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feat(bigtable): raise the UDS channel inbound message cap to 256 MB #18782

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feat(bigtable): raise the UDS channel inbound message cap to 256 MB #18782

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14 changes: 13 additions & 1 deletion packages/google-cloud-bigtable/google/cloud/bigtable/data/_async/_accelerator_client.py
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Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,16 @@
_MUTATE_ROW_METHOD = "/google.bigtable.v2.Bigtable/MutateRow"
_READ_ROWS_METHOD = "/google.bigtable.v2.Bigtable/ReadRows"

# Inbound message cap on the UDS channel. gRPC defaults this to 4 MiB, a limit
# meant for a channel that crosses a network. This one doesn't leave the
# machine: the daemon has already paid the cost of pulling the response off the
# wire, and all the cap does on this hop is turn an otherwise-fine read into
# RESOURCE_EXHAUSTED. Raise it well past anything the service itself produces so
# the UDS leg is never the narrower of the two.
_MAX_RECEIVE_MESSAGE_LENGTH = 256 * 1024 * 1024

_CHANNEL_OPTIONS = (("grpc.max_receive_message_length", _MAX_RECEIVE_MESSAGE_LENGTH),)

@sushanb sushanb Oct 22, 2026

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Two concerns with the one-sided cap:

1. Send-side left at the gRPC 4 MiB default — silent regression vs. the native path. The native google-cloud-bigtable Python client sets both grpc.max_send_message_length and grpc.max_receive_message_length to -1 (unlimited). This PR raises only inbound, so an ApplyBulk / MutateRow with a payload >4 MiB (allowed by the server's 100 MiB per-cell limit) will fail at the accelerator channel's outbound serialization check with no analogous server-side error. On the native path the same call goes through. Suggest raising send too:

Suggested change
_CHANNEL_OPTIONS = (("grpc.max_receive_message_length", _MAX_RECEIVE_MESSAGE_LENGTH),)
_CHANNEL_OPTIONS = (
("grpc.max_receive_message_length", _MAX_RECEIVE_MESSAGE_LENGTH),
("grpc.max_send_message_length", _MAX_RECEIVE_MESSAGE_LENGTH),
)

2. Pick a side on the 256 MB number. Native uses -1 (unlimited). 256 MB from thin air invites "why not 128? why not 1 GiB?" and future drift when the native client bumps. Either match native (-1, both directions) and document "match native" in the comment, or if 256 MB is a deliberate memory-safety choice at the UDS hop, say that explicitly.



@CrossSync.convert_class(sync_name="_AcceleratorClient")
class _AsyncAcceleratorClient:
Expand All @@ -59,7 +69,9 @@ class _AsyncAcceleratorClient:
def __init__(self, uds_path: str, auth_secret: str):
self._uds_path = uds_path
self._metadata = (("x-accelerator-token", auth_secret),)
self._channel = insecure_channel(_uds_target(uds_path))
self._channel = insecure_channel(
_uds_target(uds_path), options=_CHANNEL_OPTIONS

@sushanb sushanb Oct 22, 2026

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Nit: no test exercises _CHANNEL_OPTIONS. Even a one-liner asserting the option tuple is on self._channel's options would pin both the key spelling (grpc.max_receive_message_length is easy to typo) and the value. Low priority.

)
self._mutate_row_stub = self._channel.unary_unary(
_MUTATE_ROW_METHOD,
request_serializer=MutateRowRequest.serialize,
Expand Down
6 changes: 5 additions & 1 deletion ...ges/google-cloud-bigtable/google/cloud/bigtable/data/_sync_autogen/_accelerator_client.py
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Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,8 @@

_MUTATE_ROW_METHOD = "/google.bigtable.v2.Bigtable/MutateRow"
_READ_ROWS_METHOD = "/google.bigtable.v2.Bigtable/ReadRows"
_MAX_RECEIVE_MESSAGE_LENGTH = 256 * 1024 * 1024
_CHANNEL_OPTIONS = (("grpc.max_receive_message_length", _MAX_RECEIVE_MESSAGE_LENGTH),)


class _AcceleratorClient:
Expand All @@ -55,7 +57,9 @@ class _AcceleratorClient:
def __init__(self, uds_path: str, auth_secret: str):
self._uds_path = uds_path
self._metadata = (("x-accelerator-token", auth_secret),)
self._channel = insecure_channel(_uds_target(uds_path))
self._channel = insecure_channel(
_uds_target(uds_path), options=_CHANNEL_OPTIONS
)
self._mutate_row_stub = self._channel.unary_unary(
_MUTATE_ROW_METHOD,
request_serializer=MutateRowRequest.serialize,
Expand Down
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