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Posted to common-commits@hadoop.apache.org by Apache Wiki <wi...@apache.org> on 2007/10/24 05:04:28 UTC
[Lucene-hadoop Wiki] Update of "hslot" by honkliu

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#FORMAT plain
hslot(1)                      HADOOP                       hslot(1)

NAME
        hslot - Set the maximum number of tasks that can be run at the same
                        time on a specified host on the fly
 
SYNOPSIS
        hslot [-h] [-jt jt1;jt2..] HOSTNAME SLOTNUMBER

DESCRIPTION
        hslot set the TaskTracker's (specified by HOSTNAME) maximum availabe
        slot. With this commands, users can change the currently running task
        numbers dynamically. So the job can get a better performance.

        For example, if the max increased, the tasktracker will be able to get
        new tasks. But to increase the SLOTNUMBER to a big number is insane.  

        For tasktracker that is closed, it's behaved as before. 

        For TaskTracker that is open, There are two situations:
                A:  Increase the slot:
                        TaskTracker will be able to accept new task, the number is
                                MAX - CURRENT_RUNNING. 
                          
                B:  Decrease the slot:
                        Tasks currently running will not be affacted, after a long run,
                        there will at most MAX tasks running. 

        -h
                Display usage information

        -jt jobtracker url link
                Specify the cluster by the jobtracker url link, for example. 
                        -jt hostA:3479;hostB:3479
EXAMPLE
        % hhosts
        HOST    STATUS  MAX     MAP     REDUCE  FAILURE TMP_SPACE
        c0101   ok      8       0       0       0       203M
        c0102   ok      8       0       0       0       553M

        % hslot c0102
        Host <c0102> Task Slots will be set to <4>, please confirm by hhosts/hload

        % hhosts                                                        
        HOST    STATUS  MAX     MAP     REDUCE  FAILURE TMP_SPACE
        c0101   ok      8       0       0       0       203M
        c0102   ok      4       0       0       0       553M

AUTHOR
        Written by Shuguang Liu

REPORT BUGS
        Report bugs to <ho...@hotmail.com>

COPYRIGHT
        Copyright (C) 2005-2010 Shuguang Liu's Inc.

        This file is not a free software, all the source codes are protected
        and will not be released to any body or organization without 
        authority. 

SEE ALSO
        hopen(1), hclose(1), hhosts(1), hload(1)
hslot (hadoop utils) 13.0               September 2007