Interesting.  We're using the legacy low-level storage.  Is there a migration 
utility available for the switch to Akubra?

Our current next step is to try putting Apache httpd in front of Tomcat and see 
if its improved socket handling would help. 

Rob



-----Original Message-----
From: Stephen Bayliss [mailto:stephen.bayl...@acuityunlimited.net] 
Sent: Thursday, April 28, 2011 10:13 AM
To: 'Support and info exchange list for Fedora users.'
Subject: Re: [fcrepo-user] Http response 200 but no payload?

I just hit a similar (but unrelated) issue, the underlying cause of which
was a PrintWriter on the HTTP response not being flushed - I got partial
content, but it was intermittent.

So I wonder if this could be related?

Are you using the legacy low-level storage implementation or Akubra?

(And, if you have the opportunity to swap one for the other and see if the
problem persists then that may shed some more light.)

Steve



-----Original Message-----
From: Wolff, Robert [mailto:rob.wo...@unh.edu] 
Sent: 22 April 2011 18:58
To: Support and info exchange list for Fedora users.
Subject: Re: [fcrepo-user] Http response 200 but no payload?


I've tried the troubleshooting methods Aaron suggested.  

I should amend the problem to say that the server transmits some, but not
all, of the data for a requested datastream.  I've used a better packet
trace (Wireshark instead of Fiddler) to confirm this.

strace indicates the jvm is sending (sendto()) all of the data to the
socket.  There doesn't appear to be any blocked system calls, unless I'm
missing something.

jdb indicates that the thread(s) that get hung up are busy with
java.net.SocketOutputStream.socketWrite0.  I've attached the full stack
trace.  

Does this sound like a Fedora issue?  Are there relevant configuration
options we should check in Fedora, Tomcat, or the OS (RHEL5) that maybe we
hadn't considered? 

Thanks for any help. 

Rob 
 

-----Original Message-----
From: Aaron Birkland [mailto:birkl...@cs.cornell.edu] 
Sent: Wednesday, April 06, 2011 2:37 PM
To: Support and info exchange list for Fedora users.
Subject: Re: [fcrepo-user] Http response 200 but no payload?

Hi Rob,

> The problem is intermittent, unfortunately.  (Or, at least, I have not 
> been able to isolate the problem case.)

Next time it happens, you could try running strace -f against the java vm to
to see if there any blocking system calls that are stuck waiting (like
read() or socket()).  

If you have the freedom to do so at this point, you could also have the java
vm run in -Xdebug mode so that you can jump in, pause execution, and examine
the state of the java threads whenever you see this happening.

Between the two of these, I think you stand a fairly good chance of
narrowing down the basic problem area. 

By the way, what is the control group of these datastreams.  Are they all
Managed?

   -Aaron


>         
>         We're having an issue wherein Fedora/Tomcat will respond to a
>         REST API-A request with 200 and Transfer-Encoding: chunked but
>         then sends no chunks.  Here's a typical response header:
>         
>         HTTP/1.1 200 OK
>         Server: Apache-Coyote/1.1
>         Pragma: No-cache
>         Cache-Control: no-cache
>         Expires: Wed, 31 Dec 1969 19:00:00 EST
>         content-disposition: inline; filename="Annual report Town of
>         Center Harbor New Hampshire 2008.jpg"
>         Content-Type: image/jpeg
>         Transfer-Encoding: chunked
>         Date: Sun, 27 Mar 2011 01:46:23 GMT
>         
>         ...and that's it, no payload.




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