Operating System: All
Platform: All

It works for JSON, but hangs for XML, so I do not think that this issue is OpenFlowPlugin related at all. Maybe it is restconf related?

We need karaf.log and probably a thread dump.

Also, what does 'controller hangs' mean?

I just tried this, the REST request hangs and I can perform other REST requests but the controller goes crazy in CPU even when I cancel the original request.

There is nothing out of normal in karaf log and I attach the thread dump.

Attachment thread_dump.txt has been added with description: Thread dump

"qtp181445460-221" #221 prio=5 os_prio=0 tid=0x00007f18241d3000 nid=0x175c runnable [0x00007f17b1ee6000]
java.lang.Thread.State: RUNNABLE
at java.lang.String.intern(Native Method)
at com.sun.org.apache.xerces.internal.util.SymbolTable$Entry.<init>(SymbolTable.java:448)
at com.sun.org.apache.xerces.internal.util.SymbolTable.addSymbol0(SymbolTable.java:195)
at com.sun.org.apache.xerces.internal.util.SymbolTable.addSymbol(SymbolTable.java:176)
at com.sun.xml.internal.stream.writers.XMLStreamWriterImpl$NamespaceContextImpl.getNamespaceURI(XMLStreamWriterImpl.java:2051)
at org.opendaylight.yangtools.yang.data.codec.xml.RandomPrefix.alreadyUsedPrefix(RandomPrefix.java:66)
at org.opendaylight.yangtools.yang.data.codec.xml.RandomPrefix.encodePrefix(RandomPrefix.java:55)
at org.opendaylight.yangtools.yang.data.codec.xml.RandomPrefixInstanceIdentifierSerializer.prefixForNamespace(RandomPrefixInstanceIdentifierSerializer.java:34)
at org.opendaylight.yangtools.yang.data.util.AbstractNamespaceCodec.appendQName(AbstractNamespaceCodec.java:45)
at org.opendaylight.yangtools.yang.data.util.AbstractStringInstanceIdentifierCodec.serialize(AbstractStringInstanceIdentifierCodec.java:51)
at org.opendaylight.yangtools.yang.data.codec.xml.SchemaAwareXMLStreamWriterUtils.writeInstanceIdentifier(SchemaAwareXMLStreamWriterUtils.java:41)
at org.opendaylight.yangtools.yang.data.codec.xml.XMLStreamWriterUtils.write(XMLStreamWriterUtils.java:149)
at org.opendaylight.yangtools.yang.data.codec.xml.XMLStreamWriterUtils.writeValue(XMLStreamWriterUtils.java:103)
at org.opendaylight.yangtools.yang.data.codec.xml.XMLStreamWriterUtils.writeValue(XMLStreamWriterUtils.java:79)
at org.opendaylight.yangtools.yang.data.codec.xml.SchemaAwareXMLStreamNormalizedNodeStreamWriter.writeValue(SchemaAwareXMLStreamNormalizedNodeStreamWriter.java:51)
at org.opendaylight.yangtools.yang.data.codec.xml.SchemaAwareXMLStreamNormalizedNodeStreamWriter.writeValue(SchemaAwareXMLStreamNormalizedNodeStreamWriter.java:32)
at org.opendaylight.yangtools.yang.data.codec.xml.XMLStreamNormalizedNodeStreamWriter.writeElement(XMLStreamNormalizedNodeStreamWriter.java:179)
at org.opendaylight.yangtools.yang.data.codec.xml.SchemaAwareXMLStreamNormalizedNodeStreamWriter.leafNode(SchemaAwareXMLStreamNormalizedNodeStreamWriter.java:90)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessAsSimpleNode(NormalizedNodeWriter.java:145)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:101)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:169)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:223)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:97)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:169)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter$OrderedNormalizedNodeWriter.writeMapEntryNode(NormalizedNodeWriter.java:283)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:208)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:97)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:169)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:238)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:97)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:169)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter$OrderedNormalizedNodeWriter.writeMapEntryNode(NormalizedNodeWriter.java:283)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:208)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:97)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:169)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:238)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:97)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:169)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:195)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:97)
at org.opendaylight.netconf.sal.rest.impl.RestconfDelegatingNormalizedNodeWriter.write(RestconfDelegatingNormalizedNodeWriter.java:37)
at org.opendaylight.netconf.sal.rest.impl.RestconfDelegatingNormalizedNodeWriter.write(RestconfDelegatingNormalizedNodeWriter.java:19)
at org.opendaylight.netconf.sal.rest.impl.NormalizedNodeXmlBodyWriter.writeNormalizedNode(NormalizedNodeXmlBodyWriter.java:127)
at org.opendaylight.netconf.sal.rest.impl.NormalizedNodeXmlBodyWriter.writeTo(NormalizedNodeXmlBodyWriter.java:104)
at org.opendaylight.netconf.sal.rest.impl.NormalizedNodeXmlBodyWriter.writeTo(NormalizedNodeXmlBodyWriter.java:52)
at com.sun.jersey.spi.container.ContainerResponse.write(ContainerResponse.java:306)
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1479)
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1391)
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1381)
at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:416)
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:538)
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:716)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)

Looks like RandomPrefix incorrectly processes the result of NamespaceContext.getNamespaceURI().

In case it helps, here is the json output for the request that fais in XML:

{
"network-topology": {
"topology": [
{
"topology-id": "flow:1",
"node": [
{
"node-id": "openflow:1",
"opendaylight-topology-inventory:inventory-node-ref": "/opendaylight-inventory:nodes/opendaylight-inventory:node[opendaylight-inventory:id='openflow:1']",
"termination-point": [

,

]
}
]
}
]
}
}

This also may have to do with RESTCONF's use of namespace repairing. It should not be needing that, I think.

Maybe we should be checking the XMLWriter instance configuration?

after performed investigation I have suspicios that maybe this loop (https://github.com/opendaylight/yangtools/blob/master/yang/yang-data-impl/src/main/java/org/opendaylight/yangtools/yang/data/impl/codec/xml/RandomPrefix.java#L54) runs infinitely, but I am not sure yet...

master: https://git.opendaylight.org/gerrit/60736

This looks like a bug in JDK, as the return value does not seem to conform to javadoc (which states that for unbound prefixes an empty string should be returned).

In fact javax.xml.bind.DatatypeConverterImpl in jdk-1.8.0.131 on line 403 says:

uri = nsc.getNamespaceURI(prefix);
// uri can never be null according to javadoc,
// but some users reported that there are implementations that return null.
if (uri == null || uri.length() == 0) // crap. the NamespaceContext interface is broken.
// error: unbound prefix