On 12/30/06, Peter Coppens <[EMAIL PROTECTED]> wrote:
Actually it just seems to be related to the fact that under heavy load the db connection starts to take longer than the timeout.
Thats a lot. What is your timeout configured to?
Apparently, a call to request.getSession() somewhere in the middel of the doGet processing will also trigger invalidating the session, which is kind of a nuisance as one should then apparently constantly check whether the session has not expired during request processing. I assume this is Servlet spec compliant, but it does seem to make my life rather complex. Would there be anyone having any suggestions to deal with this.
We might need some more details on your application to give you meaningful suggestions, but just from the hip I'd say following: 1. You make DB requests not only from tomcat which is suboptimal anyway, but also directly from the servlet, which would mean that you utterly need to refactor your application anyway. 2. Apparently your timeouts are way to low. On the other hand, it can't be healthy if your requests last longer than hours (default timeout for the session are 2 hours) 3. In case you can't change anything other, you could consider starting a thread on the start of the request which just calls session.get/put with dummy attributes periodically to prevent the session from being timeouted. However this feature has to be implemented carefully, since it can cause much harm with regard to garbage collection if your thread instances sticks and keep references to the session or similar. By the way, what do you mean by "heavy load"? Regards Leon
Thanks, Peter Leon Rosenberg-3 wrote: > > On 12/30/06, Peter Coppens <[EMAIL PROTECTED]> wrote: >> >> I am gathering more evidence that this is related to a session expiring >> on >> one hand and a request being processed for that same session. >> >> I have been debugging the tomcat code a bit, and I have the *impression* >> that the expiration handling is not thread safe. It seems possible at >> first >> sight that the background processor decides a session is expired while at >> the same time another thread starts a request for that same session. >> >> I will try to debug a bit more and if I find more I will let you know. > > The question is whether the next request get the "right" session again > or not. I had the impression from your first post, that this is the > case: > Request A - Session 1 > Request B - Session 2 <-- which is wrong > Request C - Session 1 again. > > I observed this behaviour 3 years ago on a resin 2.1.x, but had not > enough time to debug it. > > regards > Leon >> >> Thanks, >> >> Peter >> >> PS What does "O/T" mean ? > > Off Topic > >> >> >> Martin Gainty wrote: >> > >> > Agreed >> > Once you have your use cases and test cases identified >> > >> > If you want the server to maintain its own side of the relationship >> > independent of client activity then you should consider container >> managed >> > persistence >> > More info avaialable at >> > >> http://www.javaworld.com/javaworld/jw-08-2006/jw-0828-persistence.html?page=6 >> > >> > Feel free to contact me offline as this is definitely O/T >> > Martin-- >> > >> --------------------------------------------------------------------------- >> > This e-mail message (including attachments, if any) is intended for the >> > use of the individual or entity to which it is addressed and may >> contain >> > information that is privileged, proprietary , confidential and exempt >> from >> > disclosure. If you are not the intended recipient, you are notified >> that >> > any dissemination, distribution or copying of this communication is >> > strictly prohibited. >> > >> --------------------------------------------------------------------------- >> > Le présent message électronique (y compris les pièces qui y sont >> annexées, >> > le cas échéant) s'adresse au destinataire indiqué et peut contenir des >> > renseignements de caractère privé ou confidentiel. Si vous n'êtes pas >> le >> > destinataire de ce document, nous vous signalons qu'il est strictement >> > interdit de le diffuser, de le distribuer ou de le reproduire. >> > ----- Original Message ----- >> > From: "Leon Rosenberg" <[EMAIL PROTECTED]> >> > To: "Tomcat Users List" <users@tomcat.apache.org> >> > Sent: Friday, December 29, 2006 6:31 AM >> > Subject: Re: session#getId changes during doGet invocation under heavy >> > load >> > >> > >> >> Do I understand it right, that you made it a reproduceable testcase? >> >> If so, can we have a look on it? >> >> >> >> thank you >> >> Leon >> >> >> >> On 12/29/06, Peter Coppens <[EMAIL PROTECTED]> wrote: >> >>> >> >>> Thanks Chuck. >> >>> >> >>> I have done some further research and I have the impression that >> there >> >>> is >> >>> some kind of race condition where a session that is being removed >> >>> because of >> >>> a timeout is also handling requests. >> >>> >> >>> The loggings indicate that a session is destroyed but then >> nevertheless >> >>> a >> >>> doGet is invoked with a request parameter that refers to that timed >> out >> >>> session. >> >>> >> >>> If I crank up the timeout, seriously reducing the chances a session >> >>> times >> >>> out before it has completed all the client requests it is supposed to >> >>> handle >> >>> during the test, the problem does no longer occur. >> >>> >> >>> I am not sure where that leaves me. I am still uncertain as to what >> the >> >>> servlet is doing wrong. >> >>> >> >>> Would you (or anyone else) have any other comments on this? >> >>> >> >>> Thanks, >> >>> >> >>> Peter >> >>> >> >>> >> >>> >> >>> Caldarale, Charles R wrote: >> >>> > >> >>> >> From: Peter Coppens [mailto:[EMAIL PROTECTED] >> >>> >> Subject: session#getId changes during doGet invocation under >> >>> >> heavy load >> >>> >> >> >>> >> THe problem I run into is that, under heavy load, during the >> >>> >> doGet invocation for the login request the session attached >> >>> >> to the request is changed by some other thread (the value >> >>> >> returned from getId changes and attributes that are originally >> >>> >> set are removed). >> >>> > >> >>> > This is most likely an application problem - storing session- or >> >>> > request-specific data in an inappropriately scoped structure (e.g., >> a >> >>> > servlet field). Under light load, this won't hurt, since the >> >>> insertion >> >>> > and retrieval for a given request don't overlap any other requests. >> >>> As >> >>> > the load increases, so does the probability of an overlap and >> >>> erroneous >> >>> > retrieval of data for another request. >> >>> > >> >>> > - Chuck >> >>> > >> >>> > >> >>> > THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE >> >>> PROPRIETARY >> >>> > MATERIAL and is thus for use only by the intended recipient. If you >> >>> > received this in error, please contact the sender and delete the >> >>> e-mail >> >>> > and its attachments from all computers. >> >>> > >> >>> > >> --------------------------------------------------------------------- >> >>> > To start a new topic, e-mail: users@tomcat.apache.org >> >>> > To unsubscribe, e-mail: [EMAIL PROTECTED] >> >>> > For additional commands, e-mail: [EMAIL PROTECTED] >> >>> > >> >>> > >> >>> > >> >>> >> >>> -- >> >>> View this message in context: >> >>> >> http://www.nabble.com/session-getId-changes-during-doGet-invocation-under-heavy-load-tf2892448.html#a8085181 >> >>> Sent from the Tomcat - User mailing list archive at Nabble.com. >> >>> >> >>> >> >>> --------------------------------------------------------------------- >> >>> To start a new topic, e-mail: users@tomcat.apache.org >> >>> To unsubscribe, e-mail: [EMAIL PROTECTED] >> >>> For additional commands, e-mail: [EMAIL PROTECTED] >> >>> >> >>> >> >> >> >> --------------------------------------------------------------------- >> >> To start a new topic, e-mail: users@tomcat.apache.org >> >> To unsubscribe, e-mail: [EMAIL PROTECTED] >> >> For additional commands, e-mail: [EMAIL PROTECTED] >> >> >> >> >> > >> >> -- >> View this message in context: >> http://www.nabble.com/session-getId-changes-during-doGet-invocation-under-heavy-load-tf2892448.html#a8097754 >> Sent from the Tomcat - User mailing list archive at Nabble.com. >> >> >> --------------------------------------------------------------------- >> To start a new topic, e-mail: users@tomcat.apache.org >> To unsubscribe, e-mail: [EMAIL PROTECTED] >> For additional commands, e-mail: [EMAIL PROTECTED] >> >> > > --------------------------------------------------------------------- > To start a new topic, e-mail: users@tomcat.apache.org > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > > -- View this message in context: http://www.nabble.com/session-getId-changes-during-doGet-invocation-under-heavy-load-tf2892448.html#a8099384 Sent from the Tomcat - User mailing list archive at Nabble.com. --------------------------------------------------------------------- To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
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