PYTHON-3926 Add more information to connection errors and timeouts

pymongo/common.py

@@ -54,9 +54,9 @@
 from pymongo.write_concern import DEFAULT_WRITE_CONCERN, WriteConcern, validate_boolean
 
 if TYPE_CHECKING:
+    from pymongo import MongoClient
     from pymongo.client_session import ClientSession
 
-
 ORDERED_TYPES: Sequence[Type] = (SON, OrderedDict)
 
 # Defaults until we connect to a server and get updated limits.
@@ -793,7 +793,6 @@ def validate_datetime_conversion(option: Any, value: Any) -> Optional[DatetimeCo
     "waitqueuetimeoutms",
 ]
 
-
 _AUTH_OPTIONS = frozenset(["authmechanismproperties"])
 
 
@@ -871,6 +870,37 @@ def _ecoc_coll_name(encrypted_fields: Mapping[str, Any], name: str) -> Any:
 WRITE_CONCERN_OPTIONS = frozenset(["w", "wtimeout", "wtimeoutms", "fsync", "j", "journal"])
 
 
+def _get_timeout_details(client: MongoClient) -> dict[str, Any]:
+    details = {}
+    timeout = client.options.timeout
+    socket_timeout = client.options.pool_options.socket_timeout
+    connect_timeout = client.options.pool_options.connect_timeout
+    topology = client.topology_description.server_descriptions()
+    if timeout:
+        details["timeout"] = timeout * 1000
+    if socket_timeout:
+        details["socketTimeout"] = socket_timeout * 1000
+    if connect_timeout:
+        details["connectTimeout"] = connect_timeout * 1000
+    if topology:
+        details["topology"] = topology
+    return details
+
+
+def format_timeout_details(details: dict[str, Any]) -> str:
+    result = ""
+    if details:
+        result += " (configured timeouts:"
+        for timeout in ["socketTimeout", "timeout", "connectTimeout"]:
+            if timeout in details:
+                result += f" {timeout}: {details[timeout]}ms,"
+        result = result[:-1]
+        result += ")"
+        if "topology" in details:
+            result += f"\nServer topology: {details['topology']}"
+    return result
+
+
 class BaseObject:
     """A base class that provides attributes and methods common
     to multiple pymongo classes.

pymongo/pool.py

@@ -53,6 +53,8 @@
     MIN_POOL_SIZE,
     ORDERED_TYPES,
     WAIT_QUEUE_TIMEOUT,
+    _get_timeout_details,
+    format_timeout_details,
 )
 from pymongo.errors import (
     AutoReconnect,
@@ -379,7 +381,10 @@ def _truncate_metadata(metadata: MutableMapping[str, Any]) -> None:
 
 
 def _raise_connection_failure(
-    address: Any, error: Exception, msg_prefix: Optional[str] = None
+    address: Any,
+    error: Exception,
+    msg_prefix: Optional[str] = None,
+    details: Optional[dict[str, Any]] = None,
 ) -> NoReturn:
     """Convert a socket.error to ConnectionFailure and raise it."""
     host, port = address
@@ -391,13 +396,14 @@ def _raise_connection_failure(
     if msg_prefix:
         msg = msg_prefix + msg
     if isinstance(error, socket.timeout):
-        raise NetworkTimeout(msg) from error
+        print(f"DETAILS: {details}")
+        raise NetworkTimeout(msg + format_timeout_details(details)) from error
     elif isinstance(error, SSLError) and "timed out" in str(error):
         # Eventlet does not distinguish TLS network timeouts from other
         # SSLErrors (https://github.com/eventlet/eventlet/issues/692).
         # Luckily, we can work around this limitation because the phrase
         # 'timed out' appears in all the timeout related SSLErrors raised.
-        raise NetworkTimeout(msg) from error
+        raise NetworkTimeout(msg + format_timeout_details(details)) from error
     else:
         raise AutoReconnect(msg) from error
 
@@ -738,8 +744,12 @@ def apply_timeout(
         if max_time_ms < 0:
             # CSOT: raise an error without running the command since we know it will time out.
             errmsg = f"operation would exceed time limit, remaining timeout:{timeout:.5f} <= network round trip time:{rtt:.5f}"
+            timeout_details = _get_timeout_details(client)
             raise ExecutionTimeout(
-                errmsg, 50, {"ok": 0, "errmsg": errmsg, "code": 50}, self.max_wire_version
+                errmsg + format_timeout_details(timeout_details),
+                50,
+                {"ok": 0, "errmsg": errmsg, "code": 50},
+                self.max_wire_version,
             )
         if cmd is not None:
             cmd["maxTimeMS"] = int(max_time_ms * 1000)
@@ -1549,7 +1559,10 @@ def connect(self, handler: Optional[_MongoClientErrorHandler] = None) -> Connect
                 )
 
             if isinstance(error, (IOError, OSError, SSLError)):
-                _raise_connection_failure(self.address, error)
+                timeout_details = None
+                if handler:
+                    timeout_details = _get_timeout_details(handler.client)
+                _raise_connection_failure(self.address, error, details=timeout_details)
 
             raise