fix(ext-workflow): honor DAPR_GRPC_MAX_INBOUND_MESSAGE_SIZE_BYTES on workflow channels by tezizzm · Pull Request #1085 · dapr/python-sdk

tezizzm · 2026-06-10T01:09:07Z

Description

Long-running workflows whose activity results exceed gRPC's 4 MiB default fail with
RESOURCE_EXHAUSTED: Sent message larger than max (X vs. 4194304). #1024 added
DAPR_GRPC_MAX_INBOUND_MESSAGE_SIZE_BYTES and threaded it through the Dapr API
channel only — it did not cover the workflow (durabletask) channel, so even with
the env var exported, workflows still hit the 4 MiB ceiling once the orchestration
history (input + accumulated activity results) crossed the limit.

This PR mirrors the #1024 pattern in dapr-ext-workflow:

Adds a get_grpc_channel_options() helper in dapr/ext/workflow/util.py. Resolution
order: explicit max_grpc_message_length kwarg → settings.DAPR_GRPC_MAX_INBOUND_MESSAGE_SIZE_BYTES
→ None (gRPC default).
Threads a new optional max_grpc_message_length: Optional[int] = None kwarg through
the three workflow gRPC constructors and passes the resolved channel_options:
- WorkflowRuntime.__init__ → TaskHubGrpcWorker
- DaprWorkflowClient.__init__ (sync) → TaskHubGrpcClient
- aio.DaprWorkflowClient.__init__ (async) → AsyncTaskHubGrpcClient
Updates the public docstrings of all three constructors to document the kwarg and its
precedence.

Unlike #1024, the limit is applied symmetrically to both send and receive, because
workflow activity payloads cross the channel in both directions (worker → daprd carries
activity output too); #1024 only set the receive limit in its env-var branch.

No new environment variable is introduced (reuses #1024's), and no vendored
_durabletask/ internals or dapr/proto/ files are touched.

Issue reference

We strive to have all PR being opened based on an issue, where the problem or feature have been discussed prior to implementation.

Please reference the issue this PR will close: #1084

Checklist

Please make sure you've completed the relevant tasks for this PR, out of the following list:

Code compiles correctly
Created/updated tests
Extended the documentation

…workflow channels Workflow activity payloads over gRPC's 4 MiB default raised RESOURCE_EXHAUSTED because the durabletask channel ignored the message size limit. dapr#1024 plumbed DAPR_GRPC_MAX_INBOUND_MESSAGE_SIZE_BYTES through the Dapr API channel only; the workflow worker and clients still fell back to the gRPC default. Add a get_grpc_channel_options helper that resolves the limit from an explicit max_grpc_message_length kwarg, then the env var, then None, and thread it through WorkflowRuntime, DaprWorkflowClient, and the async DaprWorkflowClient. Unlike dapr#1024, set both send and receive limits symmetrically since workflow payloads cross the channel in both directions. Reuses the existing setting; no new env var. Signed-off-by: Martez Killens <5050479+tezizzm@users.noreply.github.com>

codecov · 2026-06-10T08:26:32Z

Codecov Report

❌ Patch coverage is 99.08257% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 82.79%. Comparing base (bffb749) to head (9f40992).
⚠️ Report is 142 commits behind head on main.

Files with missing lines	Patch %	Lines
...t/dapr-ext-workflow/tests/test_workflow_runtime.py	96.42%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1085      +/-   ##
==========================================
- Coverage   86.63%   82.79%   -3.85%     
==========================================
  Files          84      146      +62     
  Lines        4473    14945   +10472     
==========================================
+ Hits         3875    12373    +8498     
- Misses        598     2572    +1974

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

Copilot

Pull request overview

This PR fixes workflow gRPC message-size handling in dapr-ext-workflow so long-running workflows with large activity payloads (or large accumulated orchestration history) can honor DAPR_GRPC_MAX_INBOUND_MESSAGE_SIZE_BYTES (and an explicit max_grpc_message_length kwarg) instead of failing at gRPC’s default 4 MiB limit.

Changes:

Added get_grpc_channel_options() utility to resolve workflow gRPC channel options (kwarg → env var → gRPC default), applying limits symmetrically for send/receive.
Threaded max_grpc_message_length: Optional[int] = None through workflow runtime and both sync/async workflow clients, passing resolved channel_options into durabletask constructors.
Added unit tests covering precedence and symmetric option application for runtime and clients.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
ext/dapr-ext-workflow/dapr/ext/workflow/util.py	Adds `get_grpc_channel_options()` to compute workflow-channel gRPC max message size options.
ext/dapr-ext-workflow/dapr/ext/workflow/workflow_runtime.py	Threads `max_grpc_message_length` into `WorkflowRuntime` and passes computed `channel_options` to `TaskHubGrpcWorker`.
ext/dapr-ext-workflow/dapr/ext/workflow/dapr_workflow_client.py	Threads `max_grpc_message_length` into sync `DaprWorkflowClient` and passes computed `channel_options` to `TaskHubGrpcClient`.
ext/dapr-ext-workflow/dapr/ext/workflow/aio/dapr_workflow_client.py	Threads `max_grpc_message_length` into async `DaprWorkflowClient` and passes computed `channel_options` to `AsyncTaskHubGrpcClient`.
ext/dapr-ext-workflow/tests/test_workflow_util.py	Adds tests for `get_grpc_channel_options()` precedence and symmetric send/receive options.
ext/dapr-ext-workflow/tests/test_workflow_runtime.py	Adds tests asserting `WorkflowRuntime` passes symmetric `channel_options` derived from kwarg/env var.
ext/dapr-ext-workflow/tests/test_workflow_client.py	Adds tests asserting sync `DaprWorkflowClient` passes symmetric `channel_options` derived from kwarg/env var.
ext/dapr-ext-workflow/tests/test_workflow_client_aio.py	Adds tests asserting async `DaprWorkflowClient` passes symmetric `channel_options` derived from kwarg/env var.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

CasperGN · 2026-06-10T09:17:15Z

+    Args:
+        max_grpc_message_length: Explicit max gRPC message size in bytes. Takes
+            precedence over the env-var setting when truthy.
+
+    Returns:
+        A sequence of ``(option, value)`` tuples setting both send and receive
+        limits, or ``None`` when no limit is configured.
+    """
+    size = max_grpc_message_length or settings.DAPR_GRPC_MAX_INBOUND_MESSAGE_SIZE_BYTES or None
+    if size is None:
+        return None


I don't agree with this suggestion.

CasperGN · 2026-06-10T09:17:48Z

+    size = max_grpc_message_length or settings.DAPR_GRPC_MAX_INBOUND_MESSAGE_SIZE_BYTES or None
+    if size is None:
+        return None
+    return [
+        ('grpc.max_send_message_length', size),
+        ('grpc.max_receive_message_length', size),
+    ]


Suggested change

size = max_grpc_message_length or settings.DAPR_GRPC_MAX_INBOUND_MESSAGE_SIZE_BYTES or None

if size is None:

return None

return [

('grpc.max_send_message_length', size),

('grpc.max_receive_message_length', size),

]

size = max_grpc_message_length or settings.DAPR_GRPC_MAX_INBOUND_MESSAGE_SIZE_BYTES

if not size:

return None

return [

('grpc.max_send_message_length', size),

('grpc.max_receive_message_length', size),

]

This allows None & 0 to fall through and return None for both

tezizzm requested review from a team as code owners June 10, 2026 01:09

CasperGN requested a review from Copilot June 10, 2026 08:31

Copilot started reviewing on behalf of CasperGN June 10, 2026 08:31 View session

Copilot AI reviewed Jun 10, 2026

View reviewed changes

CasperGN requested changes Jun 10, 2026

View reviewed changes

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

fix(ext-workflow): honor DAPR_GRPC_MAX_INBOUND_MESSAGE_SIZE_BYTES on workflow channels#1085

fix(ext-workflow): honor DAPR_GRPC_MAX_INBOUND_MESSAGE_SIZE_BYTES on workflow channels#1085
tezizzm wants to merge 1 commit into
dapr:mainfrom
tezizzm:fix/workflow-grpc-max-message-size

tezizzm commented Jun 10, 2026

Uh oh!

codecov Bot commented Jun 10, 2026

Uh oh!

Copilot AI left a comment

Uh oh!

CasperGN Jun 10, 2026

Uh oh!

CasperGN Jun 10, 2026

Uh oh!

CasperGN Jun 10, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Conversation

tezizzm commented Jun 10, 2026

Description

Issue reference

Checklist

Uh oh!

codecov Bot commented Jun 10, 2026

Codecov Report

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

CasperGN Jun 10, 2026

Choose a reason for hiding this comment

Uh oh!

CasperGN Jun 10, 2026

Choose a reason for hiding this comment

Uh oh!

CasperGN Jun 10, 2026

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants