[ https://issues.apache.org/jira/browse/MAPREDUCE-3404?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Eric Payne updated MAPREDUCE-3404: ---------------------------------- Fix Version/s: 0.24.0 > Speculative Execution: speculative map tasks launched even if > -Dmapreduce.map.speculative=false > ----------------------------------------------------------------------------------------------- > > Key: MAPREDUCE-3404 > URL: https://issues.apache.org/jira/browse/MAPREDUCE-3404 > Project: Hadoop Map/Reduce > Issue Type: Bug > Components: job submission, mrv2 > Affects Versions: 0.23.0 > Environment: Hadoop version is: Hadoop 0.23.0.1110031628 > 10 node test cluster > Reporter: patrick white > Assignee: Eric Payne > Priority: Critical > Fix For: 0.23.0, 0.23.1, 0.24.0 > > Attachments: MAPREDUCE-3404.1.txt, MAPREDUCE-3404.2.txt > > > When forcing a mapper to take significantly longer than other map tasks, > speculative map tasks are > launched even if the mapreduce.job.maps.speculative.execution parameter is > set to 'false'. > Testcase: ran default WordCount job with spec execution set to false for both > map and reduce but still saw a fifth mapper > task launch, ran job as follows: > hadoop --config <config> jar /tmp/testphw/wordcount.jar WordCount > -Dmapreduce.job.maps.speculative.execution=false > -Dmapreduce.job.reduces.speculative.execution=false > /tmp/test_file_of_words* /tmp/file_of_words.out > Input data was 4 text files >hdfs blocksize, with same word pattern plus one > diff text line in each file, fourth > file was 4 times as large as others: > hadoop --config <config> fs -ls /tmp > Found 5 items > drwxr-xr-x - user hdfs 0 2011-10-20 16:17 /tmp/file_of_words.out > -rw-r--r-- 3 user hdfs 62800021 2011-10-20 14:45 /tmp/test_file_of_words1 > -rw-r--r-- 3 user hdfs 62800024 2011-10-20 14:46 /tmp/test_file_of_words2 > -rw-r--r-- 3 user hdfs 62800024 2011-10-20 14:46 /tmp/test_file_of_words3 > -rw-r--r-- 3 user hdfs 271708312 2011-10-20 15:50 /tmp/test_file_of_words4 > Job launched 5 mappers despite spec exec set to false, output snippet: > org.apache.hadoop.mapreduce.JobCounter > NUM_FAILED_MAPS=1 > TOTAL_LAUNCHED_MAPS=5 > TOTAL_LAUNCHED_REDUCES=1 > RACK_LOCAL_MAPS=5 > SLOTS_MILLIS_MAPS=273540 > SLOTS_MILLIS_REDUCES=212876 > Reran same case as above only set both spec exec params to 'true', same > results only this time the fifth task being > launched is expected since spec exec = true. > job run: > hadoop --config <config> jar /tmp/testphw/wordcount.jar WordCount > -Dmapreduce.job.maps.speculative.execution=true > -Dmapreduce.job.reduces.speculative.execution=true > /tmp/test_file_of_words* /tmp/file_of_words.out > output snippet: > org.apache.hadoop.mapreduce.JobCounter > NUM_FAILED_MAPS=1 > TOTAL_LAUNCHED_MAPS=5 > TOTAL_LAUNCHED_REDUCES=1 > RACK_LOCAL_MAPS=5 > SLOTS_MILLIS_MAPS=279653 > SLOTS_MILLIS_REDUCES=211474 -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira