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 “captured context”, 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/tryResourceClose.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
