Sihai Ke created HDFS-14180:
-------------------------------
Summary: Suspect there is a bug in NetworkTopology.java
chooseRandom function.
Key: HDFS-14180
URL: https://issues.apache.org/jira/browse/HDFS-14180
Project: Hadoop HDFS
Issue Type: Bug
Components: hdfs, namenode
Affects Versions: 2.9.2
Reporter: Sihai Ke
During reading the hadoop NetworkTopology.java, I suspect there is a bug in
function
chooseRandom (line 498, hadoop version 2.9.2-RC0),
I think there is a bug in{color:#f79232} code,{color:#333333} ~excludedScope
doesn't mean availableNodes under Scope node, and I also add unit test for this
and get an exception.{color}{color}
{quote}
protected Node chooseRandom(final String scope, String excludedScope,
final Collection<Node> excludedNodes) {
if (excludedScope != null) {
if (scope.startsWith(excludedScope)) {
return null;
}
if (!excludedScope.startsWith(scope)) {
excludedScope = null;
}
}
Node node = getNode(scope);
if (!(node instanceof InnerNode)) {
return excludedNodes != null && excludedNodes.contains(node) ?
null : node;
}
InnerNode innerNode = (InnerNode)node;
int numOfDatanodes = innerNode.getNumOfLeaves();
if (excludedScope == null) {
node = null;
} else {
node = getNode(excludedScope);
if (!(node instanceof InnerNode)) {
numOfDatanodes -= 1;
} else {
numOfDatanodes -= ((InnerNode)node).getNumOfLeaves();
}
}
if (numOfDatanodes <= 0) {
LOG.debug("Failed to find datanode (scope=\"{}\" excludedScope=\"{}\")."
+ " numOfDatanodes={}",
scope, excludedScope, numOfDatanodes);
return null;
}
final int availableNodes;
if (excludedScope == null) {
availableNodes = countNumOfAvailableNodes(scope, excludedNodes);
} else {
availableNodes =
{color:#f79232}countNumOfAvailableNodes("~" + excludedScope,
excludedNodes);{color}
}
LOG.debug("Choosing random from {} available nodes on node {},"
+ " scope={}, excludedScope={}, excludeNodes={}. numOfDatanodes={}.",
availableNodes, innerNode, scope, excludedScope, excludedNodes,
numOfDatanodes);
Node ret = null;
if (availableNodes > 0) {
ret = chooseRandom(innerNode, node, excludedNodes, numOfDatanodes,
availableNodes);
}
LOG.debug("chooseRandom returning {}", ret);
return ret;
}{quote}
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