[GitHub] [hadoop] snehavarma commented on a change in pull request #1925: HADOOP-16948. Support single writer dirs.

[GitBox <gi...@apache.org>]

snehavarma commented on a change in pull request #1925:
URL: https://github.com/apache/hadoop/pull/1925#discussion_r593783701



##########
File path: hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/services/SelfRenewingLease.java
##########
@@ -0,0 +1,218 @@
+/**
+ * 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.fs.azurebfs.services;
+
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.util.concurrent.CancellationException;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.hadoop.thirdparty.com.google.common.util.concurrent.FutureCallback;
+import org.apache.hadoop.thirdparty.com.google.common.util.concurrent.ListenableScheduledFuture;
+import org.apache.hadoop.thirdparty.org.checkerframework.checker.nullness.qual.Nullable;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.apache.hadoop.fs.azurebfs.constants.HttpHeaderConfigurations;
+import org.apache.hadoop.fs.azurebfs.contracts.exceptions.AbfsRestOperationException;
+import org.apache.hadoop.fs.azurebfs.contracts.exceptions.AzureBlobFileSystemException;
+import org.apache.hadoop.io.retry.RetryPolicies;
+import org.apache.hadoop.io.retry.RetryPolicy;
+
+import static org.apache.hadoop.fs.azurebfs.constants.FileSystemConfigurations.INFINITE_LEASE_DURATION;
+import static org.apache.hadoop.fs.azurebfs.services.AbfsErrors.ERR_ACQUIRING_LEASE;
+import static org.apache.hadoop.fs.azurebfs.services.AbfsErrors.ERR_LEASE_FUTURE_EXISTS;
+import static org.apache.hadoop.fs.azurebfs.services.AbfsErrors.ERR_NO_LEASE_THREADS;
+
+/**
+ * An Azure blob lease that automatically renews itself indefinitely by scheduling lease
+ * operations through the ABFS client. Use it to prevent writes to the blob by other processes
+ * that don't have the lease.
+ *
+ * Creating a new Lease object blocks the caller until the Azure blob lease is acquired. It will
+ * retry a fixed number of times before failing if there is a problem acquiring the lease.
+ *
+ * Call free() to release the Lease. If the holder process dies, the lease will time out since it
+ * won't be renewed.
+ */
+public final class SelfRenewingLease {
+  private static final Logger LOG = LoggerFactory.getLogger(SelfRenewingLease.class);
+

Review comment:
       Please check if infinite lease is sufficient for your use case.

##########
File path: hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/services/SelfRenewingLease.java
##########
@@ -0,0 +1,218 @@
+/**
+ * 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.fs.azurebfs.services;
+
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.util.concurrent.CancellationException;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.hadoop.thirdparty.com.google.common.util.concurrent.FutureCallback;
+import org.apache.hadoop.thirdparty.com.google.common.util.concurrent.ListenableScheduledFuture;
+import org.apache.hadoop.thirdparty.org.checkerframework.checker.nullness.qual.Nullable;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.apache.hadoop.fs.azurebfs.constants.HttpHeaderConfigurations;
+import org.apache.hadoop.fs.azurebfs.contracts.exceptions.AbfsRestOperationException;
+import org.apache.hadoop.fs.azurebfs.contracts.exceptions.AzureBlobFileSystemException;
+import org.apache.hadoop.io.retry.RetryPolicies;
+import org.apache.hadoop.io.retry.RetryPolicy;
+
+import static org.apache.hadoop.fs.azurebfs.constants.FileSystemConfigurations.INFINITE_LEASE_DURATION;
+import static org.apache.hadoop.fs.azurebfs.services.AbfsErrors.ERR_ACQUIRING_LEASE;
+import static org.apache.hadoop.fs.azurebfs.services.AbfsErrors.ERR_LEASE_FUTURE_EXISTS;
+import static org.apache.hadoop.fs.azurebfs.services.AbfsErrors.ERR_NO_LEASE_THREADS;
+
+/**
+ * An Azure blob lease that automatically renews itself indefinitely by scheduling lease
+ * operations through the ABFS client. Use it to prevent writes to the blob by other processes
+ * that don't have the lease.
+ *
+ * Creating a new Lease object blocks the caller until the Azure blob lease is acquired. It will
+ * retry a fixed number of times before failing if there is a problem acquiring the lease.
+ *
+ * Call free() to release the Lease. If the holder process dies, the lease will time out since it
+ * won't be renewed.
+ */
+public final class SelfRenewingLease {
+  private static final Logger LOG = LoggerFactory.getLogger(SelfRenewingLease.class);
+
+  static final float LEASE_RENEWAL_PERCENT_OF_DURATION = 0.67f; // Lease renewal percent of duration
+
+  static final int LEASE_ACQUIRE_RETRY_INTERVAL = 10; // Retry interval for acquiring lease in secs
+  static final int LEASE_ACQUIRE_MAX_RETRIES = 7; // Number of retries for acquiring lease
+
+  private final AbfsClient client;
+  private final String path;
+  private final int duration;
+  private final int renewalPeriod;
+
+  // Lease status variables
+  private volatile boolean leaseFreed;
+  private volatile String leaseID = null;
+  private volatile Throwable exception = null;
+  private volatile ListenableScheduledFuture<AbfsRestOperation> future = null;
+
+  public static class LeaseException extends AzureBlobFileSystemException {
+    public LeaseException(Throwable t) {
+      super(ERR_ACQUIRING_LEASE + ": " + t, t);
+    }
+
+    public LeaseException(String s) {
+      super(s);
+    }
+  }
+
+  public SelfRenewingLease(AbfsClient client, String path, int duration) throws AzureBlobFileSystemException {

Review comment:
       Background threads that will renew lease every 67% of lease i.e. 10 seconds for 15 second lease and 40 seconds for 60 second lease will add extra cost to customers

##########
File path: hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/services/SelfRenewingLease.java
##########
@@ -0,0 +1,218 @@
+/**
+ * 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.fs.azurebfs.services;
+
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.util.concurrent.CancellationException;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.hadoop.thirdparty.com.google.common.util.concurrent.FutureCallback;
+import org.apache.hadoop.thirdparty.com.google.common.util.concurrent.ListenableScheduledFuture;
+import org.apache.hadoop.thirdparty.org.checkerframework.checker.nullness.qual.Nullable;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.apache.hadoop.fs.azurebfs.constants.HttpHeaderConfigurations;
+import org.apache.hadoop.fs.azurebfs.contracts.exceptions.AbfsRestOperationException;
+import org.apache.hadoop.fs.azurebfs.contracts.exceptions.AzureBlobFileSystemException;
+import org.apache.hadoop.io.retry.RetryPolicies;
+import org.apache.hadoop.io.retry.RetryPolicy;
+
+import static org.apache.hadoop.fs.azurebfs.constants.FileSystemConfigurations.INFINITE_LEASE_DURATION;
+import static org.apache.hadoop.fs.azurebfs.services.AbfsErrors.ERR_ACQUIRING_LEASE;
+import static org.apache.hadoop.fs.azurebfs.services.AbfsErrors.ERR_LEASE_FUTURE_EXISTS;
+import static org.apache.hadoop.fs.azurebfs.services.AbfsErrors.ERR_NO_LEASE_THREADS;
+
+/**
+ * An Azure blob lease that automatically renews itself indefinitely by scheduling lease
+ * operations through the ABFS client. Use it to prevent writes to the blob by other processes
+ * that don't have the lease.
+ *
+ * Creating a new Lease object blocks the caller until the Azure blob lease is acquired. It will
+ * retry a fixed number of times before failing if there is a problem acquiring the lease.
+ *
+ * Call free() to release the Lease. If the holder process dies, the lease will time out since it
+ * won't be renewed.
+ */
+public final class SelfRenewingLease {
+  private static final Logger LOG = LoggerFactory.getLogger(SelfRenewingLease.class);
+
+  static final float LEASE_RENEWAL_PERCENT_OF_DURATION = 0.67f; // Lease renewal percent of duration
+
+  static final int LEASE_ACQUIRE_RETRY_INTERVAL = 10; // Retry interval for acquiring lease in secs
+  static final int LEASE_ACQUIRE_MAX_RETRIES = 7; // Number of retries for acquiring lease
+
+  private final AbfsClient client;
+  private final String path;
+  private final int duration;
+  private final int renewalPeriod;
+
+  // Lease status variables
+  private volatile boolean leaseFreed;
+  private volatile String leaseID = null;
+  private volatile Throwable exception = null;
+  private volatile ListenableScheduledFuture<AbfsRestOperation> future = null;
+
+  public static class LeaseException extends AzureBlobFileSystemException {
+    public LeaseException(Throwable t) {
+      super(ERR_ACQUIRING_LEASE + ": " + t, t);
+    }
+
+    public LeaseException(String s) {
+      super(s);
+    }
+  }
+
+  public SelfRenewingLease(AbfsClient client, String path, int duration) throws AzureBlobFileSystemException {
+    this.leaseFreed = false;
+    this.client = client;
+    this.path = path;
+    this.duration = duration;
+    this.renewalPeriod = (int) (LEASE_RENEWAL_PERCENT_OF_DURATION * this.duration);
+
+    if (client.getNumLeaseThreads() < 1) {
+      throw new LeaseException(ERR_NO_LEASE_THREADS);
+    }
+
+    // Try to get the lease a specified number of times, else throw an error
+    RetryPolicy retryPolicy = RetryPolicies.retryUpToMaximumCountWithFixedSleep(
+        LEASE_ACQUIRE_MAX_RETRIES, LEASE_ACQUIRE_RETRY_INTERVAL, TimeUnit.SECONDS);
+    acquireLease(retryPolicy, 0, 0);
+
+    while (leaseID == null && exception == null) {
+    }
+    if (exception != null) {
+      LOG.error("Failed to acquire lease on {}", path);
+      throw new LeaseException(exception);
+    }
+
+    if (duration != INFINITE_LEASE_DURATION) {
+      renewLease(renewalPeriod);
+    }
+
+    LOG.debug("Acquired lease {} on {}", leaseID, path);
+  }
+
+  private void acquireLease(RetryPolicy retryPolicy, int numRetries, long delay)
+      throws LeaseException {
+    LOG.debug("Attempting to acquire lease on {}, retry {}", path, numRetries);
+    if (future != null && !future.isDone()) {
+      throw new LeaseException(ERR_LEASE_FUTURE_EXISTS);
+    }
+    future = client.schedule(() -> client.acquireLease(path, duration),
+        delay, TimeUnit.SECONDS);
+    client.addCallback(future, new FutureCallback<AbfsRestOperation>() {
+      @Override
+      public void onSuccess(@Nullable AbfsRestOperation op) {
+        leaseID = op.getResult().getResponseHeader(HttpHeaderConfigurations.X_MS_LEASE_ID);
+        LOG.debug("Acquired lease {} on {}", leaseID, path);
+      }
+
+      @Override
+      public void onFailure(Throwable throwable) {
+        try {
+          if (RetryPolicy.RetryAction.RetryDecision.RETRY
+              == retryPolicy.shouldRetry(null, numRetries, 0, true).action) {
+            LOG.debug("Failed acquire lease on {}, retrying: {}", path, throwable);
+            acquireLease(retryPolicy, numRetries + 1, LEASE_ACQUIRE_RETRY_INTERVAL);
+          } else {
+            exception = throwable;
+          }
+        } catch (Exception e) {
+          exception = throwable;
+        }
+      }
+    });
+  }
+
+  private void renewLease(long delay) {
+    LOG.debug("Attempting to renew lease on {}, renew lease id {}, delay {}", path, leaseID, delay);

Review comment:
       Error handling for cases when append may take more time than lease expiry needs to be added incase there is a finite lease.




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