@Todd,
I am using 1 namenode and 10 datanodes. Replication factor is 3.
These are the details about my test suite. It uses the simple
write code that uses IOUtils.copyBytes() and calculates the response time
for each write for a given number of users(threads).
From namenode, I am running the test suite which calculates the
response time for writing a file for several concurrent users(1 , 4 , 9 ,
20 ). Whatever the file size may be(I tried with 100 MB , 1 GB and 5 GB
files), I find that the response time increases linearly.
These are the results for a 100 MB file.
No of Threads
Response time(milli sec)
1
2199
4
2763
2774
34766
64488
9
3620
4897
5018
9991
65501
124156
183639
243631
314233
20
6702
6784
6985
8987
9202
9271
9925
10752
68237
70878
73469
75261
77507
82061
129942
137098
141822
194199
269353
322328
You can see the write time increases for each thread.
@ Sagar:
I think network is not the issue here. This is a private network
with high bandwidth. Moreover I tried the running the same test suite with
several configurations(pseudo dist mode, 1 NN 1 DN Cluster , 1 NN 3 DN
cluster) in my usual network(typically with low bandwidth) and obtained the
results like above :(
Thanks,
Gokul
_____
From: Todd Lipcon [mailto:t...@cloudera.com]
Sent: Monday, April 12, 2010 8:18 PM
To: hdfs-user@hadoop.apache.org; gok...@huawei.com
Subject: Re: response time increases lineraly for each thread!
Can you be more specific about your benchmark? You're almost certainly being
limited by either outgoing network from your single node, or by disk
throughput on that node (writes will go local in addition to remote replicas
if you are running a DN on the same host)
-Todd
On Mon, Apr 12, 2010 at 7:21 AM, Gokulakannan M <gok...@huawei.com> wrote:
Hi,
When I tested the performance of a 11 node hadoop
cluster(private nw) for the write scenario with several threads, I noticed
that the time for each write increases linearly(what ever the file size may
be).
Actually I'm running these threads as a single process in the
system where namenode is running. I'm getting inconsistent results when I
run this suite each time. The results are fluctuating. What might be the
bottlenecks?
I think running this in parallel by spawning multiple shells
will give consistent result. But running these in the same system will give
exact results??
Any ways to measure the performance correctly?
Appreciated any help in this.
Thanks,
Gokul
--
Todd Lipcon
Software Engineer, Cloudera
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