Dmitriy
I've tested it on hadoop 1.0.0 and 1.0.1. (I don't know which version
cdh3u3 is based off of)
In hadoop-env.sh if I set
HADOOP_TASKTRACKER_OPTS="-Djava.library.path=/usr/blah" the TaskTracker
sees that option. Then it gets passed along to all M/R child tasks on
that node. Can you confirm that your TaskTrackers are actually seeing
the passed option? (through the ps command)
George
On 2012/03/29 5:19, Dmitriy Lyubimov wrote:
Hm. doesn't seem to work for me (with cdh3u3)
I defined
export HADOOP_TASKTRACKER_OPTS="-Djava.library.path=/usr/...."
and it doesn't seem to work (as opposed to when i set is with<final>
property mapred.child.java.opts on the data node).
Still puzzling.
On Tue, Mar 27, 2012 at 7:17 PM, George Datskos
<george.dats...@jp.fujitsu.com> wrote:
Dmitriy,
I just double-checked, and the caveat I stated earlier is incorrect. So,
"-Djava.library.path" set in the client's {mapred.child.java.opts} should
just append to to the "-Djava.library.path" that each TaskTracker has when
creating the library path for each child (M/R) task. So that's even better
I guess.
George
On 2012/03/28 11:06, George Datskos wrote:
Dmitriy,
To deal with different servers having various shared libraries in
different locations, you can simply make sure the _TaskTracker_'s
-Djava.library.path is set correctly on each server. That library path
should be passed along to each child (M/R) task. (in *addition* to the
{mapred.child.java.opts} that you specify on the client-side configuration
options)
One caveat: on the client-side, don't include "-Djava.library.path" or
that path will be passed along to all of the child tasks, overriding
site-specific one you set on the TaskTracker.
George
On 2012/03/28 10:43, Dmitriy Lyubimov wrote:
Hello,
I have a couple of questions regarding mapreduce configurations.
We install various platforms on data nodes that require mixed set of
native libraries.
Part of the problem is that in general case, this software platforms
may be installed into different locations in the backend. (we try to
unify it, but still). What it means, it may require site-specific
-Djava.library.path setting.
I configured individual jvm options (mapred.child.java.opts) on each
node to include specific set of paths. However, i encountered 2
problems:
#1: my setting doesn't go into effect unless I also declare it final
in the data node. It's just being overriden by default -Xmx200 value
from the driver EVEN when i don't set it on the driver at all (and
there seems to be no way to unset it).
However, using "final" spec at the backend creates a problem if some
of numerous jobs we run wishes to override the setting still. The
ideal behavior is if i don't set it in the driver, then backend value
kicks in, otherwise it's driver's value. But i did not find a way to
do that for this particular setting for some reason.Could somebody
clarify the best workaround? thank you.
#2. Ideal behavior would actually be to merge driver-specific and
backend-specific settings. E.g. backend may need to configure specific
software package locations while client may wish sometimes to set heap
etc. Is there a best practice to achieve this effect?
Thank you very much in advance.
-Dmitriy
