Hi guys: I noticed that in the call to createSocketForPipeline, there is a
hardcoded length of "2".
//from
sock = createSocketForPipeline(src, 2, dfsClient);
This cascades down to the "getDataNodeReadTimeout" method, resulting in a
multiplier of 2.
//from DFSClient.java
int getDatanodeReadTimeout(int numNodes) {
return dfsClientConf.socketTimeout > 0 ?
(HdfsServerConstants.READ_TIMEOUT_EXTENSION * numNodes +
dfsClientConf.socketTimeout) : 0;
}
I wonder why the pipeline length is "2" as opposed to "1" ? It seems that
transferring a single block should have a pipeline length of 1?
///for example: in the createBlockOutputStream method, we have
s = createSocketForPipeline(nodes[0], nodes.length, dfsClient);
Is the "2", then, just used to add some cushion to the timeout? Or is
something expected to be happening during a block transfer which makes the
pipeline a 2 node, rather than 1 node one?
Maybe I'm misunderstanding something about the way the pipeline works so
thanks for helping and apologies if this question is a little silly.
--
Jay Vyas
http://jayunit100.blogspot.com
