On Oct 24, 2012, at 7:58 PM, Yoshiki SATO <yosh...@ci.i.u-tokyo.ac.jp> wrote:
> Thanks for you comments. > >>> If so, my question is if I need NOT to install JDK to the all nodes. In >>> other words is it possible to have a machine used as a worker without JDK >>> installed? >>> >> >> You do not need JDK installed on worker nodes - it only has to be on the >> node where you compile your code. However, we launch a JVM for each process, >> so you must at least have the JVM installed on each worker. This is >> typically included in a base Linux installation (just look for the "java" >> command, usually in /usr/bin), so you usually don't have to do anything >> special (as opposed to installing the JDK, which doesn't usually come in the >> base install) > > Ok, but I meant to say about JVM, because my requirement is to leverage such > nodes as have no JVM supported, for example, Gentoo Linux/SPARC64 as workers. > I thought that the Java binding implementation wraps Open MPI only on the > rank zero side. No, every process executes in Java - your application code IS, after all, in Java. What we mean by the FAQ is that the processes access the underlying MPI operations via a JNI module that translates from Java to the native C implementation. So you must have JVM support on each machine. > This is because the FAQ says: > >> 8. Do the Java bindings impact performance of my non-Java application? >> The Java bindings in Open MPI are completely transparent to all other Open >> MPI users and have zero performance impact on the rest of the code/bindings. That statement is intended to reassure all non-Java users that the Java bindings will in no way impact them. > > > But I realize that this perhaps mentions about the Open MPI applications that > use a Java-enabled Open MPI build. Meantime, the next FAQ is specifying the > possibility of performance penalties for Java applications that use Open MPI. That is correct - as the statement says, *non-Java* applications will see no impact of having Java enabled in the build. Java-based applications see a performance penalty relative to a C-based application. HTH Ralph > > Regards, > --yoshiki > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users
