Thanks Tyler. I just moved the pool and cf which store the connection pool and CF information to have global scope.
Increased the server_list values from 1 to 4. ( i think i can increase
them max to 12 since I have 12 data nodes )
when I created 8 threads using python threading package , I see the
below error.
Exception in thread Thread-3:
Traceback (most recent call last):
File "/usr/common/usg/python/2.7.1-20110310/lib64/python2.7/threading.py",
line 530, in __bootstrap_inner
self.run()
File "my_cc.py", line 20, in run
start_cassandra_client(self.name)
File "my_cc.py", line 33, in start_cassandra_client
cf.get(key)
File
"/global/homes/p/pmantha/mypython_repo/lib/python2.7/site-packages/pycassa/columnfamily.py",
line 652, in get
read_consistency_level or self.read_consistency_level)
File
"/global/homes/p/pmantha/mypython_repo/lib/python2.7/site-packages/pycassa/pool.py",
line 553, in execute
conn = self.get()
File
"/global/homes/p/pmantha/mypython_repo/lib/python2.7/site-packages/pycassa/pool.py",
line 536, in get
raise NoConnectionAvailable(message)
NoConnectionAvailable: ConnectionPool limit of size 5 reached, unable
to obtain connection after 30 seconds
Please have a look at the script attached.. and let me know if I need
to change something.. Please bear with me, if I do something terribly
wrong..
I am running the script on a 8 processor node.
thanks
pradeep
On Thu, Jan 17, 2013 at 4:18 PM, Tyler Hobbs <ty...@datastax.com> wrote:
> ConnectionPools and ColumnFamilies are thread-safe in pycassa, and it's best
> to share them across multiple threads. Of course, when you do that, make
> sure to make the ConnectionPool large enough to support all of the threads
> making queries concurrently. I'm also not sure if you're just omitting
> this, but pycassa's ConnectionPool will only open connections to servers you
> explicitly include in server_list; there's no autodiscovery of other nodes
> going on.
>
> Depending on your network latency, you'll top out on python performance with
> a fairly low number of threads due to the GIL. It's best to use multiple
> processes if you really want to benchmark something.
>
>
> On Thu, Jan 17, 2013 at 6:05 PM, Pradeep Kumar Mantha <pradeep...@gmail.com>
> wrote:
>>
>> Hi,
>>
>> Thanks. I would like to benchmark cassandra with our application so
>> that we understand the details of how the actual benchmarking is done.
>> Not sure, how easy it would be to integrate YCSB with our application.
>>
>> So, i am trying different client interfaces to cassandra.
>>
>> I found
>>
>> for 12 Data Nodes Cassandra cluster and 1 Client Node which run 32
>> threads ( each querying X number of queries ).
>>
>> cassandra-cli took 133 seconds
>> pycassa took 521 seconds.
>>
>> Here is the python pycassa code used to query and passed to each
>> thread....
>>
>> def start_cassandra_client(Threadname):
>> pool = pycassa.ConnectionPool('Blast',
>> server_list=['xxx.xx.xx.xx'])
>> cf = pycassa.ColumnFamily(pool, 'Blast_NR')
>> inp_file=open("pycassa_100%_query")
>> for key in inp_file:
>> key=key.strip()
>> cf.get(key)
>>
>> Does Java clients like Hector/Astynax help here.. I am more
>> comfortable with Python than Java and our existing application is also
>> in Python.
>>
>> thanks
>> pradeep
>>
>>
>> On Thu, Jan 17, 2013 at 2:08 PM, Edward Capriolo <edlinuxg...@gmail.com>
>> wrote:
>> > Wow you managed to do a load test through the cassandra-cli. There
>> > should be
>> > a merit badge for that.
>> >
>> > You should use the built in stress tool or YCSB.
>> >
>> > The CLI has to do much more string conversion then a normal client would
>> > and
>> > it is not built for performance. You will definitely get better numbers
>> > through other means.
>> >
>> > On Thu, Jan 17, 2013 at 2:10 PM, Pradeep Kumar Mantha
>> > <pradeep...@gmail.com>
>> > wrote:
>> >>
>> >> Hi,
>> >>
>> >> I am trying to maximize execution of the number of read queries/second.
>> >>
>> >> Here is my cluster configuration.
>> >>
>> >> Replication - Default
>> >> 12 Data Nodes.
>> >> 16 Client Nodes - used for querying.
>> >>
>> >> Each client node executes 32 threads - each thread executes 76896 read
>> >> queries using cassandra-cli tool.
>> >> i.e all the read queries are stored in a file and that file is
>> >> given to cassandra-cli tool ( using -f option ) which is executed by a
>> >> thread.
>> >> so, total number of queries for 16 client Nodes is 16 * 32 * 76896.
>> >>
>> >> The read queries on each client node submitted at the same time. The
>> >> time taken for 16 * 32 * 76896 read queries is nearly 742 seconds -
>> >> which is nearly 53k transactions/second.
>> >>
>> >> I would like to know if there is any other way/tool through which I
>> >> can improve the number of transactions/second.
>> >> Is the performance affected by cassandra-cli tool?
>> >>
>> >> thanks
>> >> pradeep
>> >
>> >
>
>
>
>
> --
> Tyler Hobbs
> DataStax
pycassa_client.py
Description: Binary data
