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From "Ian Blavins (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HTTPCORE-195) Make it possible to tolerate truncated chunk streams
Date Sat, 22 Sep 2012 23:15:07 GMT

    [ https://issues.apache.org/jira/browse/HTTPCORE-195?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13461288#comment-13461288
] 

Ian Blavins commented on HTTPCORE-195:
--------------------------------------

G'day

I was experiencing the same problem as the originator of this issue (but since I was running
later code I was actually getting the new TruncatedChunkException that was added to the code
as a result of this issue).

It turned out I was experiencing the problem because I was closing the connection to the web
server while I was still reading the chunk. I suspect that is why the originator was having
his problems. I suggest the reason "... we only crawled 20 websites before we started running
into this problem. " was that the first 19 didn't use chunked output and the reason "We are
frequently encountering this issue" was that there are plenty of sites that do chunk. 

Note that it would be possible to process a chunked site without error if the relative timing
of the connection close and completion of the chunk read(s) was favourable. So the fact that
some chunked sites were processed without error wouldn't necessarily disprove the suggestion.
I would expect that some chunked sites would reliably give the problem and some would give
it some of the time.

That being said I didn't find the TruncatedChunkException to be much help because I was working
at the HttpResponse and HttpClient level. By the time the exception reached that level it
was way too late to do anything useful about it. For the exception to be useful at that level
it would need a parameter in CoreConnectionPNames. This would be used by callers of ChunkedInputStream
to decide whether to treat TruncatedChunkException as fatal or treat it as end of file. There
is already a parameter that deals with buffering of small chunks so users of ChunkedInputStream
would appear to have access to the parameters.

                
> Make it possible to tolerate truncated chunk streams
> ----------------------------------------------------
>
>                 Key: HTTPCORE-195
>                 URL: https://issues.apache.org/jira/browse/HTTPCORE-195
>             Project: HttpComponents HttpCore
>          Issue Type: Improvement
>          Components: HttpCore NIO
>    Affects Versions: 4.0
>            Reporter: Patrick Moore
>            Priority: Minor
>             Fix For: 4.1-alpha1
>
>         Attachments: chunkValidationDecoupling.patch, HTTPCORE-195.patch
>
>
> Our server is webcrawling.
> We are frequently encountering this issue. We think this might be related to something
on the server that we are scanning. But that doesn't matter. We need to handle such cases
without exceptions. (From my perspective, such things should generate a debug message -- certainly
not an exception that ends processing and throws away the retrieved content! )
> http://stuftpizza.com/ seems to reliably result in this problem
> May be TransferEncoding? http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.6
> Either way we need to be able to deal with issues on the other servers.
> {{{
> Date	Mon, 20 Apr 2009 03:56:45 GMT
> Server	Apache/2.2.3 (Red Hat)
> Accept-Ranges	bytes
> Connection	close
> Transfer-Encoding	chunked
> Content-Type	text/html
> '''Request Headers'''
> Host	stuftpizza.com
> User-Agent	Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.0.8) Gecko/2009032608
Firefox/3.0.8
> Accept	text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
> Accept-Language	en-us,en;q=0.5
> Accept-Encoding	gzip,deflate
> Accept-Charset	ISO-8859-1,utf-8;q=0.7,*;q=0.7
> Keep-Alive	300
> Connection	keep-alive
> Cookie	
> __utma=47358053.1237981682.1240199754.1240199754.1240199754.1; __utmb=47358053; __utmc=47358053;
__utmz
> =47358053.1240199754.1.1.utmccn=(direct)|utmcsr=(direct)|utmcmd=(none)
> Cache-Control	max-age=0
> }}}
> {{{
> 20:51:08,768 INFO  [nioEventListener] Request http://stuftpizza.com/ failed with exception.
> org.apache.http.MalformedChunkCodingException: Truncated chunk
> 	at org.apache.http.impl.nio.codecs.ChunkDecoder.read(ChunkDecoder.java:203)
> 	at org.apache.http.nio.util.SimpleInputBuffer.consumeContent(SimpleInputBuffer.java:60)
> 	at org.apache.http.nio.entity.BufferingNHttpEntity.consumeContent(BufferingNHttpEntity.java:72)
> 	at org.apache.http.nio.protocol.AsyncNHttpClientHandler.inputReady(AsyncNHttpClientHandler.java:236)
> 	at org.apache.http.nio.protocol.BufferingHttpClientHandler.inputReady(BufferingHttpClientHandler.java:118)
> 	at org.apache.http.impl.nio.DefaultNHttpClientConnection.consumeInput(DefaultNHttpClientConnection.java:178)
> 	at org.apache.http.impl.nio.DefaultClientIOEventDispatch.inputReady(DefaultClientIOEventDispatch.java:146)
> 	at com.amplafi.iomanagement.http.UniversalIOEventDispatch.inputReady(UniversalIOEventDispatch.java:133)
> 	at $IOEventDispatch_120c19cd1c7.inputReady($IOEventDispatch_120c19cd1c7.java)
> 	at org.apache.http.impl.nio.reactor.BaseIOReactor.readable(BaseIOReactor.java:153)
> 	at org.apache.http.impl.nio.reactor.AbstractIOReactor.processEvent(AbstractIOReactor.java:314)
> 	at org.apache.http.impl.nio.reactor.AbstractIOReactor.processEvents(AbstractIOReactor.java:294)
> 	at org.apache.http.impl.nio.reactor.AbstractIOReactor.execute(AbstractIOReactor.java:256)
> 	at org.apache.http.impl.nio.reactor.BaseIOReactor.execute(BaseIOReactor.java:96)
> 	at org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor$Worker.run(AbstractMultiworkerIOReactor.java:556)
> 	at java.lang.Thread.run(Thread.java:637)
> }}}

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