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Posted to common-issues@hadoop.apache.org by GitBox <gi...@apache.org> on 2020/07/29 07:14:32 UTC
[GitHub] [hadoop] szetszwo commented on a change in pull request #2165: HDFS-15481. Ordered snapshot deletion: garbage collect deleted snapshots
szetszwo commented on a change in pull request #2165:
URL: https://github.com/apache/hadoop/pull/2165#discussion_r461248171
##########
File path: hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/snapshot/SnapshotDeletionGc.java
##########
@@ -0,0 +1,107 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hdfs.server.namenode.snapshot;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
+import org.apache.hadoop.util.StringUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.Timer;
+import java.util.TimerTask;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+
+import static org.apache.hadoop.hdfs.server.namenode.snapshot.SnapshotManager.DFS_NAMENODE_SNAPSHOT_DELETION_ORDERED_GC_PERIOD_MS;
+import static org.apache.hadoop.hdfs.server.namenode.snapshot.SnapshotManager.DFS_NAMENODE_SNAPSHOT_DELETION_ORDERED_GC_PERIOD_MS_DEFAULT;
+
+public class SnapshotDeletionGc {
+ public static final Logger LOG = LoggerFactory.getLogger(
+ SnapshotDeletionGc.class);
+
+ private final FSNamesystem namesystem;
+ private final int deletionOrderedGcPeriodMs;
+ private final AtomicReference<Timer> timer = new AtomicReference<>();
+
+ public SnapshotDeletionGc(FSNamesystem namesystem, Configuration conf) {
+ this.namesystem = namesystem;
+
+ this.deletionOrderedGcPeriodMs = conf.getInt(
+ DFS_NAMENODE_SNAPSHOT_DELETION_ORDERED_GC_PERIOD_MS,
+ DFS_NAMENODE_SNAPSHOT_DELETION_ORDERED_GC_PERIOD_MS_DEFAULT);
+ LOG.info("{} = {}", DFS_NAMENODE_SNAPSHOT_DELETION_ORDERED_GC_PERIOD_MS,
+ deletionOrderedGcPeriodMs);
+ }
+
+ public void schedule() {
+ if (timer.get() != null) {
+ return;
+ }
+ final Timer t = new Timer(getClass().getSimpleName(), true);
+ if (timer.compareAndSet(null, t)) {
+ LOG.info("Schedule at fixed rate {}",
+ StringUtils.formatTime(deletionOrderedGcPeriodMs));
+ t.scheduleAtFixedRate(new GcTask(),
+ deletionOrderedGcPeriodMs, deletionOrderedGcPeriodMs);
+ }
+ }
+
+ public void cancel() {
+ final Timer t = timer.getAndSet(null);
+ if (t != null) {
+ LOG.info("cancel");
+ t.cancel();
+ }
+ }
+
+ private void gcDeletedSnapshot(String name) {
+ final Snapshot.Root deleted;
+ namesystem.readLock();
Review comment:
This is a good idea. Let's add the assertion to all the cases when the SnapshotDeletionOrdered feature is enabled.
##########
File path: hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/snapshot/SnapshotManager.java
##########
@@ -629,4 +641,36 @@ public void shutdown() {
s.getRoot().getLocalName(), s.getRoot().getFullPathName(),
s.getRoot().getModificationTime());
}
-}
+
+ Snapshot.Root chooseDeletedSnapshot() {
+ final List<INodeDirectory> dirs = getSnapshottableDirs();
+ Collections.shuffle(dirs);
Review comment:
Sure.
##########
File path: hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
##########
@@ -1284,6 +1288,7 @@ void startCommonServices(Configuration conf, HAContext haContext) throws IOExcep
dir.setINodeAttributeProvider(inodeAttributeProvider);
}
snapshotManager.registerMXBean();
+ snapshotDeletionGc.schedule();
Review comment:
Sure. Thanks for the suggestion.
##########
File path: hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/snapshot/SnapshotManager.java
##########
@@ -382,6 +395,14 @@ public void deleteSnapshot(final INodesInPath iip, final String snapshotName,
EnumSet.of(XAttrSetFlag.CREATE, XAttrSetFlag.REPLACE));
return;
}
+
+ // assert if it is deleting the first snapshot
+ final INodeDirectoryAttributes first = snapshottable.getDiffs().getFirstSnapshotINode();
+ if (snapshot.getRoot() != first) {
+ throw new IllegalStateException("Failed to delete snapshot " + snapshotName
Review comment:
No. gcDeletedSnapshot will end up here.
##########
File path: hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
##########
@@ -7166,6 +7175,29 @@ void deleteSnapshot(String snapshotRoot, String snapshotName,
logAuditEvent(true, operationName, rootPath, null, null);
}
+ public void gcDeletedSnapshot(String snapshotRoot, String snapshotName)
+ throws IOException {
+ final String operationName = "gcDeletedSnapshot";
+ String rootPath = null;
+ final INode.BlocksMapUpdateInfo blocksToBeDeleted;
+
+ checkOperation(OperationCategory.WRITE);
+ writeLock();
+ try {
+ checkOperation(OperationCategory.WRITE);
+ rootPath = Snapshot.getSnapshotPath(snapshotRoot, snapshotName);
+ checkNameNodeSafeMode("Cannot gcDeletedSnapshot for " + rootPath);
+
+ final long now = Time.now();
Review comment:
Let's check if the snapshot isMarkedAsDeleted. The "first snapshot" check is already in the code.
##########
File path: hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/snapshot/SnapshotDeletionGc.java
##########
@@ -0,0 +1,107 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hdfs.server.namenode.snapshot;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
+import org.apache.hadoop.util.StringUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.Timer;
+import java.util.TimerTask;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+
+import static org.apache.hadoop.hdfs.server.namenode.snapshot.SnapshotManager.DFS_NAMENODE_SNAPSHOT_DELETION_ORDERED_GC_PERIOD_MS;
+import static org.apache.hadoop.hdfs.server.namenode.snapshot.SnapshotManager.DFS_NAMENODE_SNAPSHOT_DELETION_ORDERED_GC_PERIOD_MS_DEFAULT;
+
+public class SnapshotDeletionGc {
+ public static final Logger LOG = LoggerFactory.getLogger(
+ SnapshotDeletionGc.class);
+
+ private final FSNamesystem namesystem;
+ private final long deletionOrderedGcPeriodMs;
+ private final AtomicReference<Timer> timer = new AtomicReference<>();
+
+ public SnapshotDeletionGc(FSNamesystem namesystem, Configuration conf) {
+ this.namesystem = namesystem;
+
+ this.deletionOrderedGcPeriodMs = conf.getLong(
+ DFS_NAMENODE_SNAPSHOT_DELETION_ORDERED_GC_PERIOD_MS,
+ DFS_NAMENODE_SNAPSHOT_DELETION_ORDERED_GC_PERIOD_MS_DEFAULT);
+ LOG.info("{} = {}", DFS_NAMENODE_SNAPSHOT_DELETION_ORDERED_GC_PERIOD_MS,
+ deletionOrderedGcPeriodMs);
+ }
+
+ public void schedule() {
+ if (timer.get() != null) {
+ return;
+ }
+ final Timer t = new Timer(getClass().getSimpleName(), true);
+ if (timer.compareAndSet(null, t)) {
+ LOG.info("Schedule at fixed rate {}",
+ StringUtils.formatTime(deletionOrderedGcPeriodMs));
+ t.scheduleAtFixedRate(new GcTask(),
+ deletionOrderedGcPeriodMs, deletionOrderedGcPeriodMs);
+ }
+ }
+
+ public void cancel() {
+ final Timer t = timer.getAndSet(null);
+ if (t != null) {
+ LOG.info("cancel");
+ t.cancel();
+ }
+ }
+
+ private void gcDeletedSnapshot(String name) {
+ final Snapshot.Root deleted;
+ namesystem.readLock();
+ try {
+ deleted = namesystem.getSnapshotManager().chooseDeletedSnapshot();
+ } finally {
+ namesystem.readUnlock();
+ }
+ if (deleted == null) {
+ LOG.trace("{}: no snapshots are marked as deleted.", name);
+ return;
+ }
+
+ final String snapshotRoot = deleted.getRootFullPathName();
+ final String snapshotName = deleted.getLocalName();
+ LOG.info("{}: delete snapshot {} from {}",
+ name, snapshotName, snapshotRoot);
+
+ try {
+ namesystem.gcDeletedSnapshot(snapshotRoot, snapshotName);
+ } catch (Throwable e) {
+ LOG.warn("Failed to gcDeletedSnapshot " + deleted.getFullPathName(), e);
Review comment:
The user could be also deleting the snapshot since we only have read lock earlier. The gcDeletedSnapshot here will fail.
We cannot kill a production system when a snapshot cannot be deleted.
I could change the log to error.
##########
File path: hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/snapshot/SnapshotDeletionGc.java
##########
@@ -0,0 +1,107 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hdfs.server.namenode.snapshot;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
+import org.apache.hadoop.util.StringUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.Timer;
+import java.util.TimerTask;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+
+import static org.apache.hadoop.hdfs.server.namenode.snapshot.SnapshotManager.DFS_NAMENODE_SNAPSHOT_DELETION_ORDERED_GC_PERIOD_MS;
+import static org.apache.hadoop.hdfs.server.namenode.snapshot.SnapshotManager.DFS_NAMENODE_SNAPSHOT_DELETION_ORDERED_GC_PERIOD_MS_DEFAULT;
+
+public class SnapshotDeletionGc {
+ public static final Logger LOG = LoggerFactory.getLogger(
+ SnapshotDeletionGc.class);
+
+ private final FSNamesystem namesystem;
+ private final long deletionOrderedGcPeriodMs;
+ private final AtomicReference<Timer> timer = new AtomicReference<>();
+
+ public SnapshotDeletionGc(FSNamesystem namesystem, Configuration conf) {
+ this.namesystem = namesystem;
+
+ this.deletionOrderedGcPeriodMs = conf.getLong(
+ DFS_NAMENODE_SNAPSHOT_DELETION_ORDERED_GC_PERIOD_MS,
+ DFS_NAMENODE_SNAPSHOT_DELETION_ORDERED_GC_PERIOD_MS_DEFAULT);
+ LOG.info("{} = {}", DFS_NAMENODE_SNAPSHOT_DELETION_ORDERED_GC_PERIOD_MS,
+ deletionOrderedGcPeriodMs);
+ }
+
+ public void schedule() {
+ if (timer.get() != null) {
+ return;
+ }
+ final Timer t = new Timer(getClass().getSimpleName(), true);
+ if (timer.compareAndSet(null, t)) {
+ LOG.info("Schedule at fixed rate {}",
+ StringUtils.formatTime(deletionOrderedGcPeriodMs));
+ t.scheduleAtFixedRate(new GcTask(),
+ deletionOrderedGcPeriodMs, deletionOrderedGcPeriodMs);
+ }
+ }
+
+ public void cancel() {
+ final Timer t = timer.getAndSet(null);
+ if (t != null) {
+ LOG.info("cancel");
+ t.cancel();
+ }
+ }
+
+ private void gcDeletedSnapshot(String name) {
+ final Snapshot.Root deleted;
+ namesystem.readLock();
+ try {
+ deleted = namesystem.getSnapshotManager().chooseDeletedSnapshot();
+ } finally {
Review comment:
Sure
##########
File path: hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/snapshot/SnapshotManager.java
##########
@@ -382,6 +395,14 @@ public void deleteSnapshot(final INodesInPath iip, final String snapshotName,
EnumSet.of(XAttrSetFlag.CREATE, XAttrSetFlag.REPLACE));
return;
}
+
Review comment:
@jnp , what is your thought?
##########
File path: hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/snapshot/SnapshotManager.java
##########
@@ -382,6 +395,14 @@ public void deleteSnapshot(final INodesInPath iip, final String snapshotName,
EnumSet.of(XAttrSetFlag.CREATE, XAttrSetFlag.REPLACE));
return;
}
+
Review comment:
IMO, if the user is delete the first snapshot. We should do it right away. Otherwise, there is no way for the user to free up the resource from the snapshots.
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