From 629d31909fc2f7fbfae7b11ffd96365ecbc22928 Mon Sep 17 00:00:00 2001 From: zeekling Date: Sun, 7 Jul 2024 22:09:21 +0800 Subject: [PATCH] =?UTF-8?q?=E5=A2=9E=E5=8A=A0=E6=B3=A8=E9=87=8A?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../BlockPlacementPolicyDefault.java | 81 ++++++++++--------- 1 file changed, 44 insertions(+), 37 deletions(-) diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockPlacementPolicyDefault.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockPlacementPolicyDefault.java index 9407deae71..84991f93e9 100644 --- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockPlacementPolicyDefault.java +++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockPlacementPolicyDefault.java @@ -213,47 +213,49 @@ DatanodeStorageInfo[] chooseTarget(String src, numOfReplicas = maxNodesAndReplicas[0]; int maxNodesPerRack = maxNodesAndReplicas[1]; - chooseFavouredNodes(src, numOfReplicas, favoredNodes, - favoriteAndExcludedNodes, blocksize, maxNodesPerRack, results, - avoidStaleNodes, storageTypes); + // 选择本地local或者青睐的节点 + chooseFavouredNodes(src, numOfReplicas, favoredNodes, + favoriteAndExcludedNodes, blocksize, maxNodesPerRack, results, + avoidStaleNodes, storageTypes); - if (results.size() < numOfReplicas) { - // Not enough favored nodes, choose other nodes, based on block - // placement policy (HDFS-9393). - numOfReplicas -= results.size(); - for (DatanodeStorageInfo storage : results) { - // add localMachine and related nodes to favoriteAndExcludedNodes - addToExcludedNodes(storage.getDatanodeDescriptor(), - favoriteAndExcludedNodes); - } - DatanodeStorageInfo[] remainingTargets = - chooseTarget(src, numOfReplicas, writer, - new ArrayList(numOfReplicas), false, - favoriteAndExcludedNodes, blocksize, storagePolicy, flags, - storageTypes); - for (int i = 0; i < remainingTargets.length; i++) { - results.add(remainingTargets[i]); - } - } - return getPipeline(writer, - results.toArray(new DatanodeStorageInfo[results.size()])); - } catch (NotEnoughReplicasException nr) { - LOG.debug("Failed to choose with favored nodes (={}), disregard favored" - + " nodes hint and retry.", favoredNodes, nr); - // Fall back to regular block placement disregarding favored nodes hint - return chooseTarget(src, numOfReplicas, writer, - new ArrayList(numOfReplicas), false, - excludedNodes, blocksize, storagePolicy, flags); - } + if (results.size() < numOfReplicas) { + // Not enough favored nodes, choose other nodes, based on block + // placement policy (HDFS-9393). + numOfReplicas -= results.size(); + for (DatanodeStorageInfo storage : results) { + // add localMachine and related nodes to favoriteAndExcludedNodes + addToExcludedNodes(storage.getDatanodeDescriptor(), + favoriteAndExcludedNodes); + } + // 选择其他DN节点 + DatanodeStorageInfo[] remainingTargets = + chooseTarget(src, numOfReplicas, writer, + new ArrayList(numOfReplicas), false, + favoriteAndExcludedNodes, blocksize, storagePolicy, flags, + storageTypes); + for (int i = 0; i < remainingTargets.length; i++) { + results.add(remainingTargets[i]); + } + } + return getPipeline(writer, + results.toArray(new DatanodeStorageInfo[results.size()])); + } catch (NotEnoughReplicasException nr) { + LOG.debug("Failed to choose with favored nodes (={}), disregard favored" + + " nodes hint and retry.", favoredNodes, nr); + // Fall back to regular block placement disregarding favored nodes hint + return chooseTarget(src, numOfReplicas, writer, + new ArrayList(numOfReplicas), false, + excludedNodes, blocksize, storagePolicy, flags); + } } protected void chooseFavouredNodes(String src, int numOfReplicas, - List favoredNodes, - Set favoriteAndExcludedNodes, long blocksize, int maxNodesPerRack, - List results, boolean avoidStaleNodes, - EnumMap storageTypes) - throws NotEnoughReplicasException { - for (int i = 0; i < favoredNodes.size() && results.size() < numOfReplicas; + List favoredNodes, + Set favoriteAndExcludedNodes, long blocksize, int maxNodesPerRack, + List results, boolean avoidStaleNodes, + EnumMap storageTypes) + throws NotEnoughReplicasException { + for (int i = 0; i < favoredNodes.size() && results.size() < numOfReplicas; i++) { DatanodeDescriptor favoredNode = favoredNodes.get(i); // Choose a single node which is local to favoredNode. @@ -541,6 +543,7 @@ protected Node chooseTargetInOrder(int numOfReplicas, throws NotEnoughReplicasException { final int numOfResults = results.size(); if (numOfResults == 0) { + // 如果没有选择过DN节点，优先选择本地节点。 DatanodeStorageInfo storageInfo = chooseLocalStorage(writer, excludedNodes, blocksize, maxNodesPerRack, results, avoidStaleNodes, storageTypes, true); @@ -554,6 +557,7 @@ protected Node chooseTargetInOrder(int numOfReplicas, } final DatanodeDescriptor dn0 = results.get(0).getDatanodeDescriptor(); if (numOfResults <= 1) { + // 如果副本小于1，需要从远端rack上面选择 chooseRemoteRack(1, dn0, excludedNodes, blocksize, maxNodesPerRack, results, avoidStaleNodes, storageTypes); if (--numOfReplicas == 0) { @@ -563,6 +567,7 @@ protected Node chooseTargetInOrder(int numOfReplicas, if (numOfResults <= 2) { final DatanodeDescriptor dn1 = results.get(1).getDatanodeDescriptor(); if (clusterMap.isOnSameRack(dn0, dn1)) { + // 如果前面两个是相同rack，选择远端的rack的DN。 chooseRemoteRack(1, dn0, excludedNodes, blocksize, maxNodesPerRack, results, avoidStaleNodes, storageTypes); } else if (newBlock){ @@ -576,6 +581,7 @@ protected Node chooseTargetInOrder(int numOfReplicas, return writer; } } + // 随机选择DN chooseRandom(numOfReplicas, NodeBase.ROOT, excludedNodes, blocksize, maxNodesPerRack, results, avoidStaleNodes, storageTypes); return writer; @@ -592,6 +598,7 @@ protected DatanodeStorageInfo chooseLocalStorage(Node localMachine, } /** + * 选择本地或者青睐的节点 * Choose storage of local or favored node. * @param localOrFavoredNode local or favored node * @param isFavoredNode if target node is favored node