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@Shixiaowei02 Shixiaowei02 commented Jan 7, 2026

Summary by CodeRabbit

Release Notes

  • New Features
    • Added support for disaggregated inference with distributed KV cache transfers between peer nodes
    • Implemented messaging framework using ZeroMQ for inter-node communication
    • Introduced transfer agent abstraction for efficient memory descriptor handling and synchronization
    • Added session management with state tracking and task polling for bidirectional KV slice transfers

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Signed-off-by: Shixiaowei02 <[email protected]>
@Shixiaowei02 Shixiaowei02 requested a review from a team as a code owner January 7, 2026 09:04
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📝 Walkthrough

Walkthrough

Introduces a disaggregated KV cache transfer subsystem comprising base abstractions for transfer agents, session management for bidirectional KV slice transfer, ZeroMQ-based messaging infrastructure, and transfer agent implementations with optional C++ bindings and Python fallbacks.

Changes

Cohort / File(s) Summary
Base Transfer Abstractions
tensorrt_llm/_torch/disaggregation/base/agent.py
Defines transfer agent interface with optional C++ binding support. Exports TransferOp, MemoryType, MemoryDesc, MemoryDescs, TransferRequest, TransferStatus, BaseTransferAgent, RegMemoryDescs classes/dataclasses and is_cpp_binding_available() function. Includes fallback pure-Python implementations when C++ binding unavailable.
KV Transfer Session Interface
tensorrt_llm/_torch/disaggregation/base/kv_transfer.py
Defines abstract KV slice transfer protocol with KVSlice (dataclass for cache slice with block info), SessionStatus (enum for lifecycle states), SessionState (dataclass for status tracking), SessionArgsBase (base args holder), and abstract base classes TxSessionBase and RxSessionBase for transmit/receive sessions supporting async operations and task polling.
Messaging Infrastructure
tensorrt_llm/_torch/disaggregation/native/messenger.py, tensorrt_llm/_torch/disaggregation/native/utils.py
Implements ZMQ-based messaging layer with MessengerInterface (abstract base), ZMQMessenger (concrete implementation with socket lifecycle, listener thread, graceful stop), context manager support, and helper functions decode_message() and get_local_ip() for network utilities.
Transfer Agent Implementation
tensorrt_llm/_torch/disaggregation/nixl/agent.py
Provides transfer agent implementations: BindingsNixlTransferAgent and BindingsNixlTransferStatus wrapping C++ bindings with memory registration, remote agent handling, and transfer submission; fallback Python-based NixlTransferAgent and NixlTransferStatus using nixl library. Includes is_transfer_agent_binding_available() and internal descriptor conversion helpers.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~30 minutes

🚥 Pre-merge checks | ✅ 1 | ❌ 2
❌ Failed checks (2 warnings)
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✅ Passed checks (1 passed)
Check name Status Explanation
Title check ✅ Passed The title '[TRTLLM-9527][feat] Python transceiver components (step 2)' clearly summarizes the main change - adding Python transceiver components as part of a multi-step feature implementation, properly formatted with JIRA ticket and type.

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Actionable comments posted: 12

🤖 Fix all issues with AI agents
In @tensorrt_llm/_torch/disaggregation/base/agent.py:
- Around line 1-4: Add the required NVIDIA copyright header block at the very
top of this source file (before any imports) using the project’s standard header
template (including SPDX/license tag, year(s), and "NVIDIA CORPORATION &
AFFILIATES" attribution); ensure the header matches other TensorRT-LLM files and
update the year range if needed so the file (agent.py) conforms to the
repository’s licensing/copyright guidelines.
- Line 66: The wait method signature uses Python 3.10 union syntax ("def
wait(self, timeout: float | None = None) -> None") which is incompatible with
the project's Python 3.8+ requirement; change the annotation to use
typing.Optional (e.g., "timeout: Optional[float] = None") and add an import for
Optional from typing if not already present, leaving the method name wait and
behavior unchanged.

In @tensorrt_llm/_torch/disaggregation/base/kv_transfer.py:
- Around line 89-94: The docstring for the abstract method receive is misplaced
after the method body; move the triple-quoted docstring so it immediately
follows the receive(self, slice: KVSlice) -> TaskIdType: signature (so it
becomes the method's docstring), ensure it uses proper triple quotes and
references behavior (async receive slice from the peer, returns TaskIdType, task
state polled via poll_task()), and keep the @abstractmethod decorator and
signature intact.
- Around line 1-9: Add the standard NVIDIA copyright header to the top of this
source file (before any imports/definitions) so it matches other project files;
insert the project's canonical header block (including copyright year, NVIDIA
ownership and any SPDX/license tag your repo uses) at the top of kv_transfer.py
(where DisaggregatedParams is imported) to satisfy the coding guidelines.
- Around line 66-71: The docstring currently sits after the abstract method
signature for send (def send(self, slice: KVSlice) -> TaskIdType) and is
therefore a no-op; move the triple-quoted string into the send method body as
its proper docstring (directly under the signature) so the abstractmethod has an
explanatory docstring describing the async send behavior and that the returned
TaskIdType can be polled via poll_task(); remove the standalone string
expression left after the method signature and ensure the method still respects
@abstractmethod (body can be the docstring alone or followed by raise
NotImplementedError).

In @tensorrt_llm/_torch/disaggregation/native/messenger.py:
- Around line 1-9: Add the standard NVIDIA copyright header to the top of the
tensorrt_llm._torch.disaggregation.native.messenger module (before any imports
or code), matching the project's required header format and year range; ensure
the header appears as the first lines of the file so it precedes the existing
imports and module code.
- Around line 96-104: The ZMQMessenger constructor can leave self._endpoint
uninitialized when endpoint is falsy, causing AttributeError later (e.g., in the
endpoint property); initialize self._endpoint to a default (None or empty
string) before the conditional that checks endpoint, then preserve the existing
logic that sets self._endpoint inside the if/elif branches for "ROUTER"/"REP"
and "DEALER"/"REQ" so the attribute is always defined whether or not an endpoint
was provided.
- Line 81: The endpoint default is evaluated at import time because the f-string
calls get_local_ip() in the function signature; change the __init__ signature to
use endpoint: Optional[str] = None and inside __init__ resolve the default by
computing f"tcp://{get_local_ip()}:*" when endpoint is None (or
validate/overwrite endpoint accordingly). Update any docstring or comments for
the Messenger class/method to reflect that endpoint is now resolved at
instantiation time and ensure references to the parameter in methods use the
instance attribute (e.g., self.endpoint) set from the resolved value.

In @tensorrt_llm/_torch/disaggregation/native/utils.py:
- Around line 1-34: Add the required NVIDIA copyright header to the top of this
source file (the one defining get_local_ip) including the appropriate year of
the latest meaningful modification and the standard NVIDIA header text used
across the project; place it above all imports and code, ensure formatting
matches other TensorRT-LLM files, and update the year if this file was modified
after the existing header template's year.

In @tensorrt_llm/_torch/disaggregation/nixl/agent.py:
- Around line 1-13: Add the required NVIDIA copyright header at the top of the
file before the existing module docstring; update
tensorrt_llm/_torch/disaggregation/nixl/agent.py by inserting the standard
multi-line copyright header as the first lines (above the triple-quoted module
docstring that currently describes NIXL Transfer Agent implementations and
before the import of time and nvtx_range).
- Around line 246-249: The code uses assert to check transfer result in the
block that calls self.agent.transfer(handle); replace the assert with explicit
runtime error handling: inspect the returned status from
self.agent.transfer(handle) and if it equals "ERROR" raise a descriptive
exception (e.g., RuntimeError or a custom TransferError) including context such
as the handle and/or status; otherwise return NixlTransferStatus(self.agent,
handle). Ensure this change is applied where status =
self.agent.transfer(handle) is used (in the method that returns
NixlTransferStatus).
- Around line 217-218: The load_remote_agent method currently accepts a name
parameter but never uses it; update load_remote_agent to forward name to the
nixl library call (call add_remote_agent with both name and agent_desc) if the
Python nixl binding supports a name argument, mirroring
BindingsNixlTransferAgent, or if the binding does not accept a name then add a
short comment/docstring in load_remote_agent explaining why name is
intentionally ignored and that the C++ binding handles naming instead.
🧹 Nitpick comments (11)
tensorrt_llm/_torch/disaggregation/native/utils.py (2)

2-11: socket import is scoped inside try block but used outside.

The socket module is imported at line 3 inside the first try block, but it's used again at lines 27-28 in the third fallback. If the first try block raises an exception before the import succeeds (unlikely but possible), or if it's skipped due to code refactoring, a NameError will occur.

Move import to module level
+import socket
+
+
 def get_local_ip() -> str:
     try:
-        import socket
-
         with socket.socket(socket.AF_INET, socket.SOCK_DGRAM) as s:

23-24: Catching blind Exception silently discards useful diagnostics.

Consider catching a more specific exception (e.g., ImportError for missing netifaces, KeyError, OSError) or at least logging the exception for debugging purposes.

Proposed fix
-    except Exception:
-        pass
+    except (ImportError, KeyError, OSError):
+        pass
tensorrt_llm/_torch/disaggregation/native/messenger.py (3)

121-125: Prefer unpacking over list concatenation.

Using [recipient, *messages] is more idiomatic and slightly more efficient than [recipient] + messages.

Proposed fix
     def send(self, messages: list[bytes], recipient: Optional[bytes] = None):
         if recipient:
-            self._socket.send_multipart([recipient] + messages)
+            self._socket.send_multipart([recipient, *messages])
         else:
             self._socket.send_multipart(messages)

153-158: Broad exception catch may mask programming errors.

Catching all Exception types could hide bugs. Consider being more specific or at least including the exception type in the log message.

Include exception type in error log
                 except zmq.ZMQError as e:
                     logger.error(f"ZMQ Error in listener: {e}")
                     continue
                 except Exception as e:
-                    logger.error(f"Error in listener: {e}")
+                    logger.error(f"Unexpected {type(e).__name__} in listener: {e}")
                     continue

182-183: __del__ calling stop() may cause issues during interpreter shutdown.

During interpreter shutdown, the zmq module or logger may already be garbage collected when __del__ is called, potentially causing errors. Consider wrapping in a try-except or checking if resources are valid.

Proposed fix
     def __del__(self):
-        self.stop()
+        try:
+            self.stop()
+        except Exception:
+            pass  # Suppress errors during interpreter shutdown
tensorrt_llm/_torch/disaggregation/base/kv_transfer.py (2)

49-52: Empty abstract base classes serve no purpose.

SenderBase and ReceiverBase are ABCs with no abstract methods or properties. Consider either adding abstract methods they should define, or using regular base classes if they're just type markers.


55-57: Unused constructor arguments sender and receiver.

The sender and receiver arguments are accepted but never used. If they're intended for future use, consider storing them as instance attributes or adding a comment explaining the intent.

Store the argument for future use
 class TxSessionBase(ABC):
     def __init__(self, sender: SenderBase, args: SessionArgsBase):
+        self._sender = sender
         self._base_args = args

...

 class RxSessionBase(ABC):
     def __init__(self, receiver: ReceiverBase, args: SessionArgsBase):
+        self._receiver = receiver
         self._base_args = args

Also applies to: 78-80

tensorrt_llm/_torch/disaggregation/base/agent.py (1)

31-40: Consider using Enum for TransferOp and MemoryType fallbacks.

Using class attributes with string values works but loses type safety. Consider using Enum to match the likely C++ binding behavior and provide better IDE support.

Example using Enum
+    from enum import Enum
+
-    class TransferOp:
-        READ = "READ"
-        WRITE = "WRITE"
+    class TransferOp(Enum):
+        READ = "READ"
+        WRITE = "WRITE"

-    class MemoryType:
-        DRAM = "DRAM"
-        VRAM = "VRAM"
-        BLK = "BLK"
-        OBJ = "OBJ"
-        FILE = "FILE"
+    class MemoryType(Enum):
+        DRAM = "DRAM"
+        VRAM = "VRAM"
+        BLK = "BLK"
+        OBJ = "OBJ"
+        FILE = "FILE"
tensorrt_llm/_torch/disaggregation/nixl/agent.py (3)

96-101: Type annotation says bytes but code handles str case.

The type hint declares agent_desc: bytes, but line 99 handles the case where it might be a string. Either update the type hint to Union[bytes, str] or remove the isinstance check if only bytes are expected.

Option 1: Update type hint to reflect actual usage
-    def load_remote_agent(self, name: str, agent_desc: bytes):
+    def load_remote_agent(self, name: str, agent_desc: Union[bytes, str]):
         """Load a remote agent by its descriptor (bytes)."""
         # AgentDesc expects std::string which can hold binary data
         desc_str = agent_desc if isinstance(agent_desc, bytes) else agent_desc.encode()

Add Union to imports at the top:

from typing import Union

22-22: Remove unused noqa directives.

Static analysis indicates the # noqa: E402 comments are unnecessary as the E402 rule is not enabled.

Proposed fix
-    import tensorrt_llm.tensorrt_llm_transfer_agent_binding as _agent_binding  # noqa: E402
+    import tensorrt_llm.tensorrt_llm_transfer_agent_binding as _agent_binding

...

-    from nixl import nixl_agent, nixl_agent_config, nixl_xfer_handle  # noqa: E402
+    from nixl import nixl_agent, nixl_agent_config, nixl_xfer_handle

Also applies to: 173-173


186-198: Exponential backoff with sleep is reasonable but consider a maximum iteration count.

The wait loop uses exponential backoff which is good, but there's no maximum iteration limit. In pathological cases, this could loop indefinitely if the status never changes from "PROC".

Add maximum wait time or iteration limit
         def wait(self):
             status = "PROC"
             sleep_time = 0.0001  # 0.1ms
             max_sleep_time = 0.01  # 10ms
+            max_total_wait = 300  # 5 minutes
+            total_waited = 0
             while status == "PROC":
                 status = self.agent.check_xfer_state(self.handle)
                 if status == "ERROR":
                     return False  # transfer failed
-                # sleep(0.1)
                 # sleep to release GIL
                 time.sleep(sleep_time)
+                total_waited += sleep_time
+                if total_waited >= max_total_wait:
+                    return False  # timeout
                 sleep_time = min(sleep_time * 2, max_sleep_time)
             return True
📜 Review details

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 7e88212 and ad69bd0.

📒 Files selected for processing (9)
  • tensorrt_llm/_torch/disaggregation/__init__.py
  • tensorrt_llm/_torch/disaggregation/base/__init__.py
  • tensorrt_llm/_torch/disaggregation/base/agent.py
  • tensorrt_llm/_torch/disaggregation/base/kv_transfer.py
  • tensorrt_llm/_torch/disaggregation/native/__init__.py
  • tensorrt_llm/_torch/disaggregation/native/messenger.py
  • tensorrt_llm/_torch/disaggregation/native/utils.py
  • tensorrt_llm/_torch/disaggregation/nixl/__init__.py
  • tensorrt_llm/_torch/disaggregation/nixl/agent.py
🧰 Additional context used
📓 Path-based instructions (2)
**/*.py

📄 CodeRabbit inference engine (CODING_GUIDELINES.md)

**/*.py: The code developed for TensorRT-LLM should conform to Python 3.8+
Indent Python code with 4 spaces. Do not use tabs
Always maintain the namespace when importing Python modules, even if only one class or function from a module is used
Python filenames should use snake_case (e.g., some_file.py)
Python classes should use PascalCase (e.g., class SomeClass)
Python functions and methods should use snake_case (e.g., def my_awesome_function():)
Python local variables should use snake_case, with prefix k for variable names that start with a number (e.g., k_99th_percentile)
Python global variables should use upper snake_case with prefix G (e.g., G_MY_GLOBAL)
Python constants should use upper snake_case (e.g., MY_CONSTANT)
Avoid shadowing variables declared in an outer scope in Python
Initialize all externally visible members of a Python class in the constructor
For Python interfaces that may be used outside a file, prefer docstrings over comments
Use comments in Python for code within a function, or interfaces that are local to a file
Use Google-style docstrings for Python classes and functions, which can be parsed by Sphinx
Python attributes and variables can be documented inline with the format """<type>: Description"""
Avoid using reflection in Python when functionality can be easily achieved without reflection
When using try-except blocks in Python, limit the except clause to the smallest set of errors possible
When using try-except blocks in Python to handle multiple possible variable types (duck-typing), keep the body of the try as small as possible and use the else block for the main logic

Files:

  • tensorrt_llm/_torch/disaggregation/native/utils.py
  • tensorrt_llm/_torch/disaggregation/base/kv_transfer.py
  • tensorrt_llm/_torch/disaggregation/nixl/agent.py
  • tensorrt_llm/_torch/disaggregation/native/messenger.py
  • tensorrt_llm/_torch/disaggregation/base/agent.py
**/*.{cpp,cc,cxx,h,hpp,hxx,cu,cuh,py}

📄 CodeRabbit inference engine (CODING_GUIDELINES.md)

All TensorRT-LLM source files (.cpp, .h, .cu, .py, and other source files) should contain an NVIDIA copyright header with the year of latest meaningful modification

Files:

  • tensorrt_llm/_torch/disaggregation/native/utils.py
  • tensorrt_llm/_torch/disaggregation/base/kv_transfer.py
  • tensorrt_llm/_torch/disaggregation/nixl/agent.py
  • tensorrt_llm/_torch/disaggregation/native/messenger.py
  • tensorrt_llm/_torch/disaggregation/base/agent.py
🧬 Code graph analysis (4)
tensorrt_llm/_torch/disaggregation/base/kv_transfer.py (2)
tensorrt_llm/executor/result.py (1)
  • request_id (727-728)
tensorrt_llm/_torch/disaggregation/native/messenger.py (4)
  • send (24-30)
  • send (121-125)
  • receive (42-47)
  • receive (131-132)
tensorrt_llm/_torch/disaggregation/nixl/agent.py (3)
tensorrt_llm/_utils.py (1)
  • nvtx_range (891-910)
tensorrt_llm/_torch/disaggregation/base/agent.py (15)
  • BaseTransferAgent (68-91)
  • RegMemoryDescs (96-98)
  • TransferRequest (54-59)
  • TransferStatus (61-66)
  • MemoryType (35-40)
  • MemoryDescs (49-51)
  • wait (66-66)
  • register_memory (70-70)
  • deregister_memory (73-73)
  • load_remote_agent (76-76)
  • get_local_agent_desc (79-79)
  • invalidate_remote_agent (82-82)
  • check_remote_descs (91-91)
  • notify_sync_message (88-88)
  • submit_transfer_requests (85-85)
cpp/include/tensorrt_llm/executor/transferAgent.h (2)
  • AgentDesc (199-428)
  • TransferState (277-426)
tensorrt_llm/_torch/disaggregation/native/messenger.py (1)
tensorrt_llm/_torch/disaggregation/native/utils.py (1)
  • get_local_ip (1-34)
tensorrt_llm/_torch/disaggregation/base/agent.py (1)
tensorrt_llm/_torch/disaggregation/nixl/agent.py (8)
  • is_completed (50-52)
  • is_completed (182-184)
  • wait (55-57)
  • wait (186-198)
  • register_memory (86-89)
  • register_memory (210-212)
  • check_remote_descs (120-125)
  • check_remote_descs (226-227)
🪛 Ruff (0.14.10)
tensorrt_llm/_torch/disaggregation/native/utils.py

23-24: try-except-pass detected, consider logging the exception

(S110)


23-23: Do not catch blind exception: Exception

(BLE001)

tensorrt_llm/_torch/disaggregation/base/kv_transfer.py

49-49: SenderBase is an abstract base class, but it has no abstract methods or properties

(B024)


52-52: ReceiverBase is an abstract base class, but it has no abstract methods or properties

(B024)


56-56: Unused method argument: sender

(ARG002)


79-79: Unused method argument: receiver

(ARG002)

tensorrt_llm/_torch/disaggregation/nixl/agent.py

22-22: Unused noqa directive (non-enabled: E402)

Remove unused noqa directive

(RUF100)


72-75: Avoid specifying long messages outside the exception class

(TRY003)


173-173: Unused noqa directive (non-enabled: E402)

Remove unused noqa directive

(RUF100)


217-217: Unused method argument: name

(ARG002)

tensorrt_llm/_torch/disaggregation/native/messenger.py

76-76: Avoid specifying long messages outside the exception class

(TRY003)


116-116: Avoid specifying long messages outside the exception class

(TRY003)


123-123: Consider [recipient, *messages] instead of concatenation

Replace with [recipient, *messages]

(RUF005)


136-136: Avoid specifying long messages outside the exception class

(TRY003)


156-156: Do not catch blind exception: Exception

(BLE001)

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (1)
  • GitHub Check: Pre-commit Check

Comment on lines 66 to 71
@abstractmethod
def send(self, slice: KVSlice) -> TaskIdType: ...

"""
Async send slice to the peer. return the task id. Task state can be polled by poll_task().
"""
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⚠️ Potential issue | 🟡 Minor

Misplaced docstring appears after method definition.

The docstring at lines 69-71 appears after the send method signature instead of inside it, making it a standalone string expression with no effect. Move it inside the method body.

Proposed fix
     @abstractmethod
-    def send(self, slice: KVSlice) -> TaskIdType: ...
-
-    """
-    Async send slice to the peer. return the task id. Task state can be polled by poll_task().
-    """
+    def send(self, slice: KVSlice) -> TaskIdType:
+        """Async send slice to the peer. Return the task id. Task state can be polled by poll_task()."""
+        ...
🤖 Prompt for AI Agents
In @tensorrt_llm/_torch/disaggregation/base/kv_transfer.py around lines 66 - 71,
The docstring currently sits after the abstract method signature for send (def
send(self, slice: KVSlice) -> TaskIdType) and is therefore a no-op; move the
triple-quoted string into the send method body as its proper docstring (directly
under the signature) so the abstractmethod has an explanatory docstring
describing the async send behavior and that the returned TaskIdType can be
polled via poll_task(); remove the standalone string expression left after the
method signature and ensure the method still respects @abstractmethod (body can
be the docstring alone or followed by raise NotImplementedError).

Comment on lines 89 to 94
@abstractmethod
def receive(self, slice: KVSlice) -> TaskIdType: ...

"""
Async receive slice from the peer. return the task id. Task state can be polled by poll_task().
"""
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⚠️ Potential issue | 🟡 Minor

Misplaced docstring appears after method definition.

Same issue as above - the docstring at lines 92-94 is not attached to the receive method.

Proposed fix
     @abstractmethod
-    def receive(self, slice: KVSlice) -> TaskIdType: ...
-
-    """
-    Async receive slice from the peer. return the task id. Task state can be polled by poll_task().
-    """
+    def receive(self, slice: KVSlice) -> TaskIdType:
+        """Async receive slice from the peer. Return the task id. Task state can be polled by poll_task()."""
+        ...
🤖 Prompt for AI Agents
In @tensorrt_llm/_torch/disaggregation/base/kv_transfer.py around lines 89 - 94,
The docstring for the abstract method receive is misplaced after the method
body; move the triple-quoted docstring so it immediately follows the
receive(self, slice: KVSlice) -> TaskIdType: signature (so it becomes the
method's docstring), ensure it uses proper triple quotes and references behavior
(async receive slice from the peer, returns TaskIdType, task state polled via
poll_task()), and keep the @abstractmethod decorator and signature intact.

Comment on lines 96 to 104
if endpoint:
if mode in ["ROUTER", "REP"]:
self._socket.bind(endpoint)
self._endpoint = self._socket.getsockopt_string(zmq.LAST_ENDPOINT)
elif mode in ["DEALER", "REQ"]:
self._socket.connect(endpoint)
self._endpoint = endpoint

logger.debug(f"Initializing ZMQMessenger, mode={mode}, endpoint={self._endpoint}")
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⚠️ Potential issue | 🔴 Critical

self._endpoint may be uninitialized if endpoint is falsy.

If endpoint is None or empty, the if endpoint: block is skipped and self._endpoint is never assigned, leading to an AttributeError at line 104 and in the endpoint property.

Initialize `_endpoint` before the conditional
         self._control_socket.bind(inproc_endpoint)
         self._internal_socket.connect(inproc_endpoint)

+        self._endpoint = None
         if endpoint:
             if mode in ["ROUTER", "REP"]:
                 self._socket.bind(endpoint)
                 self._endpoint = self._socket.getsockopt_string(zmq.LAST_ENDPOINT)
             elif mode in ["DEALER", "REQ"]:
                 self._socket.connect(endpoint)
                 self._endpoint = endpoint
+        else:
+            raise ValueError("endpoint must be provided")

-        logger.debug(f"Initializing ZMQMessenger, mode={mode}, endpoint={self._endpoint}")
+        if self._endpoint:
+            logger.debug(f"Initializing ZMQMessenger, mode={mode}, endpoint={self._endpoint}")
🤖 Prompt for AI Agents
In @tensorrt_llm/_torch/disaggregation/native/messenger.py around lines 96 -
104, The ZMQMessenger constructor can leave self._endpoint uninitialized when
endpoint is falsy, causing AttributeError later (e.g., in the endpoint
property); initialize self._endpoint to a default (None or empty string) before
the conditional that checks endpoint, then preserve the existing logic that sets
self._endpoint inside the if/elif branches for "ROUTER"/"REP" and "DEALER"/"REQ"
so the attribute is always defined whether or not an endpoint was provided.

Comment on lines 217 to 218
def load_remote_agent(self, name: str, agent_desc: bytes):
self.agent.add_remote_agent(agent_desc)
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⚠️ Potential issue | 🟡 Minor

🧩 Analysis chain

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# First, let's look at the file and the method in context
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Repository: NVIDIA/TensorRT-LLM

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Repository: NVIDIA/TensorRT-LLM

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# Check if this class inherits from a base class and if there's an interface definition
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Length of output: 1677


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Pass the name parameter to the nixl library's agent method or document its omission.

The name parameter is declared but unused. The base class interface requires this parameter, and the C++ bindings implementation (BindingsNixlTransferAgent) passes it to load_remote_agent. For consistency, either pass name to add_remote_agent if supported by the Python nixl library, or document why it is not needed.

🧰 Tools
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217-217: Unused method argument: name

(ARG002)

🤖 Prompt for AI Agents
In @tensorrt_llm/_torch/disaggregation/nixl/agent.py around lines 217 - 218, The
load_remote_agent method currently accepts a name parameter but never uses it;
update load_remote_agent to forward name to the nixl library call (call
add_remote_agent with both name and agent_desc) if the Python nixl binding
supports a name argument, mirroring BindingsNixlTransferAgent, or if the binding
does not accept a name then add a short comment/docstring in load_remote_agent
explaining why name is intentionally ignored and that the C++ binding handles
naming instead.

Comment on lines 246 to 249
)
status = self.agent.transfer(handle)
assert status != "ERROR"
return NixlTransferStatus(self.agent, handle)
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⚠️ Potential issue | 🟠 Major

Avoid assert for runtime error handling in production code.

The assert statement can be disabled with -O flag. Use an explicit exception for error handling that should always be checked.

Proposed fix
             handle = self.agent.initialize_xfer(
                 request.op,
                 src_xfer_descs,
                 dst_xfer_descs,
                 request.remote_name,
                 request.sync_message,
             )
             status = self.agent.transfer(handle)
-            assert status != "ERROR"
+            if status == "ERROR":
+                raise RuntimeError(f"Transfer initialization failed for request to {request.remote_name}")
             return NixlTransferStatus(self.agent, handle)
🤖 Prompt for AI Agents
In @tensorrt_llm/_torch/disaggregation/nixl/agent.py around lines 246 - 249, The
code uses assert to check transfer result in the block that calls
self.agent.transfer(handle); replace the assert with explicit runtime error
handling: inspect the returned status from self.agent.transfer(handle) and if it
equals "ERROR" raise a descriptive exception (e.g., RuntimeError or a custom
TransferError) including context such as the handle and/or status; otherwise
return NixlTransferStatus(self.agent, handle). Ensure this change is applied
where status = self.agent.transfer(handle) is used (in the method that returns
NixlTransferStatus).

assert status != "ERROR"
return NixlTransferStatus(self.agent, handle)

except ImportError:
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It's better to move the try-catch for import block into init.py

def _convert_memory_type(self, py_type: str) -> "MemoryType":
"""Convert Python memory type string to C++ MemoryType."""
type_map = {
"DRAM": MemoryType.DRAM,
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class MemoryType(enum):
  ... 

then MemoryType[py_type] should suffice.

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Can we have unit tests for all new classes?

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OK. I will mark this PR as draft status and add tests. Thanks

@Shixiaowei02 Shixiaowei02 marked this pull request as draft January 8, 2026 06:19
@Shixiaowei02 Shixiaowei02 force-pushed the user/xiaoweis/python_kv_transfer_old_flow branch from 1dd0387 to 4b8c619 Compare January 8, 2026 10:26
Signed-off-by: Shixiaowei02 <[email protected]>
@Shixiaowei02 Shixiaowei02 force-pushed the user/xiaoweis/python_kv_transfer_old_flow branch from 4b8c619 to cd618b9 Compare January 8, 2026 10:35
Signed-off-by: Shixiaowei02 <[email protected]>
@Shixiaowei02 Shixiaowei02 added the Disaggregated serving <NV>Deploying with separated, distributed components (params, kv-cache, compute). Arch & perf. label Jan 8, 2026
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