This PR improves monitoring of pg basebackups. During a backup, it re…

…gularly checks how much data has been uploaded and compares this to the last recorded amount in a persisted progress file. If the upload is progressing, it updates the record with the new data and current time. If the backup has not advanced compared to the previous value, it reports the time elapsed since the last progress and emits stalled metrics. Once a backup is complete, the record is reset.

[SRE-7631]

pghoard/common.py

@@ -15,6 +15,7 @@
 import re
 import tarfile
 import tempfile
+import threading
 import time
 from contextlib import suppress
 from dataclasses import dataclass, field
@@ -24,13 +25,16 @@
 from threading import Thread
 from typing import (TYPE_CHECKING, Any, BinaryIO, Callable, Dict, Final, Optional, Protocol, Tuple, cast)
 
+from pydantic import BaseModel
 from rohmu import IO_BLOCK_SIZE, BaseTransfer, rohmufile
 from rohmu.errors import Error, InvalidConfigurationError
 from rohmu.typing import FileLike, HasName
 
 from pghoard import pgutil
+from pghoard.metrics import Metrics
 
 TAR_METADATA_FILENAME: Final[str] = ".pghoard_tar_metadata.json"
+PROGRESS_FILE: Final[str] = "persisted_progress_file.json"
 
 LOG = logging.getLogger("pghoard.common")
 
@@ -100,6 +104,55 @@ class BaseBackupMode(StrEnum):
     pipe = "pipe"
 
 
+class ProgressData(BaseModel):
+    current_progress: float = 0
+    last_updated_time: float = 0
+
+    @property
+    def age(self) -> float:
+        return time.time() - self.last_updated_time
+
+    def update(self, current_progress: float) -> None:
+        self.current_progress = current_progress
+        self.last_updated_time = time.time()
+
+
+class PersistedProgress(BaseModel):
+    progress: Dict[str, ProgressData] = {}
+    _lock: threading.Lock = threading.Lock()
+
+    @classmethod
+    def read(cls, metrics: Metrics) -> "PersistedProgress":
+        if os.path.exists(PROGRESS_FILE):
+            with open(PROGRESS_FILE, "r") as file:
+                try:
+                    return cls.parse_raw(file.read())
+                except Exception as ex:  # pylint: disable=broad-except
+                    LOG.exception("Failed to read persisted progress file: %r", ex)
+                    metrics.unexpected_exception(ex, where="read_persisted_progress")
+        return cls()
+
+    def write(self, metrics: Metrics):
+        with self._lock:
+            try:
+                with tempfile.NamedTemporaryFile("w", delete=False, dir=os.path.dirname(PROGRESS_FILE)) as temp_file:
+                    temp_file.write(self.json())
+                    temp_path = temp_file.name
+                os.rename(temp_path, PROGRESS_FILE)
+            except Exception as ex:  # pylint: disable=broad-except
+                LOG.exception("Failed to write persisted progress file: %r", ex)
+                metrics.unexpected_exception(ex, where="write_persisted_progress")
+
+    def get(self, key: str) -> ProgressData:
+        self.progress.setdefault(key, ProgressData())
+        return self.progress[key]
+
+    def reset(self, key: str, metrics: Metrics) -> None:
+        if key in self.progress and self.progress[key] != ProgressData():
+            del self.progress[key]
+            self.write(metrics=metrics)
+
+
 def create_pgpass_file(connection_string_or_info):
     """Look up password from the given object which can be a dict or a
     string and write a possible password in a pgpass file;

pghoard/transfer.py

@@ -25,7 +25,7 @@
 from rohmu.typing import Metadata
 
 from pghoard.common import (
-    CallbackEvent, CallbackQueue, FileType, PGHoardThread, Queue, QuitEvent, StrEnum, create_alert_file,
+    CallbackEvent, CallbackQueue, FileType, PersistedProgress, PGHoardThread, Queue, QuitEvent, StrEnum, create_alert_file,
     get_object_storage_config
 )
 from pghoard.fetcher import FileFetchManager
@@ -147,14 +147,32 @@ def untrack_upload_event(self, file_key: str) -> None:
 
     def increment(self, file_key: str, total_bytes_uploaded: float) -> None:
         metric_data = {}
+        persisted_progress = PersistedProgress.read(metrics=self.metrics)
+
         with self._tracked_events_lock:
             if file_key not in self._tracked_events:
                 raise Exception(f"UploadEvent for {file_key} is not being tracked.")
 
             file_type = self._tracked_events[file_key].file_type
             if file_type in (
-                FileType.Basebackup, FileType.Basebackup_chunk, FileType.Basebackup_delta, FileType.Basebackup_delta_chunk
+                FileType.Basebackup,
+                FileType.Basebackup_chunk,
+                FileType.Basebackup_delta,
+                FileType.Basebackup_delta_chunk,
             ):
+                progress_info = persisted_progress.get(file_key)
+                if total_bytes_uploaded > progress_info.current_progress:
+                    progress_info.update(total_bytes_uploaded)
+                    persisted_progress.write(metrics=self.metrics)
+                    self.metrics.gauge("pghoard.basebackup_stalled", 0)
+                else:
+                    stalled_age = progress_info.age
+                    self.metrics.gauge("basebackup_stalled", stalled_age)
+                    self.log.warning(
+                        "Upload for file %s has been stalled for %s seconds.",
+                        file_key,
+                        stalled_age,
+                    )
                 metric_data = {
                     "metric": "pghoard.basebackup_bytes_uploaded",
                     "inc_value": total_bytes_uploaded,
@@ -410,6 +428,13 @@ def run_safe(self):
                 time.monotonic() - start_time
             )
 
+            if file_to_transfer.operation in {TransferOperation.Upload} and filetype in (
+                FileType.Basebackup, FileType.Basebackup_chunk, FileType.Basebackup_delta, FileType.Basebackup_delta_chunk
+            ):
+                if result.success:
+                    persisted_progress = PersistedProgress.read(metrics=self.metrics)
+                    persisted_progress.reset(key, metrics=self.metrics)
+
         self.fetch_manager.stop()
         self.log.debug("Quitting TransferAgent")
 
@@ -513,6 +538,10 @@ def handle_upload(self, site, key, file_to_transfer: UploadEvent):
 
             # Sleep for a bit to avoid busy looping. Increase sleep time if the op fails multiple times
             self.sleep(min(0.5 * 2 ** (file_to_transfer.retry_number - 1), 20))
-
+            if file_to_transfer.file_type in (
+                FileType.Basebackup, FileType.Basebackup_chunk, FileType.Basebackup_delta, FileType.Basebackup_delta_chunk
+            ):
+                persisted_progress = PersistedProgress.read(metrics=self.metrics)
+                persisted_progress.reset(key, metrics=self.metrics)
             self.transfer_queue.put(file_to_transfer)
             return None

test/test_common.py

@@ -9,13 +9,15 @@
 import os
 from pathlib import Path
 from typing import Any, Dict
+from unittest.mock import patch
 
 import pytest
 from mock.mock import Mock
 from rohmu.errors import Error
 
+from pghoard import metrics
 from pghoard.common import (
-    TAR_METADATA_FILENAME, create_pgpass_file, default_json_serialization, download_backup_meta_file,
+    TAR_METADATA_FILENAME, PersistedProgress, create_pgpass_file, default_json_serialization, download_backup_meta_file,
     extract_pg_command_version_string, extract_pghoard_bb_v2_metadata, extract_pghoard_delta_metadata, json_encode,
     pg_major_version, pg_version_string_to_number, write_json_file
 )
@@ -88,6 +90,40 @@ def test_json_serialization(self, tmpdir):
 
         assert ob2 == ob2_
 
+    def test_persisted_progress(self):
+        test_progress_file = "test_progress.json"
+
+        test_data = {
+            "progress": {
+                "0af668268d0fe14c6e269760b08d80a634c421b8381df25f31fbed5e8a8c8d8b": {
+                    "current_progress": 100,
+                    "last_updated_time": 1625072042.123456
+                }
+            }
+        }
+
+        with open(test_progress_file, "w") as file:
+            json.dump(test_data, file)
+
+        with patch("pghoard.common.PROGRESS_FILE", test_progress_file):
+            persisted_progress = PersistedProgress.read(metrics=metrics.Metrics(statsd={}))
+            assert "0af668268d0fe14c6e269760b08d80a634c421b8381df25f31fbed5e8a8c8d8b" in persisted_progress.progress
+            assert persisted_progress.progress["0af668268d0fe14c6e269760b08d80a634c421b8381df25f31fbed5e8a8c8d8b"
+                                               ].current_progress == 100
+            assert persisted_progress.progress["0af668268d0fe14c6e269760b08d80a634c421b8381df25f31fbed5e8a8c8d8b"
+                                               ].last_updated_time == 1625072042.123456
+
+            new_progress = 200
+            progress_info = persisted_progress.get("0af668268d0fe14c6e269760b08d80a634c421b8381df25f31fbed5e8a8c8d8b")
+            progress_info.update(new_progress)
+            persisted_progress.write(metrics=metrics.Metrics(statsd={}))
+
+            updated_progress = PersistedProgress.read(metrics=metrics.Metrics(statsd={}))
+            assert updated_progress.progress["0af668268d0fe14c6e269760b08d80a634c421b8381df25f31fbed5e8a8c8d8b"
+                                             ].current_progress == new_progress
+
+        os.remove(test_progress_file)
+
 
 def test_pg_major_version():
     assert pg_major_version("10") == "10"

test/test_transferagent.py

@@ -15,7 +15,7 @@
 from rohmu.errors import FileNotFoundFromStorageError, StorageError
 
 from pghoard import metrics
-from pghoard.common import CallbackEvent, CallbackQueue, FileType, QuitEvent
+from pghoard.common import (PROGRESS_FILE, CallbackEvent, CallbackQueue, FileType, PersistedProgress, QuitEvent)
 from pghoard.transfer import (BaseTransferEvent, DownloadEvent, TransferAgent, UploadEvent, UploadEventProgressTracker)
 
 # pylint: disable=attribute-defined-outside-init
@@ -316,3 +316,21 @@ def test_handle_metadata_error(self):
             evt = self.transfer_agent.handle_metadata(self.test_site, "foo", "bar")
             assert evt.success is False
             assert isinstance(evt.exception, Exception)
+
+    def test_handle_upload_with_persisted_progress(self):
+        upload_event = UploadEvent(
+            backup_site_name="test_site",
+            file_type=FileType.Basebackup,
+            file_path=Path(self.foo_basebackup_path),
+            source_data=Path(self.foo_basebackup_path),
+            metadata={},
+            file_size=3,
+            callback_queue=CallbackQueue(),
+            remove_after_upload=True
+        )
+
+        self.transfer_agent.handle_upload("test_site", self.foo_basebackup_path, upload_event)
+        updated_progress = PersistedProgress.read(metrics=metrics.Metrics(statsd={}))
+        assert updated_progress.progress[self.foo_basebackup_path].current_progress == 3
+        if os.path.exists(PROGRESS_FILE):
+            os.remove(PROGRESS_FILE)