snvijaya commented on a change in pull request #2246:
URL: https://github.com/apache/hadoop/pull/2246#discussion_r480968643



##########
File path: 
hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/services/AbfsClient.java
##########
@@ -271,10 +272,67 @@ public AbfsRestOperation deleteFilesystem() throws 
AzureBlobFileSystemException
     return op;
   }
 
-  public AbfsRestOperation createPath(final String path, final boolean isFile, 
final boolean overwrite,
-                                      final String permission, final String 
umask,
-                                      final boolean isAppendBlob) throws 
AzureBlobFileSystemException {
+  public AbfsRestOperation createPath(final String path,
+      final boolean isFile,
+      final boolean overwrite,
+      final String permission,
+      final String umask,
+      final boolean isAppendBlob) throws AzureBlobFileSystemException {
+    String operation = isFile
+        ? SASTokenProvider.CREATE_FILE_OPERATION
+        : SASTokenProvider.CREATE_DIRECTORY_OPERATION;
+
+    // HDFS FS defaults overwrite behaviour to true for create file which leads
+    // to majority create API traffic with overwrite=true. In some cases, this
+    // will end in race conditions at backend with parallel operations issued 
to
+    // same path either by means of the customer workload or ABFS driver retry.
+    // Disabling the create overwrite default setting to false should
+    // significantly reduce the chances for such race conditions.
+    boolean isFirstAttemptToCreateWithoutOverwrite = false;
+    if (isFile && overwrite
+        && abfsConfiguration.isDefaultCreateOverwriteDisabled()) {
+      isFirstAttemptToCreateWithoutOverwrite = true;
+    }
+
+    AbfsRestOperation op = null;
+    // Query builder
+    final AbfsUriQueryBuilder abfsUriQueryBuilder = 
createDefaultUriQueryBuilder();
+    abfsUriQueryBuilder.addQuery(QUERY_PARAM_RESOURCE,
+        operation.equals(SASTokenProvider.CREATE_FILE_OPERATION)
+            ? FILE
+            : DIRECTORY);
+    if (isAppendBlob) {
+      abfsUriQueryBuilder.addQuery(QUERY_PARAM_BLOBTYPE, APPEND_BLOB_TYPE);
+    }
+
+    appendSASTokenToQuery(path, operation, abfsUriQueryBuilder);
+
+    try {
+      op = createPathImpl(path, abfsUriQueryBuilder,
+          (isFirstAttemptToCreateWithoutOverwrite ? false : overwrite),
+          permission, umask);
+    } catch (AbfsRestOperationException e) {
+      if ((e.getStatusCode() == HttpURLConnection.HTTP_CONFLICT)
+          && isFirstAttemptToCreateWithoutOverwrite) {
+        isFirstAttemptToCreateWithoutOverwrite = false;
+        // was a first attempt made to create without overwrite. Now try again
+        // with overwrite now.
+        op = createPathImpl(path, abfsUriQueryBuilder, true, permission, 
umask);

Review comment:
       PR has been modified to include the step to fetch eTag to ensure that 
the create overwrite=true retry case is handled too.




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