Thank you Mark, good points. In fact, I had configured memory limits with JAVA_OPTS variable. I haven't used JMeter yet because applications need javascript, X509 authentication and so forth. So at first glance, it seemed somewhat difficult to test it. But I'll give it a try again.
Thnx very much -----Mensaje original----- De: Mark Eggers [mailto:its_toas...@yahoo.com] Enviado el: lunes, 28 de abril de 2014 23:06 Para: Tomcat Users List Asunto: Re: Tomcat configuration with multiple webapps Comments inline: On 4/28/2014 1:38 PM, Baldur Dae wrote: > Hi guys, > > First of all, thank so much for your quick responses. I'm really > grateful ;) > > The scenario I've described is staging/QA, which has a single machine > running Apache httpd and another box running 2 Tomcat instances (it is > expected that production environment will have at least 2 boxes for > http and other 2 for Tomcats). > > Regarding hardware both machines have 3GB RAM and they only run some > batch scripts at midnight. Apache httpd box is doing great so far and > I haven't noticed load problems yet. > > I should provide a 99% availability although this requirement might be > flexible to some extent. As far as I know, concurrent user rate is > expected to be low i.e. magnitude order = 100. One advantage could be > that users are located within the same timezone. Thus there's a window > for new deployments. Unfortunately, there will be some occassions when > a war will have to be redeployed transparently to final users. > > All sessions are small since they store identity attributes. Besides, > all webapps are being migrated so that they use the same authorization > mechanism (Jasig CAS single sign on). Nevertheless, JSF applications > use ViewState which is ultimately stored in session. Luckily, web > services are stateless. > > With regard to versions, applications developed "in-house" use the > same versions (Spring 3, JSF 2, Hibernate 3) but this is not always > the standard stack due to some legacy apps. > > In order to face memory issues I've tweaked JAVA_OPTS to configure > memory limits. I tend to think that many problems come down to memory > leaks I would recommend that you set memory limits using CATALINA_OPTS (create a setenv.sh to set this). If you set JAVA_OPTS, then the shutdown task will also inherit your memory limits and could cause issues on memory-constrained systems. > produced by applications which must be fixed. Indeed Spring loads a > lot of classes but I guess this framework, as well as Hibernate or > JSF, are optimized enough, at least in this low-demanding scenario. > > So, bearing in mind your advice and other ideas I was thinking of my > current roadmap would comprise: > - Start out by a minimal set of wars and add every war gradually to > detect possible "big problems" > - Partition wars into 2 different groups: webapps and webservices > - Migrate the whole environment to Tomcat 7 > - Evaluate different connectors: BIO, NIO, APR > - Find better tools to monitor/profile applications to get a deeper > insight about what's going on > > Thanks very much for your valuable information > > Cheers Sounds like a good plan. One thing you might consider is to set up some JMeter systems to replay load scenarios from production (if possible). Unless your integration tests are pretty good, you might not catch some memory / performance / threading issues until you get into production. Stress testing with a good sample load and JMeter is one way of ferreting out these issues. > > > > > 2014-04-28 16:09 GMT+02:00 Neven Cvetkovic <neven.cvetko...@gmail.com>: > >> Hey Baldur, >> >> On Mon, Apr 28, 2014 at 8:00 AM, Baldur <baldur....@gmail.com> wrote: >> >>> Hi all, >>> >>> I'd like to get some help about my current architecture. >>> The >>> current scenario uses mod_jk to connect Apache httpd and Tomcat6. I >>> have two Tomcat instances (using DeltaManager for session >>> replication and sticky session enabled) in order to provide high >>> availability and balance load across instances. Currently Tomcat >>> manages 28 webapps and 7 of them are only web services. Generally >>> speaking, a webapp usually involves JSF or Struts while a web >>> services war involves JAX-WS. Both types of >> application >>> have a common stack implemented with Spring and Hibernate. As a >>> result, each application produces a war of around 40-50 MB. >>> >>> >> Here are some questions that can make us better understand your >> environment and further the discussion on your choices: >> >> 1. What kind of hardware do you run these two instances on (single >> box, 2 boxes, how much RAM, etc..)? Do you have resources to run more >> Tomcat instances on this(these) box(es)? >> >> 2. Do you have HA as requirement for all the apps? Do you have any >> specific SLAs (service level agreements) you need to maintain? >> >> 3. Can you live without session replication, and just live with the >> sticky sessions? What kind of data do you keep in your sessions? How >> big are these sessions? >> >> 4. What's the order of magnitude for your concurrent users (100s, >> 1000s, >> 10000s) for these applications? I.e how many concurrent sessions do >> you need to maintain? >> >> 5. Are your webservices stateless, most of them usually are? >> >> 6. Do these applications share any libraries (Hibernate, Struts2, >> Spring, etc...)? What is the upgrade/release cycle for these >> applications? How do you deal with differences in versioning, e.g. >> Hibernate3 vs Hibernate4, or Spring 3.0 vs Spring 3.2 vs Spring 4.0, etc... >> >> In the ideal world, with infinite amount of resources (hardware, >> staff, >> etc) - I would have one Tomcat instance (or one cluster) per >> application, so I can segregate and isolate my application >> environments (JVMs). However, given huge number of applications, and >> that we don't have that much money to spare - that segregation might >> be too extreme, too wasteful - so we typically organize our >> applications to co-exist on the Tomcat instance(s), based on their >> importance, SLA agreements, release lifecycle, business operations, etc. >> >> >> >>> I'd like to ask you several questions to provide >>> better >>> performance: >>> >>> * Which approach would be appropriate for this scenario? All wars >>> in >>> one cluster? Maybe move web services to other cluster? >>> >>> >> It might be useful to move webservices to a separate cluster that >> might not need session replication. You might gain some performance >> benefit by not having to replicate sessions across cluster members. >> Though, having 28 webapps (wars) on the same instance (clustered >> instance), my concern is isolation. What happens if one application >> trashes one of your JVMs? Then all other 27 apps are going to suffer >> and stress your other JVM. If you truly need HA, consider moving >> these apps on their own environment, independent of other apps. >> >> >> >>> * In order to improve deployments, which technique can I use to >>> minimize war size? Will be the cause of memory issues? I have tried >>> to >> put >>> some common jars (spring, apache-commons and so on) in Tomcat lib >>> but I don't know if there is a better approach by other means. >>> >>> >> Have you observed any issues with the sizing of the apps, e.g. >> OutOfMemoryError (permgen space)? Ultimately, if you deploy ton of >> applications, and they all have ton of third-party libraries (think >> Spring, Hibernate, etc.) - you will end up with larger PermGen >> consumption, which might be exhausted after N applications. >> >> Placing shared libraries in the Tomcat shared folder might help with >> memory sizing issues, but then you face the upgrade lifecycle issue. >> You will need to coordinate the application upgrade properly. Also, >> you might end up with weird errors - because frameworks might share >> some objects statically, and that's not what your intent was, etc. >> Thus, using shared libraries need to be carefully planned. Usually, >> benefits of shared libraries are not worth the trouble, so we end up >> packaging each application separately. Shared libraries can be very >> useful when admins want to enforce library versioning, and force >> developers to use given environment, rather than them including what >> they want/need. It's an architectural decision, not so much performance >> optimization decision. >> >> >> >>> I read as much as I can but I'm stuck trying to find the best tools >>> to monitor the system and tackle memory issues (such as the dreaded >> PermGen). >>> I think it's a quite common scenario for a relatively small >>> production environment but I don't find the best configuration that >>> suits this type >> of >>> deployment. >>> >>> >> Well, you probably want to profile your application(s) and see how >> they perform under various configuration options (memory sizing, >> connector sizing, etc). That gets much easier when you have all apps >> segmented to different environments. Your HTTPD setup helps a lot, as >> your clients don't care where HTTPD sends the traffic in the backend, >> to two instances or to twenty-eight instances. There might be minimal >> or insignificant performance overhead in maintaining 2 or 28 backend Tomcat >> instances connections. >> However, I would probably want to measure that too and see how it >> behaves under real-life like traffic. >> >> >>> Any help would be much appreciated. >>> >>> Thanks very much in advance >>> >>> >> Hope these questions give you something to think about and revisit >> and justify your choices. >> >> Cheers! >> Neven >> > . . . . just my two cents /mde/ --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
