HADOOP-11572. s3a delete() operation fails during a concurrent delete of child entries.

Contributed by Steve Loughran.

(cherry picked from commit 2ac5aab8d725f761a9f9723471a4426f6b5d78c4)

hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/S3AFileSystem.java

@@ -49,6 +49,7 @@
 import com.amazonaws.services.s3.model.GetObjectMetadataRequest;
 import com.amazonaws.services.s3.model.InitiateMultipartUploadRequest;
 import com.amazonaws.services.s3.model.ListObjectsRequest;
+import com.amazonaws.services.s3.model.MultiObjectDeleteException;
 import com.amazonaws.services.s3.model.ObjectListing;
 import com.amazonaws.services.s3.model.ObjectMetadata;
 import com.amazonaws.services.s3.model.PartETag;
@@ -455,7 +456,8 @@ public void setInputPolicy(S3AInputPolicy inputPolicy) {
    * @param path input path, may be relative to the working dir
    * @return a key excluding the leading "/", or, if it is the root path, ""
    */
-  private String pathToKey(Path path) {
+  @VisibleForTesting
+  String pathToKey(Path path) {
     if (!path.isAbsolute()) {
       path = new Path(workingDir, path);
     }
@@ -1011,11 +1013,26 @@ private void blockRootDelete(String key) throws InvalidRequestException {
    * Increments the {@code OBJECT_DELETE_REQUESTS} and write
    * operation statistics.
    * @param deleteRequest keys to delete on the s3-backend
+   * @throws MultiObjectDeleteException one or more of the keys could not
+   * be deleted.
+   * @throws AmazonClientException amazon-layer failure.
    */
-  private void deleteObjects(DeleteObjectsRequest deleteRequest) {
+  private void deleteObjects(DeleteObjectsRequest deleteRequest)
+      throws MultiObjectDeleteException, AmazonClientException {
     incrementWriteOperations();
     incrementStatistic(OBJECT_DELETE_REQUESTS, 1);
+    try {
       s3.deleteObjects(deleteRequest);
+    } catch (MultiObjectDeleteException e) {
+      // one or more of the operations failed.
+      List<MultiObjectDeleteException.DeleteError> errors = e.getErrors();
+      LOG.error("Partial failure of delete, {} errors", errors.size(), e);
+      for (MultiObjectDeleteException.DeleteError error : errors) {
+        LOG.error("{}: \"{}\" - {}",
+            error.getKey(), error.getCode(), error.getMessage());
+      }
+      throw e;
+    }
   }
 
   /**
@@ -1225,10 +1242,15 @@ public void incrementPutProgressStatistics(String key, long bytes) {
    * @param deleteFakeDir indicates whether this is for deleting fake dirs
    * @throws InvalidRequestException if the request was rejected due to
    * a mistaken attempt to delete the root directory.
+   * @throws MultiObjectDeleteException one or more of the keys could not
+   * be deleted in a multiple object delete operation.
+   * @throws AmazonClientException amazon-layer failure.
    */
-  private void removeKeys(List<DeleteObjectsRequest.KeyVersion> keysToDelete,
+  @VisibleForTesting
+  void removeKeys(List<DeleteObjectsRequest.KeyVersion> keysToDelete,
       boolean clearKeys, boolean deleteFakeDir)
-      throws AmazonClientException, InvalidRequestException {
+      throws MultiObjectDeleteException, AmazonClientException,
+      InvalidRequestException {
     if (keysToDelete.isEmpty()) {
       // exit fast if there are no keys to delete
       return;

hadoop-tools/hadoop-aws/src/site/markdown/tools/hadoop-aws/index.md

@@ -1874,6 +1874,31 @@ Consult [Cleaning up After Incremental Upload Failures](#s3a_multipart_purge) fo
 details on how the multipart purge timeout can be set. If multipart uploads
 are failing with the message above, it may be a sign that this value is too low.
 
+### `MultiObjectDeleteException` during delete or rename of files
+
+```
+Exception in thread "main" com.amazonaws.services.s3.model.MultiObjectDeleteException:
+    Status Code: 0, AWS Service: null, AWS Request ID: null, AWS Error Code: null,
+    AWS Error Message: One or more objects could not be deleted, S3 Extended Request ID: null
+  at com.amazonaws.services.s3.AmazonS3Client.deleteObjects(AmazonS3Client.java:1745)
+```
+This happens when trying to delete multiple objects, and one of the objects
+could not be deleted. It *should not occur* just because the object is missing.
+More specifically: at the time this document was written, we could not create
+such a failure.
+
+It will occur if the caller lacks the permission to delete any of the objects.
+
+Consult the log to see the specifics of which objects could not be deleted.
+Do you have permission to do so?
+
+If this operation is failing for reasons other than the caller lacking
+permissions:
+
+1. Try setting `fs.s3a.multiobjectdelete.enable` to `false`.
+1. Consult [HADOOP-11572](https://issues.apache.org/jira/browse/HADOOP-11572)
+for up to date advice.
+
 ### When writing to S3A, HTTP Exceptions logged at info from `AmazonHttpClient`
 
 ```

hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/ITestS3AFailureHandling.java

@@ -18,17 +18,24 @@
 
 package org.apache.hadoop.fs.s3a;
 
+import com.amazonaws.services.s3.model.DeleteObjectsRequest;
+import com.amazonaws.services.s3.model.MultiObjectDeleteException;
+import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.FSDataInputStream;
 import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.InvalidRequestException;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.test.LambdaTestUtils;
 
+import org.junit.Assume;
 import org.junit.Test;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.io.EOFException;
 import java.io.FileNotFoundException;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.concurrent.Callable;
 
 import static org.apache.hadoop.fs.contract.ContractTestUtils.*;
@@ -41,6 +48,13 @@ public class ITestS3AFailureHandling extends AbstractS3ATestBase {
   private static final Logger LOG =
       LoggerFactory.getLogger(ITestS3AFailureHandling.class);
 
+  @Override
+  protected Configuration createConfiguration() {
+    Configuration conf = super.createConfiguration();
+    S3ATestUtils.disableFilesystemCaching(conf);
+    conf.setBoolean(Constants.ENABLE_MULTI_DELETE, true);
+    return conf;
+  }
   @Test
   public void testReadFileChanged() throws Throwable {
     describe("overwrite a file with a shorter one during a read, seek");
@@ -127,4 +141,41 @@ private void assertIsEOF(String operation, int readResult) {
     assertEquals("Expected EOF from "+ operation
         + "; got char " + (char) readResult, -1, readResult);
   }
+
+  @Test
+  public void testMultiObjectDeleteNoFile() throws Throwable {
+    describe("Deleting a missing object");
+    removeKeys(getFileSystem(), "ITestS3AFailureHandling/missingFile");
+  }
+
+  private void removeKeys(S3AFileSystem fileSystem, String... keys)
+      throws InvalidRequestException {
+    List<DeleteObjectsRequest.KeyVersion> request = new ArrayList<>(
+        keys.length);
+    for (String key : keys) {
+      request.add(new DeleteObjectsRequest.KeyVersion(key));
+    }
+    fileSystem.removeKeys(request, false, false);
+  }
+
+  @Test
+  public void testMultiObjectDeleteSomeFiles() throws Throwable {
+    Path valid = path("ITestS3AFailureHandling/validFile");
+    touch(getFileSystem(), valid);
+    NanoTimer timer = new NanoTimer();
+    removeKeys(getFileSystem(), getFileSystem().pathToKey(valid),
+        "ITestS3AFailureHandling/missingFile");
+    timer.end("removeKeys");
+  }
+
+  @Test(expected = MultiObjectDeleteException.class)
+  public void testMultiObjectDeleteNoPermissions() throws Throwable {
+    Configuration conf = getConfiguration();
+    String csvFile = conf.getTrimmed(KEY_CSVTEST_FILE, DEFAULT_CSVTEST_FILE);
+    Assume.assumeTrue("CSV test file is not the default",
+        DEFAULT_CSVTEST_FILE.equals(csvFile));
+    Path testFile = new Path(csvFile);
+    S3AFileSystem fs = (S3AFileSystem)FileSystem.newInstance(testFile.toUri(), conf);
+    removeKeys(fs, fs.pathToKey(testFile));
+  }
 }