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Date: Tue, 07 Jan 2014 22:21:55 +0100
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To: Tomcat Users List <users@tomcat.apache.org>
Subject: Re: Packet misses in Tomcat
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Christopher,

Christopher Schultz wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA256
> 
> André,
> 
> On 1/7/14, 5:09 AM, André Warnier wrote:
>> I do not pretend to know your system, nor your application, nor
>> that the following is a definite explanation.  But on the base of
>> the currently available data, I would say : - it is quite unlikely
>> that Tomcat 7 is randomly "dropping requests". If it was, then I
>> would imagine that this list would be overflowing with cries for
>> help. There is quite a bit of traffic on this list related to
>> Tomcat 7, but I don't recall seeing any significant number of
>> issues mentioning "dropped requests". - it also doesn't seem, from
>> your wireshark-related observations, that the requests are being
>> lost outside of Tomcat. - so I would say at this point, that the
>> most likely place for requests to disappear is in your own
>> application.
> 
> It seems that Tomcat is not logging the request in its access log, so
> it's more likely that the request is either malformed to such an
> extent that Tomcat rejects the request altogether or that the request
> never reaches Tomcat.
> 
...
Hi. Of course I am going essentially by what the OP provided earlier as information, and 
he has not provided much details on the "disappearing" requests themselves, or on the 
channel through which these requests were reaching Tomcat.
But one thing that he did mention, is that these requests are similar - and even in 
general the same - as other requests which do get processed normally.
As per his own words :

"For the query regarding "All requests", all requests do not disappear. More importantly, 
sometimes all requests  reach the application when I POST same set of requests. To give a 
rough picture, 1-2 requests fail in a set of 45-50 requests and this behaviour varies [The 
request which failed in my one test cycle succeeds in another cycle]."

If we take this at face value, then it should not be so that these requests are so 
malformed that Tomcat discards them without further ado.
Also - but maybe I'm wrong there - I would expect, if Tomcat discards a request for being 
malformed - that something would appear in the Tomcat error log.  But according to the OP 
it doesn't.
Finally - and there is a bit of an assumption on my part here - I assume that when the OP 
says that he sees the request with Wireshark (prior to it "disappearing" in Tomcat), he 
was running Wireshark on the Tomcat host itself.  That would make it unlikely that another 
external component is at play.

All of the above led me to suspect that something in the application itself may be playing 
a role here.

Of course, that all does not necessarily prove that some other component than Tomcat is 
not dropping some packets/requests.

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