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From Amit Rawat <Amit.Ra...@guavus.com>
Subject Re: Tomcat simple tcp cluster doesn't work on switching browser
Date Mon, 23 Nov 2015 05:47:03 GMT
Hi,

I tried to see if the connection between two tomcats is working correctly
& took a netstat with the receiver port(4010) of tomcat 2 & process
id(13437) of tomcat 1 which gives the following.
netstat -anp | grep 4010 | grep 192.168.x.x:4010 | grep 13437/java
tcp        0    580 ::ffff:192.168.x.x:41140 ::ffff:192.168.x.x:4010
ESTABLISHED 13437/java
tcp        0    578 ::ffff:192.168.x.x:41136 ::ffff:192.168.x.x:4010
ESTABLISHED 13437/java


netstat -anp | grep 4010 | grep 192.168.x.x:4010 | grep 13437/java
tcp        0    580 ::ffff:192.168.x.x:41146 ::ffff:192.168.x.x:4010
ESTABLISHED 13437/java
tcp        0    826 ::ffff:192.168.x.x:41151 ::ffff:192.168.x.x:4010
ESTABLISHED 13437/java


netstat -anp | grep 4010 | grep 192.168.x.x:4010 | grep 13437/java
tcp        0    757 ::ffff:192.168.x.x:41223 ::ffff:192.168.x.x:4010
ESTABLISHED 13437/java


netstat -anp | grep 4010 | grep 192.168.x.x:4010 | grep 13437/java
tcp        0    580 ::ffff:192.168.x.x:41292 ::ffff:192.168.x.x:4010
ESTABLISHED 13437/java
tcp        0    757 ::ffff:192.168.x.x:41286 ::ffff:192.168.x.x:4010
ESTABLISHED 13437/java
tcp        0    578 ::ffff:192.168.x.x:41282 ::ffff:192.168.x.x:4010
ESTABLISHED 13437/java
tcp        0      1 ::ffff:192.168.x.x:41293 ::ffff:192.168.x.x:4010
SYN_SENT    13437/java


netstat -anp | grep 4010 | grep 192.168.x.x:4010 | grep 13437/java


I have two observations :
a) The no of connections keeps changing form 0 to 4 .
b) When this issue occurs , the Receive queue starts filling up

Is observation 'a' normal behaviour? And are there ways to identify why
the receive queue filling up ?





On 17/11/15 3:06 pm, "Amit Rawat" <Amit.Rawat@guavus.com> wrote:

>Hi Chris,
>
>It might seem that both are going to SERVER-1 because I have set the
>jvmRoute for both instances of tomcat is set to SERVER-1. I had started
>with setting different jvmRoute for both and I faced the same issue . Then
>I tried setting them the same since I thought jvmRoute should be unique to
>the server therefore I used server name . Although now I think they should
>be unique to the tomcat instance.
>
>I am not using a load balancer. The two tomcats expose different services
>& I need to share sessions between those services for a logged in user.
>The scenario is that I login through tomcat 1, query it a few times, then
>query tomcat 2 using the same session-id .
>
>My apologies if it seemed rude , but I pasted the link to my questions on
>SO as I didn¹t want the mail to be too long & unreadable . Also, the post
>on SO , has links to other SO suggestions that I have already tried.
>Again, my apologies, it was not my intention to be either lazy or rude.
>
>
>Thanks for the reply,
>Amit
>
>On 17/11/15 3:28 am, "Christopher Schultz" <chris@christopherschultz.net>
>wrote:
>
>>Amit,
>>
>>On 11/16/15 7:21 AM, Amit Rawat wrote:
>>> Thanks for the reply. I understand that on changing browsers, a new
>>> session would need to be established & that is indeed what I do . On
>>> changing browsers , I login again , creating a new session .
>>> As can be seen in the logs I pasted on stack overflow : New Session :::
>>> 6003A09956987A2035EB9BB1C5D7C157.SERVER-1 . But as you can see from the
>>> logs , the sessions created or destroyed are not shared with the other
>>> tomcat by the tomcat to which I send my requests .
>>
>>It's not clear which Tomcat is receiving which requests... they all look
>>like they are going to SERVER-1. Are you sure your lb is working as
>>expected?
>>
>>While some of us lurk on SO, posting to this list and asking people to
>>go to SO to answer your question is a little lazy (or perhaps rude). IF
>>you want real advice, come here and give us all the information we need
>>to help you. Then stick around and become part of the community. If you
>>just want random advice from people on the internet, stick with SO.
>>
>>-chris
>>
>>> On 16/11/15 5:30 pm, "André Warnier (tomcat)" <aw@ice-sa.com> wrote:
>>> 
>>>> On 16.11.2015 11:36, Amit Rawat wrote:
>>>>> Hi,
>>>>>
>>>>>
>>>>>
>>>>> I'm observing some strange behaviour between two instances of
>>>>> apache-tomcat-7.0.41 running on the same server. Sessions are shared
>>>>> between the servers on multiple logins/logouts on the same browser ,
>>>>>but
>>>>> when i switch browsers , the session sharing stops .
>>>>>
>>>>> I have posted a question on stack overflow where you can find more
>>>>> details on what I have tried & my observations :
>>>>>
>>>>>
>>>>> 
>>>>>http://stackoverflow.com/questions/33546555/tomcat-simple-tcp-cluster-
>>>>>d
>>>>>oe
>>>>> snt-work-on-switching-browser
>>>>>
>>>>>   Any help would be appreciated.
>>>>>
>>>>
>>>> Off the top of my head, I would say
>>>> - a "session" saved on the server, is identified by a "session-id"
>>>>(some
>>>> kind of large 
>>>> alphanumeric string, unique)
>>>> - to allow a browser to re-connect to the same session during several
>>>> interactions, this
>>>> session-id is initially sent to the browser, contained in a cookie
>>>> - whenever the browser interacts with the same server/cluster, it
>>>>resends
>>>> this cookie, and
>>>> this is what allows the server to re-connect this browser to the saved
>>>> session
>>>>
>>>> - of course, if you switch browsers, the new browser does not have
>>>>that
>>>> cookie. So it does
>>>> not send it to the server/cluster, and it gets a new session, with a
>>>> different session-id.
>>>>
>>>> Or did I misunderstand your explanation of what happens ?
>>>>
>>>>
>>>>
>>>>
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