部署Hive后启动HiveServer2居然抛出了以下的异常：
反复检查了配置文件，配置都是正确，就是启动失败，实在没有办法只能根据错误信息排查。
* 找到HiveConf.java-->unitFor(String unit, TimeUnit defaultUnit)方法，通过代码可以看出是因为unit这个变量都是false才抛出的异常，那么就继续看是哪里调用了这个方法。
1 public static TimeUnit unitFor(String unit, TimeUnit defaultUnit) {
2 unit = unit.trim().toLowerCase();
3 if (unit.isEmpty()) {
4 if (defaultUnit == null) {
5 throw new IllegalArgumentException("Time unit is not specified");
6 }
7 return defaultUnit;
8 } else if (unit.equals("d") || unit.startsWith("day")) {
9 return TimeUnit.DAYS;
10 } else if (unit.equals("h") || unit.startsWith("hour")) {
11 return TimeUnit.HOURS;
12 } else if (unit.equals("m") || unit.startsWith("min")) {
13 return TimeUnit.MINUTES;
14 } else if (unit.equals("s") || unit.startsWith("sec")) {
15 return TimeUnit.SECONDS;
16 } else if (unit.equals("ms") || unit.startsWith("msec")) {
17 return TimeUnit.MILLISECONDS;
18 } else if (unit.equals("us") || unit.startsWith("usec")) {
19 return TimeUnit.MICROSECONDS;
20 } else if (unit.equals("ns") || unit.startsWith("nsec")) {
21 return TimeUnit.NANOSECONDS;
22 }
23 throw new IllegalArgumentException("Invalid time unit " + unit);
24 }
* 通过错信息知道是HiveConf.java-->toTime(String value, TimeUnit inputUnit, TimeUnit outUnit)方法调用了unitFor方法，并且传递处理后的value值，继续看代码。
1 public static long toTime(String value, TimeUnit inputUnit, TimeUnit outUnit) {
2 String[] parsed = parseTime(value.trim());
3 return outUnit.convert(Long.valueOf(parsed[0].trim().trim()), unitFor(parsed[1].trim(), inputUnit));
4 }
* 通过错信息知道是HiveConf.java-->getTimeVar(Configuration conf, ConfVars var, TimeUnit outUnit)方法调用了toTiime方法，并且通过getVar(conf, var)方法传递处理后的var值，继续看代码。
1 public static long getTimeVar(Configuration conf, ConfVars var, TimeUnit outUnit) {
2 return toTime(getVar(conf, var), getDefaultTimeUnit(var), outUnit);
3 }
* getTimeVar方法被CLIServer.java-->getOperationStatus方法调用了，继续看代码。
1 public OperationStatus getOperationStatus(OperationHandle opHandle)
2 throws HiveSQLException {
3 Operation operation = sessionManager.getOperationManager().getOperation(opHandle);
4 /**
5 * If this is a background operation run asynchronously,
6 * we block for a configured duration, before we return
7 * (duration: HIVE_SERVER2_LONG_POLLING_TIMEOUT).
8 * However, if the background operation is complete, we return immediately.
9 */
10 if (operation.shouldRunAsync()) {
11 HiveConf conf = operation.getParentSession().getHiveConf();
12 long timeout = HiveConf.getTimeVar(conf,
13 HiveConf.ConfVars.HIVE_SERVER2_LONG_POLLING_TIMEOUT, TimeUnit.MILLISECONDS);
14 try {
15 operation.getBackgroundHandle().get(timeout, TimeUnit.MILLISECONDS);
16 } catch (TimeoutException e) {
17 // No Op, return to the caller since long polling timeout has expired
18 LOG.trace(opHandle + ": Long polling timed out");
19 } catch (CancellationException e) {
20 // The background operation thread was cancelled
21 LOG.trace(opHandle + ": The background operation was cancelled", e);
22 } catch (ExecutionException e) {
23 // The background operation thread was aborted
24 LOG.warn(opHandle + ": The background operation was aborted", e);
25 } catch (InterruptedException e) {
26 // No op, this thread was interrupted
27 // In this case, the call might return sooner than long polling timeout
28 }
29 }
30 OperationStatus opStatus = operation.getStatus();
31 LOG.debug(opHandle + ": getOperationStatus()");
32 sessionManager.clearIpAddress();
33 return opStatus;
34 }
* 在上面的方法有以下这句代码。
1 long timeout = HiveConf.getTimeVar(conf, HiveConf.ConfVars.HIVE_SERVER2_LONG_POLLING_TIMEOUT, TimeUnit.MILLISECONDS);
* 可以看到是把HiveConf.ConfVars.HIVE_SERVER2_LONG_POLLING_TIMEOUT这个参数的值传递到getTimeVar方法的，现在看看这个参数。
1 HIVE_SERVER2_LONG_POLLING_TIMEOUT("hive.server2.long.polling.timeout", "5000ms", new TimeValidator(TimeUnit.MILLISECONDS))
* 对应配置文件的hive.server2.long.polling.timeout参数，在hive-site.xml查看这个值是多少。
1 <property> 2 <name>hive.server2.long.polling.timeout</name> 3 <value>5000L</value> 4 <description>Time in milliseconds that HiveServer2 will wait, before responding to asynchronous calls that use long polling</description> 5 </property>
* 可以看到这个参数对应的值是5000L，回头看看抛出异常的方法，发现if语句的判断根本没有L这个单位，到这就明白了原来是配置文件错是一个BUG，把配置文件这个参数值单位修改为ms，问题解决。
1 <property> 2 <name>hive.server2.long.polling.timeout</name> 3 <value>5000ms</value> 4 <description>Time in milliseconds that HiveServer2 will wait, before responding to asynchronous calls that use long polling</description> 5 </property>
使用的版本是：hive-0.13.1-cdh5.2.1，已经确认后续的版本已经修复这个BUG。