On 1/6/2011 7:53 AM, Matt Pouttu-Clarke wrote:
Hi All,
I am using Derby as an embedded database within a Hadoop job to lookup
IP geographic info.
http://mpouttuclarke.wordpress.com/2010/12/10/java-embedded-db-for-ip2location-in-hadoop/
The problem is that Hadoop has an option called JVM sharing where more
than one thread may be active in the JVM instance. Since the embedded
option only supports one thread at a time, I have had to turn off JVM
sharing for my IP lookup job (by setting
mapred.job.reuse.jvm.num.tasks to 1).
Embedded definitely supports more than one thread at a time as long as
all of those threads are in the same JVM. Each thread should just have
it's own separate Connection.
