156 lines
5.3 KiB
Python
156 lines
5.3 KiB
Python
# Standard library imports
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from typing import List, Tuple
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import logging
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# Third-party imports
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import boto3
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from botocore.exceptions import NoCredentialsError
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import ray
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import ray.train
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# Local imports
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from s3_reader import S3Reader, AWS_REGION
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from logger_utils import ContextLoggerAdapter
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logger = ContextLoggerAdapter(logging.getLogger(__name__))
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@ray.remote(num_cpus=0.25)
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def _fetch_parquet_metadata(bucket: str, key: str, file_url: str) -> Tuple[str, int]:
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"""Fetch Parquet row count using S3 Select in parallel.
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Uses S3 Select to efficiently count rows in a Parquet file without reading
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the entire file contents, enabling balanced distribution based on row counts.
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Args:
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bucket: S3 bucket name containing the Parquet file
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key: S3 object key for the Parquet file
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file_url: Full S3 URL for logging purposes
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Returns:
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Tuple containing:
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- file_url: Full S3 URL of the processed file
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- row_count: Number of rows in the Parquet file
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"""
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s3_client = boto3.client("s3", region_name=AWS_REGION)
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# Execute S3 Select query to count rows
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query = "SELECT COUNT(*) FROM s3object"
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response = s3_client.select_object_content(
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Bucket=bucket,
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Key=key,
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Expression=query,
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ExpressionType="SQL",
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InputSerialization={"Parquet": {}},
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OutputSerialization={"CSV": {}},
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)
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# Extract row count from response
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row_count = 0
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for event in response["Payload"]:
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if "Records" in event:
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row_count = int(event["Records"]["Payload"].decode("utf-8").strip())
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logger.info(f"File {file_url} has {row_count} rows")
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return file_url, row_count
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class S3ParquetReader(S3Reader):
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"""Extended S3Reader class for Parquet-specific functionality.
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Provides specialized methods for:
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1. Collecting Parquet file metadata (row counts) from S3
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2. Distributing files among workers based on row counts
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3. Managing parallel S3 operations with Ray tasks
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"""
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def _collect_file_info(
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self, bucket: str, prefix: str
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) -> Tuple[List[str], List[int]]:
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"""Collect file URLs and their row counts in parallel using Ray tasks.
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Lists all Parquet files in the specified S3 prefix and launches parallel
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tasks to count rows in each file using S3 Select for efficient metadata
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collection.
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Args:
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bucket: S3 bucket name to list files from
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prefix: S3 prefix to filter files
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Returns:
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Tuple containing:
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- List of file URLs (e.g., "s3://bucket/path/to/file")
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- List of row counts for each file
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"""
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file_urls, _ = self._list_s3_files(bucket, prefix)
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# Launch parallel metadata collection tasks
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tasks = []
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for file_url in file_urls:
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# Extract key from file_url
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key = file_url.replace(f"s3://{bucket}/", "")
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task = _fetch_parquet_metadata.remote(bucket, key, file_url)
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tasks.append(task)
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# Wait for all tasks to complete
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worker_rank = ray.train.get_context().get_world_rank()
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logger.info(
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f"Worker {worker_rank}: Waiting for metadata from {len(tasks)} files..."
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)
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results = ray.get(tasks)
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# Process results
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file_urls, file_rows = zip(*results) if results else ([], [])
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logger.info(
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f"Worker {worker_rank}: Collected metadata for {len(file_urls)} files"
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)
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return list(file_urls), list(file_rows)
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def _get_file_urls(self, url: str) -> List[str]:
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"""Get file URLs from S3 and distribute them among Ray workers.
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Collects file metadata from S3 and distributes files among workers based on
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row counts to ensure balanced workload distribution.
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Args:
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url: S3 URL to list files from (e.g., "s3://bucket/path/to/directory")
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Returns:
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List of S3 URLs assigned to the current Ray worker
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Raises:
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S3CredentialsError: If AWS credentials are not found or invalid
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S3FileError: If there's an error listing files from S3
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"""
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try:
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# Get Ray worker configuration
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worker_rank = ray.train.get_context().get_world_rank()
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num_workers = ray.train.get_context().get_world_size()
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# Parse S3 URL components
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bucket, prefix = self._parse_s3_url(url)
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# Collect file metadata for balanced distribution
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logger.info(
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f"Worker {worker_rank}: Collecting file metadata for balanced distribution"
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)
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file_urls, file_rows = self._collect_file_info(bucket, prefix)
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logger.info(f"Found {len(file_urls)} files in {url}")
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# Distribute files based on row counts
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return self._distribute_files(
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file_urls=file_urls,
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file_weights=file_rows,
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worker_rank=worker_rank,
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num_workers=num_workers,
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weight_unit="rows",
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)
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except NoCredentialsError:
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raise self.S3CredentialsError(
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"AWS credentials not found. Ensure you have configured them."
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)
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except Exception as e:
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raise self.S3FileError(f"Error listing files from {url}: {str(e)}")
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