Question

MY Hive Query正在抛出此异常。

Hadoop job information for Stage-1: number of mappers: 6; number of reducers: 1
2013-05-22 12:08:32,634 Stage-1 map = 0%,  reduce = 0%
2013-05-22 12:09:19,984 Stage-1 map = 100%,  reduce = 100%
Ended Job = job_201305221200_0001 with errors
Error during job, obtaining debugging information...
Examining task ID: task_201305221200_0001_m_000007 (and more) from job job_201305221200_0001
Examining task ID: task_201305221200_0001_m_000003 (and more) from job job_201305221200_0001
Examining task ID: task_201305221200_0001_m_000001 (and more) from job job_201305221200_0001

Task with the most failures(4): 
-----
Task ID:
  task_201305221200_0001_m_000001

URL:
  http://ip-10-134-7-119.ap-southeast-1.compute.internal:9100/taskdetails.jsp?jobid=job_201305221200_0001&tipid=task_201305221200_0001_m_000001

Possible error:
  Out of memory due to hash maps used in map-side aggregation.

Solution:
  Currently hive.map.aggr.hash.percentmemory is set to 0.5. Try setting it to a lower value. i.e 'set hive.map.aggr.hash.percentmemory = 0.25;'
-----

Counters:
FAILED: Execution Error, return code 2 from org.apache.hadoop.hive.ql.exec.MapRedTask


    select 
        uri, 
        count(*) as hits 
    from
        iislog
    where 
        substr(cs_cookie,instr(cs_Cookie,'cwc'),30) like '%CWC%'
    and uri like '%.aspx%' 
    and logdate = '2013-02-07' 
    group by uri 
    order by hits Desc;

我在8个EMR核心实例上尝试了这个，在8Gb数据上有1个大型主实例。首先我尝试使用外部表（数据的位置是s3的路径）。之后，我将数据从S3下载到EMR并使用本机配置单元表。但是在他们两个中我都得到了同样的错误。

FYI, i am using regex serde to parse the iislogs.

'org.apache.hadoop.hive.contrib.serde2.RegexSerDe'
               WITH SERDEPROPERTIES (
               "input.regex" ="([0-9-]+) ([^ ]*) ([^ ]*) ([^ ]*) ([^ ]*) ([^ ]*) ([^ ]*) ([^ ]*) (\".*\"|[^ ]*) ([^ ]*) ([^ ]*) ([^ ]*) ([^ ]*) ([^ ]*) (\".*\"|[^ ]*) ([^ ]*) ([^ ]*) ([^ ]*) ([^ ]*) ([^ ]*) ([^ ]*) ([^ ]*) (\".*\"|[^ ]*) ([^ ]*) ([^ ]*) ([^ ]*) ([^ ]*) ([0-9-]+ [0-9:.]+) ([^ ]*) ([^ ]*) (\".*\"|[^ ]*) ([0-9-]+ [0-9:.]+)",
               "output.format.string"="%1$s %2$s %3$s %4$s %5$s %6$s %7$s %8$s %9$s %10$s %11$s %12$s %13$s %14$s %15$s %16$s %17$s %18$s %19$s %20$s %21$s %22$s %23$s %24$s %25$s %26$s %27$s %28$s %29$s %30$s %31$s %32$s")
location 's3://*******';

Answer 1

表的位置与Hive无关。
如果你可以粘贴查询会更好 - 所以可以判断映射器是否正在排序。

无论如何 - 我们需要增加内存量。检查映射任务配置为运行的内存量（mapred.child ...）。至少应该是1G左右。如果这个足够大你可以：
- 如果mapper没有排序：考虑将日志中指示的哈希聚合内存百分比提高到更高的数字
- 如果mapper正在排序 - 只需将任务内存提升到更大的数字。

Answer 2

您是否尝试过在邮件中设置set hive.map.aggr.hash.percentmemory = 0.25;？您可以阅读更多here

由于地图侧聚合中使用的哈希映射而导致内存不足

2 个答案: