HDFS-7122. Use of ThreadLocal<Random> results in poor block placement. (wang)
(cherry picked from commit d7086c563ff2847c415913ac625b2a557eeccbdd)
This commit is contained in:
parent
9bc676aa6e
commit
47ddaee1db
|
@ -674,27 +674,11 @@ public class NetworkTopology {
|
|||
return node1.getParent()==node2.getParent();
|
||||
}
|
||||
|
||||
private static final ThreadLocal<Random> r = new ThreadLocal<Random>();
|
||||
|
||||
/**
|
||||
* Getter for thread-local Random, which provides better performance than
|
||||
* a shared Random (even though Random is thread-safe).
|
||||
*
|
||||
* @return Thread-local Random.
|
||||
*/
|
||||
protected Random getRandom() {
|
||||
Random rand = r.get();
|
||||
if (rand == null) {
|
||||
rand = new Random();
|
||||
r.set(rand);
|
||||
}
|
||||
return rand;
|
||||
}
|
||||
private static final Random r = new Random();
|
||||
|
||||
@VisibleForTesting
|
||||
void setRandomSeed(long seed) {
|
||||
Random rand = getRandom();
|
||||
rand.setSeed(seed);
|
||||
r.setSeed(seed);
|
||||
}
|
||||
|
||||
/** randomly choose one node from <i>scope</i>
|
||||
|
@ -746,7 +730,7 @@ public class NetworkTopology {
|
|||
"Failed to find datanode (scope=\"" + String.valueOf(scope) +
|
||||
"\" excludedScope=\"" + String.valueOf(excludedScope) + "\").");
|
||||
}
|
||||
int leaveIndex = getRandom().nextInt(numOfDatanodes);
|
||||
int leaveIndex = r.nextInt(numOfDatanodes);
|
||||
return innerNode.getLeaf(leaveIndex, node);
|
||||
}
|
||||
|
||||
|
@ -919,11 +903,10 @@ public class NetworkTopology {
|
|||
list.add(node);
|
||||
}
|
||||
|
||||
Random rand = getRandom();
|
||||
int idx = 0;
|
||||
for (List<Node> list: tree.values()) {
|
||||
if (list != null) {
|
||||
Collections.shuffle(list, rand);
|
||||
Collections.shuffle(list, r);
|
||||
for (Node n: list) {
|
||||
nodes[idx] = n;
|
||||
idx++;
|
||||
|
|
|
@ -277,6 +277,9 @@ Release 2.6.0 - UNRELEASED
|
|||
HDFS-6865. Byte array native checksumming on client side
|
||||
(James Thomas via todd)
|
||||
|
||||
HDFS-7122. Use of ThreadLocal<Random> results in poor block placement.
|
||||
(wang)
|
||||
|
||||
BUG FIXES
|
||||
|
||||
HDFS-6823. dfs.web.authentication.kerberos.principal shows up in logs for
|
||||
|
|
Loading…
Reference in New Issue