.mbe.processing.PIPERProcessor.run(PIPERProcessor.java:211)
at java.lang.Thread.run(Thread.java:595)
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