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https://issues.apache.org/activemq/browse/CAMEL-2692?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=59225#action_59225
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Roland Knight commented on CAMEL-2692:
--------------------------------------
Yes, I am using the stock JDK 6 XML parser.
Turning debugging on reveals the underlying problem. It appears that Camel is
calling Document.importNode from multiple threads on the same Document causing
an ArrayIndexOutOfBounds error. This occurs in the converter and results in a
null value. The stack trace for this error is below:
Thread [Camel Thread 9 - Split] (Suspended (exception
ArrayIndexOutOfBoundsException))
Vector<E>.elementAt(int) line: 427
DeferredDocumentImpl.getNodeValueString(int, boolean) line: 1167
DeferredDocumentImpl.getNodeValueString(int) line: 1120
DeferredTextImpl.synchronizeData() line: 93 [local variables
unavailable]
DeferredTextImpl(CharacterDataImpl).getNodeValue() line: 88
DocumentImpl(CoreDocumentImpl).importNode(Node, boolean, boolean,
Hashtable) line: 1629
DocumentImpl(CoreDocumentImpl).importNode(Node, boolean, boolean,
Hashtable) line: 1742
DocumentImpl(CoreDocumentImpl).importNode(Node, boolean, boolean,
Hashtable) line: 1742
DocumentImpl(CoreDocumentImpl).importNode(Node, boolean) line: 1498
XmlConverter.toDOMDocument(Node) line: 572
NativeMethodAccessorImpl.invoke0(Method, Object, Object[]) line: not
available [native method]
NativeMethodAccessorImpl.invoke(Object, Object[]) line: 39
DelegatingMethodAccessorImpl.invoke(Object, Object[]) line: 25
Method.invoke(Object, Object...) line: 597
ObjectHelper.invokeMethod(Method, Object, Object...) line: 772
InstanceMethodTypeConverter.convertTo(Class<T>, Exchange, Object) line:
69
DefaultTypeConverter.doConvertTo(Class, Exchange, Object) line: 165
DefaultTypeConverter.convertTo(Class<T>, Exchange, Object) line: 91
DefaultMessage(MessageSupport).getBody(Class<T>, Object) line: 74
DefaultMessage(MessageSupport).getBody(Class<T>) line: 48
MoreoverTest$1$1.process(Exchange) line: 25
InstrumentationProcessor.process(Exchange) line: 67
TraceInterceptor(DelegateProcessor).processNext(Exchange) line: 53
TraceInterceptor(DelegateProcessor).proceed(Exchange) line: 82
TraceInterceptor.process(Exchange) line: 97
InstrumentationProcessor.process(Exchange) line: 67
DefaultErrorHandler(RedeliveryErrorHandler).processExchange(Exchange)
line: 177
DefaultErrorHandler(RedeliveryErrorHandler).processErrorHandler(Exchange,
RedeliveryErrorHandler$RedeliveryData) line: 143
DefaultErrorHandler(RedeliveryErrorHandler).process(Exchange) line: 88
DefaultErrorHandler.process(Exchange) line: 49
DefaultChannel.process(Exchange) line: 228
DefaultErrorHandler(RedeliveryErrorHandler).processExchange(Exchange)
line: 177
DefaultErrorHandler(RedeliveryErrorHandler).processErrorHandler(Exchange,
RedeliveryErrorHandler$RedeliveryData) line: 143
DefaultErrorHandler(RedeliveryErrorHandler).process(Exchange) line: 88
DefaultErrorHandler.process(Exchange) line: 49
Splitter(MulticastProcessor).doProcess(Processor, Processor, Exchange)
line: 278
MulticastProcessor.access$000(MulticastProcessor, Processor, Processor,
Exchange) line: 62
MulticastProcessor$1.call() line: 199
MulticastProcessor$1.call() line: 193
FutureTask$Sync.innerRun() line: 303
SubmitOrderedCompletionService$SubmitOrderFutureTask(FutureTask<V>).run() line:
138
ThreadPoolExecutor$Worker.runTask(Runnable) line: 886
ThreadPoolExecutor$Worker.run() line: 908
Thread.run() line: 619
Inspection of the JDK getNodeValueString shows that this error can only occur
if this function is called in parallel from two threads:
for (int i = chunkCount - 1; i >= 0; i--) {
fBufferStr.append((String)fStrChunks.elementAt(i));
}
value = fBufferStr.toString();
fStrChunks.removeAllElements();
One thread is looping over fStrChunks, while the other thread clear it via
removeAllElements.
> Multithreading bug: getBody sporadically returns null
> -----------------------------------------------------
>
> Key: CAMEL-2692
> URL: https://issues.apache.org/activemq/browse/CAMEL-2692
> Project: Apache Camel
> Issue Type: Bug
> Components: camel-core
> Affects Versions: 2.3.0
> Environment: Windows 7 64 bit, JDK 1.6.0_20
> Reporter: Roland Knight
> Assignee: Claus Ibsen
> Attachments: news_20100502000001.zip
>
>
> Note that the only workaround for this bug is to remove the
> parallelProcessing() call in the builder.
> I have a simple route that processes a file by splitting on a tag and
> processing the DOM of each split message. The problem is that getBody is
> randomly returning null but ONLY when using the parallelProcessing feature of
> split. For some runs of the same XML file, the error does not occur at all
> (the file is about 2MB of data), others it will happen once or twice. I am
> currently using the latest 2.3-SNAPSHOT.
> Also note, that after detecting the null, I tried calling
> getBody(String.class) - this also may return null. Sometimes it does return
> the proper XML.
> Route configuration that reproduces the problem (my input XML is about 2MB
> with about 500 article tags):
> public void configure() throws Exception {
> from("file:D:/inbox")
> .split(new XPathBuilder("//article"))
> .parallelProcessing() // remove this line
> getBody below never returns null
> .process(new Processor() {
> public void process(Exchange exchange) throws Exception {
> Message inMessage = exchange.getIn();
> org.w3c.dom.Document domDocument =
> inMessage.getBody(org.w3c.dom.Document.class);
> if (domDocument == null) {
> log("Null body");
> } else {
> // process DOM here
> }
> }
> })
> .end()
> }
> });
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