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https://issues.apache.org/jira/browse/HDFS-17646?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17890816#comment-17890816
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ASF GitHub Bot commented on HDFS-17646:
---------------------------------------
Hexiaoqiao commented on code in PR #7120:
URL: https://github.com/apache/hadoop/pull/7120#discussion_r1805979088
##########
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/balancer/Balancer.java:
##########
@@ -461,27 +466,31 @@ private long init(List<DatanodeStorageReport> reports) {
metrics.setNumOfUnderUtilizedNodes(underUtilized.size());
Preconditions.checkState(dispatcher.getStorageGroupMap().size()
- == overUtilized.size() + underUtilized.size() + aboveAvgUtilized.size()
- + belowAvgUtilized.size(),
+ == overUtilizedDiffNum + overUtilized.size() + underUtilized.size()
Review Comment:
a. `overUtilized.size()` = `overUtilizedDiffNum + overUtilized.size()`? so
is it need to change here?
b. Please align the format.
##########
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/balancer/TestBalancerLongRunningTasks.java:
##########
@@ -672,6 +672,97 @@ public void testBalancerWithSortTopNodes() throws
Exception {
assertEquals(900, maxUsage);
}
+ @Test(timeout = 60000)
+ public void testBalancerWithLimitTopNodesNum() throws Exception {
+ final Configuration conf = new HdfsConfiguration();
+ // Init the config (block size to 100)
+ initConf(conf);
+ conf.setInt(DFS_HEARTBEAT_INTERVAL_KEY, 30000);
+
+ final long totalCapacity = 1000L;
+ final int diffBetweenNodes = 50;
+
+ // Set up the nodes with two groups:
+ // 5 over-utilized nodes with 80%, 85%, 90%, 95%, 100% usage
+ // 2 under-utilized nodes with 0%, 5% usage
+ // With sortTopNodes and limitTopNodesNum option, 100% used ones will be
chosen
+ final int numOfOverUtilizedDn = 5;
+ final int numOfUnderUtilizedDn = 2;
+ final int totalNumOfDn = numOfOverUtilizedDn + numOfUnderUtilizedDn;
+ final long[] capacityArray = new long[totalNumOfDn];
+ Arrays.fill(capacityArray, totalCapacity);
+
+ try (MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf)
+ .numDataNodes(totalNumOfDn)
+ .simulatedCapacities(capacityArray)
+ .build()) {
+ cluster.setDataNodesDead();
+ List<DataNode> dataNodes = cluster.getDataNodes();
+ // Create top used nodes
+ for (int i = 0; i < numOfOverUtilizedDn; i++) {
+ // Bring one node alive
+ DataNodeTestUtils.triggerHeartbeat(dataNodes.get(i));
+ DataNodeTestUtils.triggerBlockReport(dataNodes.get(i));
+ // Create nodes with: 80%, 85%, 90%, 95%, 100%
+ int nodeCapacity = (int) totalCapacity - diffBetweenNodes *
(numOfOverUtilizedDn - i - 1);
+ TestBalancer.createFile(cluster, new Path("test_big" + i),
nodeCapacity, (short) 1, 0);
+ cluster.setDataNodesDead();
+ }
+
+ // Create under utilized nodes
+ for (int i = 0; i < numOfUnderUtilizedDn; i++) {
+ // Bring one node alive
+ DataNodeTestUtils.triggerHeartbeat(dataNodes.get(i));
Review Comment:
Here write some data in dataNodes[0] and dataNode[1] again? Not sure if the
capacityUsed percent is as expected. Would you mind to give double check?
##########
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/balancer/Balancer.java:
##########
@@ -461,27 +466,31 @@ private long init(List<DatanodeStorageReport> reports) {
metrics.setNumOfUnderUtilizedNodes(underUtilized.size());
Preconditions.checkState(dispatcher.getStorageGroupMap().size()
- == overUtilized.size() + underUtilized.size() + aboveAvgUtilized.size()
- + belowAvgUtilized.size(),
+ == overUtilizedDiffNum + overUtilized.size() + underUtilized.size()
+ + aboveAvgUtilized.size() + belowAvgUtilized.size(),
"Mismatched number of storage groups");
// return number of bytes to be moved in order to make the cluster balanced
return Math.max(overLoadedBytes, underLoadedBytes);
}
private void sortOverUtilized(Map<Source, Double> overUtilizedPercentage) {
- Preconditions.checkState(overUtilized instanceof List,
- "Collection overUtilized is not a List.");
+ Preconditions.checkState(overUtilized instanceof LinkedList,
+ "Collection overUtilized is not a LinkedList.");
LOG.info("Sorting over-utilized nodes by capacity" +
" to bring down top used datanode capacity faster");
- List<Source> list = (List<Source>) overUtilized;
+ LinkedList<Source> list = (LinkedList<Source>) overUtilized;
list.sort(
(Source source1, Source source2) ->
(Double.compare(overUtilizedPercentage.get(source2),
overUtilizedPercentage.get(source1)))
);
+ int size = overUtilized.size();
Review Comment:
Just suggest to add another one separate function rather than located here
which is `sort` something.
##########
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/balancer/Balancer.java:
##########
@@ -452,6 +456,7 @@ private long init(List<DatanodeStorageReport> reports) {
}
}
+ int overUtilizedDiffNum = Math.max(overUtilized.size() - limitTopNodesNum,
0);
Review Comment:
I didn't get purpose of this changes.
> Add Option to limit Balancer prefer highly utilized nodes num in each
> iteration
> -------------------------------------------------------------------------------
>
> Key: HDFS-17646
> URL: https://issues.apache.org/jira/browse/HDFS-17646
> Project: Hadoop HDFS
> Issue Type: New Feature
> Reporter: Zhaobo Huang
> Assignee: Zhaobo Huang
> Priority: Major
> Labels: pull-request-available
>
> Limit the number of topN nodes to avoid excessive nodes affecting cluster
> stability.
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