python

Author: khakhlyuk

python/pyspark/sql/connect/client/retries.py

@@ -19,7 +19,9 @@
 import random
 import time
 import typing
-from typing import Optional, Callable, Generator, List, Type
+from google.rpc import error_details_pb2
+from grpc_status import rpc_status
+from typing import Optional, Callable, Generator, List, Type, cast
 from types import TracebackType
 from pyspark.sql.connect.logging import logger
 from pyspark.errors import PySparkRuntimeError, RetriesExceeded
@@ -45,6 +47,34 @@ class RetryPolicy:
     Describes key aspects of RetryPolicy.
 
     It's advised that different policies are implemented as different subclasses.
+
+    Parameters
+    ----------
+    max_retries: int, optional
+        Maximum number of retries.
+    initial_backoff: int
+        Start value of the exponential backoff.
+    max_backoff: int, optional
+        Maximal value of the exponential backoff.
+    backoff_multiplier: float
+        Multiplicative base of the exponential backoff.
+    jitter: int
+        Sample a random value uniformly from the range [0, jitter] and add it to the backoff.
+    min_jitter_threshold: int
+        Minimal value of the backoff to add random jitter.
+    recognize_server_retry_delay: bool
+        Per gRPC standard, the server can send error messages that contain `RetryInfo` message
+        with `retry_delay` field indicating that the client should wait for at least `retry_delay`
+        amount of time before retrying again, see:
+        https://github.com/googleapis/googleapis/blob/master/google/rpc/error_details.proto#L91
+
+        If this flag is set to true, RetryPolicy will use `RetryInfo.retry_delay` field
+        in the backoff computation. Server's `retry_delay` can override client's `max_backoff`.
+
+        This flag does not change which errors are retried, only how the backoff is computed.
+        `DefaultPolicy` additionally has a rule for retrying any error that contains `RetryInfo`.
+    max_server_retry_delay: int, optional
+        Limit for the server-provided `retry_delay`.
     """
 
     def __init__(
@@ -55,13 +85,17 @@ def __init__(
         backoff_multiplier: float = 1.0,
         jitter: int = 0,
         min_jitter_threshold: int = 0,
+        recognize_server_retry_delay: bool = False,
+        max_server_retry_delay: Optional[int] = None,
     ):
         self.max_retries = max_retries
         self.initial_backoff = initial_backoff
         self.max_backoff = max_backoff
         self.backoff_multiplier = backoff_multiplier
         self.jitter = jitter
         self.min_jitter_threshold = min_jitter_threshold
+        self.recognize_server_retry_delay = recognize_server_retry_delay
+        self.max_server_retry_delay = max_server_retry_delay
         self._name = self.__class__.__name__
 
     @property
@@ -98,7 +132,7 @@ def name(self) -> str:
     def can_retry(self, exception: BaseException) -> bool:
         return self.policy.can_retry(exception)
 
-    def next_attempt(self) -> Optional[int]:
+    def next_attempt(self, exception: Optional[BaseException] = None) -> Optional[int]:
         """
         Returns
         -------
@@ -119,6 +153,14 @@ def next_attempt(self) -> Optional[int]:
                 float(self.policy.max_backoff), wait_time * self.policy.backoff_multiplier
             )
 
+        if exception is not None and self.policy.recognize_server_retry_delay:
+            retry_delay = extract_retry_delay(exception)
+            if retry_delay is not None:
+                logger.debug(f"The server has sent a retry delay of {retry_delay} ms.")
+                if self.policy.max_server_retry_delay is not None:
+                    retry_delay = min(retry_delay, self.policy.max_server_retry_delay)
+                wait_time = max(wait_time, retry_delay)
+
         # Jitter current backoff, after the future backoff was computed
         if wait_time >= self.policy.min_jitter_threshold:
             wait_time += random.uniform(0, self.policy.jitter)
@@ -160,6 +202,7 @@ class Retrying:
     This class is a point of entry into the retry logic.
     The class accepts a list of retry policies and applies them in given order.
     The first policy accepting an exception will be used.
+    If the error was matched by one policy, the other policies will be skipped.
 
     The usage of the class should be as follows:
     for attempt in Retrying(...):
@@ -217,17 +260,18 @@ def _wait(self) -> None:
             return
 
         # Attempt to find a policy to wait with
+        matched_policy = None
         for policy in self._policies:
-            if not policy.can_retry(exception):
-                continue
-
-            wait_time = policy.next_attempt()
+            if policy.can_retry(exception):
+                matched_policy = policy
+                break
+        if matched_policy is not None:
+            wait_time = matched_policy.next_attempt(exception)
             if wait_time is not None:
                 logger.debug(
                     f"Got error: {repr(exception)}. "
-                    + f"Will retry after {wait_time} ms (policy: {policy.name})"
+                    + f"Will retry after {wait_time} ms (policy: {matched_policy.name})"
                 )
-
                 self._sleep(wait_time / 1000)
                 return
 
@@ -274,6 +318,8 @@ def __init__(
         max_backoff: Optional[int] = 60000,
         jitter: int = 500,
         min_jitter_threshold: int = 2000,
+        recognize_server_retry_delay: bool = True,
+        max_server_retry_delay: Optional[int] = 10 * 60 * 1000,  # 10 minutes
     ):
         super().__init__(
             max_retries=max_retries,
@@ -282,6 +328,8 @@ def __init__(
             max_backoff=max_backoff,
             jitter=jitter,
             min_jitter_threshold=min_jitter_threshold,
+            recognize_server_retry_delay=recognize_server_retry_delay,
+            max_server_retry_delay=max_server_retry_delay,
         )
 
     def can_retry(self, e: BaseException) -> bool:
@@ -314,4 +362,29 @@ def can_retry(self, e: BaseException) -> bool:
         if e.code() == grpc.StatusCode.UNAVAILABLE:
             return True
 
+        if extract_retry_info(e) is not None:
+            # All errors messages containing `RetryInfo` should be retried.
+            return True
+
         return False
+
+
+def extract_retry_info(exception: BaseException) -> Optional[error_details_pb2.RetryInfo]:
+    """Extract and return RetryInfo from the grpc.RpcError"""
+    if isinstance(exception, grpc.RpcError):
+        status = rpc_status.from_call(cast(grpc.Call, exception))
+        if status:
+            for d in status.details:
+                if d.Is(error_details_pb2.RetryInfo.DESCRIPTOR):
+                    info = error_details_pb2.RetryInfo()
+                    d.Unpack(info)
+                    return info
+    return None
+
+
+def extract_retry_delay(exception: BaseException) -> Optional[int]:
+    """Extract and return RetryInfo.retry_delay in milliseconds from grpc.RpcError if present."""
+    retry_info = extract_retry_info(exception)
+    if retry_info is not None:
+        return retry_info.retry_delay.ToMilliseconds()
+    return None

python/pyspark/sql/tests/connect/client/test_client.py

@@ -227,35 +227,6 @@ def test_is_closed(self):
         client.close()
         self.assertTrue(client.is_closed)
 
-    def test_retry(self):
-        client = SparkConnectClient("sc://foo/;token=bar")
-
-        total_sleep = 0
-
-        def sleep(t):
-            nonlocal total_sleep
-            total_sleep += t
-
-        try:
-            for attempt in Retrying(client._retry_policies, sleep=sleep):
-                with attempt:
-                    raise TestException("Retryable error", grpc.StatusCode.UNAVAILABLE)
-        except RetriesExceeded:
-            pass
-
-        # tolerated at least 10 mins of fails
-        self.assertGreaterEqual(total_sleep, 600)
-
-    def test_retry_client_unit(self):
-        client = SparkConnectClient("sc://foo/;token=bar")
-
-        policyA = TestPolicy()
-        policyB = DefaultPolicy()
-
-        client.set_retry_policies([policyA, policyB])
-
-        self.assertEqual(client.get_retry_policies(), [policyA, policyB])
-
     def test_channel_builder_with_session(self):
         dummy = str(uuid.uuid4())
         chan = DefaultChannelBuilder(f"sc://foo/;session_id={dummy}")