java - Creating multiple transactions in a single hibernate session -

i have created quartz job runs in background in jboss server , responsible updating statistical data @ regular interval (coupled database flags)

to load , persist using hibernate 4. works fine except 1 hick up.

the entire thread i.e. job wrapped in single transaction on period of time (as amount of data increases) becomes huge , worry some. trying break single large transaction multiple small ones, such each transaction process sub group of data.

problem: tried lamely wrap code loop , start/end transaction @ start/end of loop. expected didn't work. have been looking around various forums figure out solution have not come across indicates managing multiple transaction in single session (where in 1 transaction active @ time).

i relatively new hibernate , appreciate points me direction on achieving this.

update: adding code demonstrate trying achieve , mean when breaking multiple transaction. , stack trace when executed.

    log.info("starting calculation job.");      list<groupmodel> groups = collections.emptylist();     daofactory hibdaofactory = null;     try {         hibdaofactory = daofactory.hibernate();         hibdaofactory.begintransaction();         organizationdao groupdao = hibdaofactory.getgroupdao();         groups = groupdao.findall();         hibdaofactory.committransaction();     } catch (exception ex) {         hibdaofactory.rollbacktransaction();         log.error("error in transaction", ex);     }      try {         hibdaofactory = daofactory.hibernate();         statsdao statsdao = hibdaofactory.getstatsdao();         statsscaledvaluesdao statsscaleddao = hibdaofactory.getstatsscaledvaluesdao();          (groupmodel grp : groups) {             try {                 hibdaofactory.begintransaction();                 log.info("performing computation group " + grp.getname() + " ["                         + grp.getid() + "]");                  list<stats> statsdetail = statsdao.loadstatsgroup(grp.getid());                  // coputing steps here                  (entry origentry : statsentries) {                     entry.setcalculateditem1(origentry.getcalculateditem1());                     entry.setcalculateditem2(origentry.getcalculateditem2());                     entry.setcalculateditem3(origentry.getcalculateditem3());                      statsdetailsscaledvalues scvalues = entry.getscaledvalues();                     if (scvalues == null) {                         scvalues = new statsdetailsscaledvalues();                         scvalues.setid(origentry.getscrentryid());                         scvalues.setvalues(origentry.getscaledvalues());                     } else {                         scvalues.setvalues(origentry.getscaledvalues());                     }                     statsscaleddao.makepersistent(scvalues);                 }                  hibdaofactory.committransaction();             } catch (exception ex) {                 hibdaofactory.rollbacktransaction();                 log.error("error in transaction", ex);             } {              }         }     } catch (exception ex) {         log.error("error", ex);     } {      }      log.info("job complete."); 

following exception stacktrace getting upon execution of job

org.hibernate.sessionexception: session closed!     @ org.hibernate.internal.abstractsessionimpl.errorifclosed(abstractsessionimpl.java:127)     @ org.hibernate.internal.sessionimpl.createcriteria(sessionimpl.java:1555)     @ sun.reflect.generatedmethodaccessor469.invoke(unknown source)     @ sun.reflect.delegatingmethodaccessorimpl.invoke(unknown source)     @ java.lang.reflect.method.invoke(unknown source)     @ org.hibernate.context.internal.threadlocalsessioncontext$transactionprotectionwrapper.invoke(threadlocalsessioncontext.java:352)     @ $proxy308.createcriteria(unknown source)     @ com.blueoptima.cs.dao.impl.hibernate.generichibernatedao.findbycriteria(generichibernatedao.java:132)     @ com.blueoptima.cs.dao.impl.hibernate.scrstatsmanagementhibernatedao.loadstatsentriesfororg(scrstatsmanagementhibernatedao.java:22)     ... 3 more 

to understanding have read far hibernate, sessions , transactions. seems when session created attached thread , lives through out threads life or when commit or rollback called. thus, when first transaction committed session being closed , unavailable rest of threads life.

my question remains: how can have multiple transactions in single session?

more detail great , examples think should able have written here.

have 1 static sessionfactory (this big on memory) transactions want this.

someclass object = new someclass();  session session = sessionfactory().opensession() // create session object session.begintransaction(); //begins transaction session.save(object); // saves object remember isn't saved till session.commit() session.gettransaction().commit(); // persisting object session.close(); //closes transaction 

this how used transaction, not sure if many transaction have @ time. session object light weight compared sessionfactory in memory.

if want save more objects @ time in 1 transaction example.

someclass object1 = new someclass(); someclass object2 = new someclass(); someclass object2 = new someclass();  session.begintransaction(); session.save(object1); session.save(object2); session.save(object3); session.gettransaction().commit(); // when commit called save 3 objects session.close(); 

hope in way or points in right direction. think configure program condense transactions well. :)

edit here great youtube tutorial. guy broke down me.

hibernate tutorials