Yes, there was another discussion here: http://markmail.org/thread/uf6bxab6u4z4fmrp
On 1/6/14 3:18 PM, "Kelven Yang" <kelven.y...@citrix.com> wrote: >Java 7 has been around for some time now. I strongly suggest CloudStack >to adopt Java 7 as early as possible, the reason I feel like to raise the >issue is from the some of practicing with the new DB transaction pattern, >as following example shows. The new Transaction pattern uses anonymous >class to beautify the code structure, but in the mean time, it will >introduce a couple runtime costs > > 1. Anonymous class introduces a ³captured context², information >exchange between the containing context and the anonymous class >implementation context has either to go through with mutable passed-in >parameter or returned result object, in the following example, without >changing basic Transaction framework, I have to exchange through returned >result with an un-typed array. This has a few implications at run time, >basically with each call of the method, it will generate two objects to >the heap. Depends on how frequently the involved method will be called, >it may introduce quite a burden to java GC process > 2. Anonymous class captured context also means that there will be more >hidden classes be generated, since each appearance of the anonymous class >implementation will have a distance copy of its own as hidden class, it >will generally increase our permanent heap usage, which is already pretty >huge with current CloudStack code base. > >Java 7 has a language level support to address the issues in a cheaper >way that our current DB Transaction code pattern is trying to solve. >http://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClo >se.html. So, time to adopt Java 7? > > public Outcome<VirtualMachine> startVmThroughJobQueue(final String >vmUuid, > final Map<VirtualMachineProfile.Param, Object> params, > final DeploymentPlan planToDeploy) { > > final CallContext context = CallContext.current(); > final User callingUser = context.getCallingUser(); > final Account callingAccount = context.getCallingAccount(); > > final VMInstanceVO vm = _vmDao.findByUuid(vmUuid); > > > Object[] result = Transaction.execute(new >TransactionCallback<Object[]>() { > @Override > public Object[] doInTransaction(TransactionStatus status) { > VmWorkJobVO workJob = null; > > _vmDao.lockRow(vm.getId(), true); > List<VmWorkJobVO> pendingWorkJobs = >_workJobDao.listPendingWorkJobs(VirtualMachine.Type.Instance, > vm.getId(), VmWorkStart.class.getName()); > > if (pendingWorkJobs.size() > 0) { > assert (pendingWorkJobs.size() == 1); > workJob = pendingWorkJobs.get(0); > } else { > workJob = new VmWorkJobVO(context.getContextId()); > > >workJob.setDispatcher(VmWorkConstants.VM_WORK_JOB_DISPATCHER); > workJob.setCmd(VmWorkStart.class.getName()); > > workJob.setAccountId(callingAccount.getId()); > workJob.setUserId(callingUser.getId()); > workJob.setStep(VmWorkJobVO.Step.Starting); > workJob.setVmType(vm.getType()); > workJob.setVmInstanceId(vm.getId()); > >workJob.setRelated(AsyncJobExecutionContext.getOriginJobContextId()); > > // save work context info (there are some duplications) > VmWorkStart workInfo = new >VmWorkStart(callingUser.getId(), callingAccount.getId(), vm.getId(), >VirtualMachineManagerImpl.VM_WORK_JOB_HANDLER); > workInfo.setPlan(planToDeploy); > workInfo.setParams(params); > workJob.setCmdInfo(VmWorkSerializer.serialize(workInfo)); > > _jobMgr.submitAsyncJob(workJob, >VmWorkConstants.VM_WORK_QUEUE, vm.getId()); > } > > return new Object[] {workJob, new Long(workJob.getId())}; > } > }); > > final long jobId = (Long)result[1]; > AsyncJobExecutionContext.getCurrentExecutionContext().joinJob(jobId); > > return new VmStateSyncOutcome((VmWorkJobVO)result[0], > VirtualMachine.PowerState.PowerOn, vm.getId(), null); > } > > >Kelven
