Hi Srinivas, In addition to Jarcec's excellent advice, perhaps you might find http://archive.cloudera.com/cdh/3/sqoop/SqoopUserGuide.html#_mysql_connection_failurehelpful?
Regards, Kathleen On Sat, May 26, 2012 at 6:54 AM, Jarek Jarcec Cecho <[email protected]>wrote: > Hi Srinivas, > exception "com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: > Communications link failure" is very generic and basically means that there > was something wrong with connecting to the MySQL. Could you share your > entire execution log that was generated with --verbose flag? > > Blindly shooting - it's suspicious that your issue appears only when > certain amount of jobs is generated. MySQL is allowing limiting maximal > number of concurrent connections. I would recommend checking defined > connection limit on MySQL side (by SQL query show variables like > "max_connections";) and compare it to number of created map tasks. In case > that configured maximal value for connections is lower, then you need to > either reconfigure mysql or sqoop (for example limit number of used mappers > with --num-mappers argument or do not import all tables at once). > > Jarcec > > On Sat, May 26, 2012 at 09:40:47AM -0400, Srinivas wrote: > > > > > I have couple of problems that I am running into: > > > > > > 1. I was able to initiate only 5 sqoop jobs parallel which is = > number of datanode's. > > > 2. If i try to invoke more jobs parallel then only 5 jobs are > picked by and the rest of them throwing an error saying > "com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications > link failure" > > > > > > Do you have any idea why this is happening. > > > > > > Also, I have made sure that the mysql allows parallel connections from > datanode's. > > > > > > > > > >
