#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 <honkliu@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