DFC Sessions - Interesting Findings.

Hello Experts,

I'm sure lot of you might have already answered thi question many a times but recently I've come across a interesting scenrio and hence need help.

I was working on a application using DFC at backend, Adobe Flex at front end technology and Spring as web app container. So obivious requirement was to manage Sessions, so we devloped one usersession class having a session manager, considering i injected superuser session thru spring.

Now, when a dctm suer logins, we create a instance of wrapper class and fill it with one session manager and from that session manager, i'll go all getSession, releaseSession. Now, the interesting part starts.

I've one scenrio where user can perform simultaneous operation (Threads). So i need to give new Session to every simultaneous operation else threads does not execute in parallel (Interesting ).

So i started calling newSession instead of getSession on SessionManager object. This Call occupies most of teh sessions and repository sessions limit is exhauted. Now in my application these operation happens every 5-10 secs so every 5-10 secs, I'll exhaust all sessions.

Need a solution experts.

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Comments

DCTM_Guru

How many threads are you spawning and are you releasing the sessions that you have created from newSession() method?

Anurag

I'm spawning 5-6 threads for every user and at max 40 users are working simultaneously.

Yes, all of my getsession/newSession are followed by releaseSession.

Also, I've max concurrent sessions defined at 300 to which my infra team syas its too high so cant extend beyond that.

lastnitescurry

Are you using one session manager for all users or a new session manager for each user.

it does sound very strange to have 4 or 5 sessions created when one is requested. I recently wrote an admin script that ran concurrently. Designed it from start to have unique sessions per thread... Would not be a good idea to share session across threads. I used one session manager and launched 10 sessions, one for each thread.

DCTM_Guru

So are you seeing max session exceeded when a couple of users are logged on or when you get closer to 40 max user? SessionManager has statistics method that you should be able to query to see if you are getting close to the 300 max sessions. You can also check when you are spawning 5-6 sessions (per user) to make sure that the previous user sessions have actually been closed (b/c if they havent been closed, then it 6+ sessions per user X 40 users will definitely exceed 300 max sessions).

aflowers001

How far apart are the get/release of sessions? If you're keeping them too long you'll quickly hit the max concurrent.

A good practice with this style of pooled connections is to only geta session when it is really needed, and then release it immediately after the work is was needed for is done.

This could entail passing round the sessionmanager as opposed the idfsession objects.

i.e.

main() {

init_session_manager()

call1(session_manager);

call2(session_manager);

}

call1(session_manager) {

do stuff

// now need to interact with dctm

get session

do query

get results

release session

// do more

// finally do more with dctm

get session

do update

release session

}

XdctmX

Did you try changing the history_cutoff and history_sessions keys in the server.ini?

Below are the default settings in the server.ini

concurrent_sessions = 100
client_session_timeout = 8

history_cutoff=240
history_sessions=100

Using the above setting will make sure that there will be only a maximum of 100 sessions at a time created by the server (concurrent_sessions = 100). If a session is not doing any process for 8 minutes then the session will be inactive (client_session_timeout = 8). These inactive/timed out sessions will be available for reuse for 240 minutes. Maximum number of history sessions are 100, so if history session exceeds 100 then the first inactivated session will be the first to be reclaimed by the by the server.