Why don't you try splitting the big query into smaller ones?
On Fri, Aug 24, 2012 at 10:20 AM, Tim Havens <timhav...@gmail.com> wrote: > > Just curious if you've tried using Hive's explain method to see what IT > thinks of your query. > > > On Fri, Aug 24, 2012 at 9:36 AM, Himanish Kushary <himan...@gmail.com>wrote: > >> Hi, >> >> We have a complex query that involves several left outer joins resulting >> in 8 M/R jobs in Hive.During execution of one of the stages ( after three >> M/R has run) the M/R job fails due to few Reduce tasks failing due to >> inactivity. >> >> Most of the reduce tasks go through fine ( within 3 mins) but the last >> one gets stuck for a long time (> 1 hour) and finally after several >> attempts gets killed due to "failed to report status for 600 seconds. >> Killing!" >> >> What may be causing this issue ? Would hive.script.auto.progress help in >> this case ? As we are not able to get much information from the log files >> how may we approach resolving this ? Will tweaking of any specific M/R >> parameters help ? >> >> The task attempt log shows several lines like this before exiting : >> >> 2012-08-23 19:17:23,848 INFO ExecReducer: ExecReducer: processing 219000000 >> rows: used memory = 408582240 >> 2012-08-23 19:17:30,189 INFO ExecReducer: ExecReducer: processing 220000000 >> rows: used memory = 346110400 >> 2012-08-23 19:17:37,510 INFO ExecReducer: ExecReducer: processing 221000000 >> rows: used memory = 583913576 >> 2012-08-23 19:17:44,829 INFO ExecReducer: ExecReducer: processing 222000000 >> rows: used memory = 513071504 >> 2012-08-23 19:17:47,923 INFO org.apache.hadoop.mapred.FileInputFormat: Total >> input paths to process : 1 >> >> Here are the reduce task counters: >> >> *Map-Reduce Framework* Combine input records0 Combine output records0Reduce >> input groups >> 222,480,335 Reduce shuffle bytes7,726,141,897 Reduce input records >> 222,480,335 Reduce output records0 Spilled Records355,827,191 CPU time >> spent (ms)2,152,160 Physical memory (bytes) snapshot1,182,490,624Virtual >> memory (bytes) snapshot >> 1,694,531,584 Total committed heap usage (bytes)990,052,352 >> >> The tasktracker log gives a thread dump at that time but no exception. >> >> *2012-08-23 20:05:49,319 INFO org.apache.hadoop.mapred.TaskTracker: >> Process Thread Dump: lost task* >> *69 active threads* >> >> --------------------------- >> Thanks & Regards >> Himanish >> > > > > -- > "The whole world is you. Yet you keep thinking there is something else." - > Xuefeng Yicun 822-902 A.D. > > Tim R. Havens > Google Phone: 573.454.1232 > ICQ: 495992798 > ICBM: 37°51'34.79"N 90°35'24.35"W > ham radio callsign: NW0W >
