[
https://issues.apache.org/jira/browse/MAPREDUCE-7341?focusedWorklogId=608340&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-608340
]
ASF GitHub Bot logged work on MAPREDUCE-7341:
---------------------------------------------
Author: ASF GitHub Bot
Created on: 08/Jun/21 08:13
Start Date: 08/Jun/21 08:13
Worklog Time Spent: 10m
Work Description: mukund-thakur commented on a change in pull request
#2971:
URL: https://github.com/apache/hadoop/pull/2971#discussion_r646548513
##########
File path:
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/lib/output/committer/manifest/AbortTaskStage.java
##########
@@ -0,0 +1,63 @@
+/*
+ * 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.mapreduce.lib.output.committer.manifest;
+
+import java.io.IOException;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.apache.hadoop.fs.Path;
+
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.ManifestCommitterStatisticNames.OP_STAGE_TASK_ABORT_TASK;
+
+/**
+ * Abort a task.
+ *
+ * This done just by deleting the task directory.
Review comment:
missing is ?
##########
File path:
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/lib/output/committer/manifest/AbstractJobCommitStage.java
##########
@@ -0,0 +1,548 @@
+/*
+ * 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.mapreduce.lib.output.committer.manifest;
+
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.apache.hadoop.fs.FileAlreadyExistsException;
+import org.apache.hadoop.fs.FileStatus;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.fs.PathIOException;
+import org.apache.hadoop.fs.RemoteIterator;
+import org.apache.hadoop.fs.statistics.impl.IOStatisticsStore;
+import
org.apache.hadoop.mapreduce.lib.output.committer.manifest.files.AbstractManifestData;
+import
org.apache.hadoop.mapreduce.lib.output.committer.manifest.files.TaskManifest;
+import org.apache.hadoop.thirdparty.com.google.common.base.Preconditions;
+import org.apache.hadoop.util.DurationInfo;
+import org.apache.hadoop.util.functional.RemoteIterators;
+
+import static java.util.Objects.requireNonNull;
+import static org.apache.hadoop.fs.statistics.StoreStatisticNames.OP_CREATE;
+import static org.apache.hadoop.fs.statistics.StoreStatisticNames.OP_DELETE;
+import static
org.apache.hadoop.fs.statistics.StoreStatisticNames.OP_GET_FILE_STATUS;
+import static
org.apache.hadoop.fs.statistics.StoreStatisticNames.OP_LIST_STATUS;
+import static org.apache.hadoop.fs.statistics.StoreStatisticNames.OP_MKDIRS;
+import static org.apache.hadoop.fs.statistics.StoreStatisticNames.OP_RENAME;
+import static
org.apache.hadoop.fs.statistics.impl.IOStatisticsBinding.trackDuration;
+import static
org.apache.hadoop.fs.statistics.impl.IOStatisticsBinding.trackDurationOfInvocation;
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.ManifestCommitterConstants.MANIFEST_SUFFIX;
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.ManifestCommitterStatisticNames.OP_LOAD_MANIFEST;
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.ManifestCommitterStatisticNames.OP_RENAME_FILE;
+
+/**
+ * A Stage in Task/Job Commit.
+ * A stage can be executed once only, creating the return value of the
+ * {@link #apply(Object)} method, and, potentially, updating the state of the
+ * store via {@link StoreOperations}.
+ * IOStatistics will also be updated.
+ * Stages are expected to be combined to form the commit protocol.
+ * @param <R> Type of arguments to the stage.
Review comment:
nit: It would be better if we give name like I -> input and R-> return
type.
##########
File path:
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/lib/output/committer/manifest/AbstractJobCommitStage.java
##########
@@ -0,0 +1,548 @@
+/*
+ * 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.mapreduce.lib.output.committer.manifest;
+
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.apache.hadoop.fs.FileAlreadyExistsException;
+import org.apache.hadoop.fs.FileStatus;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.fs.PathIOException;
+import org.apache.hadoop.fs.RemoteIterator;
+import org.apache.hadoop.fs.statistics.impl.IOStatisticsStore;
+import
org.apache.hadoop.mapreduce.lib.output.committer.manifest.files.AbstractManifestData;
+import
org.apache.hadoop.mapreduce.lib.output.committer.manifest.files.TaskManifest;
+import org.apache.hadoop.thirdparty.com.google.common.base.Preconditions;
+import org.apache.hadoop.util.DurationInfo;
+import org.apache.hadoop.util.functional.RemoteIterators;
+
+import static java.util.Objects.requireNonNull;
+import static org.apache.hadoop.fs.statistics.StoreStatisticNames.OP_CREATE;
+import static org.apache.hadoop.fs.statistics.StoreStatisticNames.OP_DELETE;
+import static
org.apache.hadoop.fs.statistics.StoreStatisticNames.OP_GET_FILE_STATUS;
+import static
org.apache.hadoop.fs.statistics.StoreStatisticNames.OP_LIST_STATUS;
+import static org.apache.hadoop.fs.statistics.StoreStatisticNames.OP_MKDIRS;
+import static org.apache.hadoop.fs.statistics.StoreStatisticNames.OP_RENAME;
+import static
org.apache.hadoop.fs.statistics.impl.IOStatisticsBinding.trackDuration;
+import static
org.apache.hadoop.fs.statistics.impl.IOStatisticsBinding.trackDurationOfInvocation;
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.ManifestCommitterConstants.MANIFEST_SUFFIX;
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.ManifestCommitterStatisticNames.OP_LOAD_MANIFEST;
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.ManifestCommitterStatisticNames.OP_RENAME_FILE;
+
+/**
+ * A Stage in Task/Job Commit.
+ * A stage can be executed once only, creating the return value of the
+ * {@link #apply(Object)} method, and, potentially, updating the state of the
+ * store via {@link StoreOperations}.
+ * IOStatistics will also be updated.
+ * Stages are expected to be combined to form the commit protocol.
+ * @param <R> Type of arguments to the stage.
Review comment:
Or maybe consistent with <T, R> of JobStage and FunctionRaisingIOE.
##########
File path:
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/lib/output/committer/manifest/ManifestCommitter.java
##########
@@ -0,0 +1,712 @@
+/*
+ * 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.mapreduce.lib.output.committer.manifest;
+
+import java.io.IOException;
+import java.util.Objects;
+import java.util.concurrent.ExecutorService;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.apache.commons.lang3.tuple.Pair;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.fs.statistics.IOStatisticsSource;
+import org.apache.hadoop.fs.statistics.impl.IOStatisticsStore;
+import org.apache.hadoop.mapreduce.JobContext;
+import org.apache.hadoop.mapreduce.JobStatus;
+import org.apache.hadoop.mapreduce.TaskAttemptContext;
+import org.apache.hadoop.mapreduce.TaskAttemptID;
+import org.apache.hadoop.mapreduce.lib.output.PathOutputCommitter;
+import
org.apache.hadoop.mapreduce.lib.output.committer.manifest.files.ManifestSuccessData;
+import
org.apache.hadoop.mapreduce.lib.output.committer.manifest.files.TaskManifest;
+import
org.apache.hadoop.thirdparty.com.google.common.annotations.VisibleForTesting;
+import
org.apache.hadoop.thirdparty.com.google.common.util.concurrent.ThreadFactoryBuilder;
+import org.apache.hadoop.util.Progressable;
+import org.apache.hadoop.util.concurrent.HadoopExecutors;
+
+import static
org.apache.hadoop.fs.statistics.IOStatisticsLogging.ioStatisticsToPrettyString;
+import static
org.apache.hadoop.fs.statistics.IOStatisticsLogging.logIOStatisticsAtDebug;
+import static
org.apache.hadoop.mapreduce.lib.output.FileOutputCommitter.SUCCESSFUL_JOB_OUTPUT_DIR_MARKER;
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.CleanupJobStage.optionsFromConfig;
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.ManifestCommitterConstants.DEFAULT_CREATE_SUCCESSFUL_JOB_DIR_MARKER;
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.ManifestCommitterConstants.MANIFEST_SUFFIX;
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.ManifestCommitterConstants.OPT_IO_PROCESSORS;
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.ManifestCommitterConstants.OPT_IO_PROCESSORS_DEFAULT;
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.ManifestCommitterConstants.OPT_VALIDATE_OUTPUT;
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.ManifestCommitterConstants.OPT_VALIDATE_OUTPUT_DEFAULT;
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.ManifestCommitterStatisticNames.COMMITTER_TASKS_COMPLETED;
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.ManifestCommitterSupport.buildJobUUID;
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.ManifestCommitterSupport.createIOStatisticsStore;
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.ManifestCommitterSupport.getAppAttemptId;
+
+/**
+ * This is the Intermediate-Manifest committer.
+ */
+public class ManifestCommitter extends PathOutputCommitter implements
+ IOStatisticsSource {
+
+ public static final Logger LOG = LoggerFactory.getLogger(
+ ManifestCommitter.class);
+
+ public static final String TASK_COMMITTER = "task committer";
+
+ public static final String JOB_COMMITTER = "job committer";
+
+ /**
+ * Committer Configuration as extracted from
+ * the job/task context and set in the constructor.
+ *
+ */
+ private final ManifestCommitterConfig baseConfig;
+
+ /**
+ * Destination of the job.
+ */
+ private final Path destinationDir;
+
+ /**
+ * For tasks, the attempt directory.
+ * Null for jobs.
+ */
+ private final Path taskAttemptDir;
+
+ /**
+ * IOStatistics to update.
+ */
+ private final IOStatisticsStore iostatistics;
+
+ /**
+ * The job Manifest Success data; only valid after a job successfully
+ * commits.
+ */
+ private ManifestSuccessData jobSuccessData;
+
+ /**
+ * The task manifest of the task commit.
+ * Null unless this is a task attempt and the
+ * task has successfully been committed.
+ */
+ private TaskManifest taskAttemptCommittedManifest;
+
+ /**
+ * Create a committer.
+ * @param outputPath output path
+ * @param context job/task context
+ * @throws IOException failure.
+ */
+ ManifestCommitter(final Path outputPath,
+ final TaskAttemptContext context) throws IOException {
+ super(outputPath, context);
+ destinationDir = resolveDestinationDirectory(outputPath,
+ context.getConfiguration());
+ iostatistics = createIOStatisticsStore().build();
+ baseConfig = new ManifestCommitterConfig(destinationDir,
+ TASK_COMMITTER,
+ context,
+ iostatistics);
+ taskAttemptDir = baseConfig.getTaskAttemptDir();
+ }
+
+ /**
+ * Create a committer config from the passed in job/task context.
+ * @param isTask is this a task?
+ * @param context context
+ * @return committer config
+ */
+ private ManifestCommitterConfig createCommitterConfig(boolean isTask,
+ JobContext context) {
+ return new ManifestCommitterConfig(
+ getOutputPath(),
+ isTask ? TASK_COMMITTER : JOB_COMMITTER,
+ context,
+ iostatistics);
+ }
+
+ /**
+ * Set up a job through a {@link SetupJobStage}.
+ * @param jobContext Context of the job whose output is being written.
+ * @throws IOException IO Failure.
+ */
+ public void setupJob(final JobContext jobContext) throws IOException {
+ ManifestCommitterConfig committerConfig = createCommitterConfig(false,
+ jobContext);
+ StageConfig stageConfig =
+ committerConfig
+ .createJobStageConfig()
+ .withOperations(createStoreOperations())
+ .build();
+ // set up the job.
+ new SetupJobStage(stageConfig)
+ .apply(committerConfig.getCreateJobMarker());
+ logCommitterStatisticsAtDebug();
+ }
+
+ /**
+ * Set up a task through a {@link SetupTaskStage}.
+ *
+ * @param context task context.
+ * @throws IOException IO Failure.
+ */
+ public void setupTask(final TaskAttemptContext context)
+ throws IOException {
+ StageConfig stageConfig =
+ createCommitterConfig(true, context)
+ .createJobStageConfig()
+ .withOperations(createStoreOperations())
+ .build();
+ // create task attempt dir; delete if present. Or fail?
+ new SetupTaskStage(stageConfig).apply("");
+ logCommitterStatisticsAtDebug();
+ }
+
+ /**
+ * Always return true.
+ * @param context task context.
+ * @return true
+ * @throws IOException IO Failure.
+ */
+ public boolean needsTaskCommit(final TaskAttemptContext context)
+ throws IOException {
+ return true;
+ }
+
+ /**
+ * Failure during Job Commit is not recoverable from.
+ *
+ * @param jobContext
+ * Context of the job whose output is being written.
+ * @return false, always
+ * @throws IOException never
+ */
+ @Override
+ public boolean isCommitJobRepeatable(final JobContext jobContext)
+ throws IOException {
+ return false;
+ }
+
+ /**
+ * Declare that task recovery is not supported.
+ * It would be, if someone added the code *and tests*.
+ * @param jobContext
+ * Context of the job whose output is being written.
+ * @return false, always
+ * @throws IOException never
+ */
+ @Override
+ public boolean isRecoverySupported(final JobContext jobContext)
+ throws IOException {
+ return false;
+ }
+
+ /**
+ *
+ * @param taskContext Context of the task whose output is being recovered
+ * @throws IOException always
+ */
+ @Override
+ public void recoverTask(final TaskAttemptContext taskContext)
+ throws IOException {
+ LOG.warn("Rejecting recoverTask({}) call", taskContext.getTaskAttemptID());
+ throw new IOException("Cannot recover task "
+ + taskContext.getTaskAttemptID());
+ }
+
+ /**
+ * Commit the task.
+ * This is where the task attempt tree list takes place.
+ * @param context task context.
+ * @throws IOException IO Failure.
+ */
+ public void commitTask(final TaskAttemptContext context)
+ throws IOException {
+ ManifestCommitterConfig committerConfig = createCommitterConfig(true,
+ context);
+ StageConfig stageConfig = committerConfig.createJobStageConfig()
+ .withOperations(createStoreOperations())
+ .build();
+ taskAttemptCommittedManifest = new CommitTaskStage(stageConfig)
+ .apply("generate")
+ .getRight();
+ iostatistics.incrementCounter(COMMITTER_TASKS_COMPLETED, 1);
+ logCommitterStatisticsAtDebug();
+ }
+
+ /**
+ * Abort a task.
+ * @param context task context
+ * @throws IOException failure during the delete
+ */
+ public void abortTask(final TaskAttemptContext context)
+ throws IOException {
+ ManifestCommitterConfig committerConfig = createCommitterConfig(true,
+ context);
+ new AbortTaskStage(committerConfig.createJobStageConfig()
+ .withOperations(createStoreOperations())
+ .build())
+ .apply(false);
+ logCommitterStatisticsAtDebug();
+ }
+
+ /**
+ * This is the big job commit stage.
+ * Load the manifests, prepare the destination, rename
+ * the files then cleanup the job directory.
+ * @param jobContext Context of the job whose output is being written.
+ * @throws IOException failure.
+ */
+ @Override
+ public void commitJob(final JobContext jobContext) throws IOException {
+
+ ManifestCommitterConfig committerConfig = createCommitterConfig(false,
+ jobContext);
+
+ try (CloseableTaskSubmitter ioProcs =
+ committerConfig.createSubmitter()) {
+ // the stage config will be shared across all stages.
+ StageConfig stageConfig = committerConfig.createJobStageConfig()
+ .withOperations(createStoreOperations())
+ .withIOProcessors(ioProcs)
Review comment:
Ioprocs are shared accross the whole CommitJobStage which includes
LoadManifest and Rename. But in the docs it is written that, threadpool
shouldn't be shared to avoid deadlocks.
##########
File path:
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/lib/output/committer/manifest/CommitJobStage.java
##########
@@ -0,0 +1,112 @@
+/*
+ * 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.mapreduce.lib.output.committer.manifest;
+
+import java.io.IOException;
+import java.util.List;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.apache.commons.lang3.tuple.Pair;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.fs.statistics.impl.IOStatisticsStore;
+import
org.apache.hadoop.mapreduce.lib.output.committer.manifest.files.ManifestSuccessData;
+import
org.apache.hadoop.mapreduce.lib.output.committer.manifest.files.TaskManifest;
+
+import static org.apache.commons.io.FileUtils.byteCountToDisplaySize;
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.ManifestCommitterStatisticNames.OP_JOB_COMMITTED_BYTES;
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.ManifestCommitterStatisticNames.OP_JOB_COMMITTED_FILES;
+import static
org.apache.hadoop.mapreduce.lib.output.committer.manifest.ManifestCommitterStatisticNames.OP_STAGE_JOB_COMMIT;
+
+/**
+ * Commit the Job.
+ * Arguments (save manifest, validate output)
+ */
Review comment:
It will be easier to understand if we define the input and output
arguments of each stage. For example, in this stage I understand that we are
returing ManifestSuccessData but why List<path>?
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Issue Time Tracking
-------------------
Worklog Id: (was: 608340)
Time Spent: 3h 40m (was: 3.5h)
> Add a task-manifest output committer for Azure and GCS
> ------------------------------------------------------
>
> Key: MAPREDUCE-7341
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-7341
> Project: Hadoop Map/Reduce
> Issue Type: New Feature
> Components: client
> Affects Versions: 3.3.1
> Reporter: Steve Loughran
> Assignee: Steve Loughran
> Priority: Major
> Labels: pull-request-available
> Time Spent: 3h 40m
> Remaining Estimate: 0h
>
> Add a task-manifest output committer for Azure and GCS
> The S3A committers are very popular in Spark on S3, as they are both correct
> and fast.
> The classic FileOutputCommitter v1 and v2 algorithms are all that is
> available for Azure ABFS and Google GCS, and they have limitations.
> The v2 algorithm isn't safe in the presence of failed task attempt commits,
> so we
> recommend the v1 algorithm for Azure. But that is slow because it
> sequentially lists
> then renames files and directories, one-by-one. The latencies of list
> and rename make things slow.
> Google GCS lacks the atomic directory rename required for v1 correctness;
> v2 can be used (which doesn't have the job commit performance limitations),
> but it's not safe.
> Proposed
> * Add a new FileOutputFormat committer which uses an intermediate manifest to
> pass the list of files created by a TA to the job committer.
> * Job committer to parallelise reading these task manifests and submit all the
> rename operations into a pool of worker threads. (also: mkdir, directory
> deletions on cleanup)
> * Use the committer plugin mechanism added for s3a to make this the default
> committer for ABFS
> (i.e. no need to make any changes to FileOutputCommitter)
> * Add lots of IOStatistics instrumentation + logging of operations in the
> JobCommit
> for visibility of where delays are occurring.
> * Reuse the S3A committer _SUCCESS JSON structure to publish IOStats & other
> data
> for testing/support.
> This committer will be faster than the V1 algorithm because of the
> parallelisation, and
> because a manifest written by create-and-rename will be exclusive to a single
> task
> attempt, delivers the isolation which the v2 committer lacks.
> This is not an attempt to do an iceberg/hudi/delta-lake style manifest-only
> format
> for describing the contents of a table; the final output is still a directory
> tree
> which must be scanned during query planning.
> As such the format is still suboptimal for cloud storage -but at least we
> will have
> faster job execution during the commit phases.
>
> Note: this will also work on HDFS, where again, it should be faster than
> the v1 committer. However the target is very much Spark with ABFS and GCS; no
> plans to worry about MR as that simplifies the challenge of dealing with job
> restart (i.e. you don't have to)
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