Gary, thanks for the reply.
Warm regards,
Jacky Wong
Software Engineer
Qinetics Solution Berhad
Gary Zhu wrote:
Jacky,
Whatever you quoted (in red) does not apply to
your case, because in most of your situations, you did not have
another Resin instance to be notified, as in "it will notify the owner of the change...." At
some point of step 2 and step 5, you did not even have any Resin
instance running.
But that does not mean this is not a problem.
JDBC based session store should always contain the last known valid
state, no matter which server was running. I noticed that your case
has been filed into Resin bug http://bugs.caucho.com/view.php?id=1544.
So, stop worrying.
Eric? Sam?
Warm regards,
Jacky Wong
Software Engineer
Qinetics Solution Berhad
Jacky wrote:
Dear all,
First of all, thanks for all the attentions. Greatly appreciated.
Josh,
- Please forgive me as i do not understand your "have your cake and eat
it too" metaphor :S
- I'm trying to implement the database backed distributed sessions as
shown in http://www.caucho.com/resin-3.0/config/sessions.xtp
and i dont take "turn it off" as a solution, at least not until i fully
understand that this will not work.
- You may be right with the clock of server A and server B not in sync,
I'll have it checked..
Eric,
- Yes, resin knows about my load balanced cluster (refer to the
specific settings below)
- I'm using apache with mod_caucho as the load balancer, is this inside
or outside? :D
- No, i'm not using <always-load-session>. I didnt' think that i
need (but i'll give it a shot). Referring to http://www.caucho.com/resin-3.0/config/sessions.xtp,
there is a paragraph stating this:
"For efficiency, the owning JVM keeps a cache of
the session value, so it only needs to query the database when the
session changes. If another JVM stores a new
session value, it will notify the owner of the change so the owner can
update its cache. Because of this notification, the database
store is cluster-aware."
my specific settings:
#Apache snippet
<VirtualHost *:80>
DocumentRoot /www/appA
ServerName somedomain.com
DirectoryIndex index.jsp
ResinConfigServer 192.168.1.1 6802
ResinConfigServer 192.168.1.2 6802
CauchoStatus yes
# do not remove, otherwise apache will serve the jsp source code once
resin is down
AddHandler caucho-request .jsp
</VirtualHost>
# Resin snippet
<!-- Yes i'm aware that client-live-time and read-timeout is not
supposed to be manually configured -->
<cluster>
<client-live-time>120s</client-live-time>
<srun id="a" host="192.168.1.1" port="6802" index="1"
read-timeout="120s"/>
<srun id="b" host="192.168.1.2" port="6802" index="2"
read-timeout="120s"/>
</cluster>
<persistent-store type="jdbc">
<init>
<data-source>jdbc/session</data-source>
</init>
</persistent-store>
<host id="somedomain.com" root-directory="/www/appA">
<web-app id="/" document-directory="/www/appA">
<session-config>
<!-- 3 hour timeout -->
<session-timeout>180</session-timeout>
<use-persistent-store/>
<always-save-session/>
</session-config>
<servlet-mapping url-pattern="/servlet/*"
servlet-name="invoker"/>
</web-app>
</host>
Sam,
I have 2 questions:
Quote:
At this point, A (the primary) will contact B to try to get any updates
to the session that have been made. Since B is down, A cannot get the
session from it.
- Since i use <always-save-session>, shouldn't it try to get from B, but couldn't it get from the DB?
Quote:
So it has to go with the outdated session that it
has, because it cannot get the updated session from B.
- Please do correct me if i'm wrong, referring to this:
"If another JVM stores a new session value, it will notify the owner of the change so
the owner can update its cache. Because of this notification, the database
store is cluster-aware."
- When B logs out my session, shouldn't it updates A's cache and the database at the same time?
- Is it because i didn't use <always-load-session> ??
Gary Zhu,
Quote:
Even if server A and server B are configured to use the same database on server C, for a particular user session (say session id: abcDGs299928), server A and server B will have two different database entries of the session data, am I getting it right ?
- I have thought of this as well when i look at the records in the table persistent_session of my mysql database.
- But still...
"If another JVM stores a new session value, it will notify the owner of the change so
the owner can update its cache. Because of this notification, the database
store is cluster-aware."
PS:
Apache/2.0.55
Resin professional 3.0.19.
Thanks all !!
Warm regards,
Jacky Wong
Software Engineer
Qinetics Solution Berhad
Sam wrote:
1. I start server A and login to my application
At this point, A will get your request and will become your primary
server, and B will be your secondary server.
2. I stop Server A and start Server B
3. I continue to work in the browser, my session stays intact and i
can proceed normally
At this point, you are using secondary server B. Your session updates
are saved on B.
4. I logout from my application and logout successfully cleared my
session variables (notice this from app log)
5. I stop Server B and start Server A
6. I try to type a password protected page in the browser and i *CAN
ACCESS* the protected page
At this point, A (the primary) will contact B to try to get any updates
to the session that have been made. Since B is down, A cannot get the
session from it. So it has to go with the outdated session that it
has, because it cannot get the updated session from B.
-- Sam
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