pnodeRun

pnodeRun(function,[nodes],[addNodeAlias=true])

function is the local function to call. It must not be quoted. It can be a function with no parameters by definition, or a partial application that wraps the orginal function and its parameters to a function with no parameters. It can be a built-in function or a user-defined function.

nodes (optional) is a STRING scalar or vector indicating node alias(es). If not specified, the system will call the function on all active data nodes and compute nodes in the cluster.

addNodeAlias (optional) is a Boolean value specifying whether to add node aliases in results. The default value is true. Set to false if node results already contain aliases.

Call a local function on specified nodes in a cluster in parallel and then merge the results.

• If nodes is specified, the function is called on specified nodes.
• If nodes is not specified,
  • When pnodeRun is called on a compute node within a compute group, function is executed on all compute nodes within the group.
  • Otherwise it is executed on all data nodes and and compute nodes which are not included in any compute groups.

Ex. 1 Call function getChunksMeta without specifying parameters

pnodeRun(getChunksMeta,,false);

Ex. 2 In the following example, the function sum and arguments 1..10 are wrapped into a partial application sum{1..10}.

pnodeRun(sum{1..10}, `nodeA`nodeB);

Ex. 3 pnodeRun is a very convenient tool for cluster management. For example, in a cluster of 4 nodes: "DFS_NODE1", "DFS_NODE2", "DFS_NODE3", and "DFS_NODE4", run the following script on each of the node:

def jobDemo(n){
    s = 0
    for (x in 1 : n) {
        s += sum(sin rand(1.0, 100000000)-0.5)
        print("iteration " + x + " " + s)
    }
    return s
};

submitJob("jobDemo1","job demo", jobDemo, 10);
submitJob("jobDemo2","job demo", jobDemo, 10);
submitJob("jobDemo3","job demo", jobDemo, 10);

To check the status of the most recent 2 completed batch jobs on each of the 4 nodes in the cluster:

pnodeRun(getRecentJobs{2});

pnodeRun(getRecentJobs{2}, `DFS_NODE3`DFS_NODE4);