Differences
This shows you the differences between two versions of the page.
Both sides previous revision Previous revision Next revision | Previous revision Next revision Both sides next revision | ||
courses:mapreduce-tutorial:step-6 [2012/01/24 23:49] straka |
courses:mapreduce-tutorial:step-6 [2012/01/25 00:11] straka |
||
---|---|---|---|
Line 3: | Line 3: | ||
Probably the most important feature of MapReduce is to run computations distributively. | Probably the most important feature of MapReduce is to run computations distributively. | ||
- | So far all our MR jobs were executed locally. But all of them can be executed on multiple machines. It suffices to add parameter '' | + | So far all our MR jobs were executed locally. But all of them can be executed on multiple machines. It suffices to add parameter '' |
perl script.pl run -c number_of_machines [-w sec_to_wait_after_job_completion] input_directory output_directory | perl script.pl run -c number_of_machines [-w sec_to_wait_after_job_completion] input_directory output_directory | ||
+ | This commands creates a cluster of specified number of machines. Every machine is able to run two mappers and two reducers simultaneously. In order to be able to observe the status of the computation after it ends, parameter '' | ||
+ | |||
+ | When a distributed MR computations is executed, it submits a job to SGE cluster, with the name of the Perl script. The SGE cluster creates 3 files in current directory: | ||
+ | * '' | ||
+ | * '' | ||
+ | * '' | ||
+ | When the computation ends and is waiting because of the '' | ||
+ | |||
+ | ===== Web interface ===== | ||
+ | |||
+ | The cluster master provides a web interface on port 50030 (the port may change in the future). The cluster master address can be found at the first line of '' | ||
+ | |||
+ | The web interface provides a lot of useful informations: | ||
+ | * running, failed and successfully completed jobs | ||
+ | * for running job, current progress and counters of the whole job and also of each mapper and reducer is available | ||
+ | * for any job, the counters and outputs of all mappers and reducers are stored | ||