/** * try to grab a 'lock' on the task zk node to own and execute the task. * * <p> * * @param path zk node for the task */ private void grabTask(String path) { Stat stat = new Stat(); byte[] data; synchronized (grabTaskLock) { currentTask = path; workerInGrabTask = true; if (Thread.interrupted()) { return; } } try { try { if ((data = ZKUtil.getDataNoWatch(watcher, path, stat)) == null) { SplitLogCounters.tot_wkr_failed_to_grab_task_no_data.incrementAndGet(); return; } } catch (KeeperException e) { LOG.warn("Failed to get data for znode " + path, e); SplitLogCounters.tot_wkr_failed_to_grab_task_exception.incrementAndGet(); return; } SplitLogTask slt; try { slt = SplitLogTask.parseFrom(data); } catch (DeserializationException e) { LOG.warn("Failed parse data for znode " + path, e); SplitLogCounters.tot_wkr_failed_to_grab_task_exception.incrementAndGet(); return; } if (!slt.isUnassigned()) { SplitLogCounters.tot_wkr_failed_to_grab_task_owned.incrementAndGet(); return; } currentVersion = attemptToOwnTask( true, watcher, server.getServerName(), path, slt.getMode(), stat.getVersion()); if (currentVersion < 0) { SplitLogCounters.tot_wkr_failed_to_grab_task_lost_race.incrementAndGet(); return; } if (ZKSplitLog.isRescanNode(watcher, currentTask)) { ZkSplitLogWorkerCoordination.ZkSplitTaskDetails splitTaskDetails = new ZkSplitLogWorkerCoordination.ZkSplitTaskDetails(); splitTaskDetails.setTaskNode(currentTask); splitTaskDetails.setCurTaskZKVersion(new MutableInt(currentVersion)); endTask( new SplitLogTask.Done(server.getServerName(), slt.getMode()), SplitLogCounters.tot_wkr_task_acquired_rescan, splitTaskDetails); return; } LOG.info("worker " + server.getServerName() + " acquired task " + path); SplitLogCounters.tot_wkr_task_acquired.incrementAndGet(); getDataSetWatchAsync(); submitTask(path, slt.getMode(), currentVersion, reportPeriod); // after a successful submit, sleep a little bit to allow other RSs to grab the rest tasks try { int sleepTime = RandomUtils.nextInt(500) + 500; Thread.sleep(sleepTime); } catch (InterruptedException e) { LOG.warn("Interrupted while yielding for other region servers", e); Thread.currentThread().interrupt(); } } finally { synchronized (grabTaskLock) { workerInGrabTask = false; // clear the interrupt from stopTask() otherwise the next task will // suffer Thread.interrupted(); } } }