Fix: Make memory_service optional in CLI to match Runner implementation (Issue #3251)

[totsukash]

Summary

• Make memory_service default to None in CLI when --memory_service_uri is not specified
• Align CLI behavior with Runner class implementation where memory_service is optional
• Prevent unnecessary memory accumulation and potential OOM issues in long-running production environments

Problem Statement

When running adk api_server without the --memory_service_uri flag, the CLI automatically creates an InMemoryMemoryService instance by default. This behavior is inconsistent with the Runner class implementation, where memory service can be None, and can lead to memory accumulation and potential Out Of Memory (OOM) errors in production environments.

Changes

Modified file: src/google/adk/cli/fast_api.py (line 98-101)

Before:

else:
    memory_service = InMemoryMemoryService()

After:

else:
    # Set to None to match Runner implementation where memory_service is optional.
    # This prevents unnecessary memory accumulation and potential OOM issues.
    # See: https://github.com/google/adk-python/issues/3251
    memory_service = None

Testing Plan

Unit Tests

Added three comprehensive unit tests in tests/unittests/cli/test_fast_api.py:

• ✅ test_memory_service_none_when_no_uri_provided: Verifies that memory_service is None when no URI is provided
• ✅ test_memory_service_created_when_uri_provided: Verifies that memory_service is created correctly when URI is provided
• ✅ test_invalid_memory_service_uri_raises_exception: Verifies proper exception handling for invalid URIs

Manual E2E Testing (To be performed)

1. Scenario 1: Start server without --memory_service_uri flag

   adk api_server test_agent --port 8000

   • Expected: Server starts successfully without creating InMemoryMemoryService

2. Scenario 2: Start server with explicit --memory_service_uri

   adk api_server test_agent --port 8000 --memory_service_uri "memory://in_memory"

   • Expected: Server starts with memory service properly initialized

3. Scenario 3: Verify compatibility with other services

   adk api_server test_agent --port 8000 \
     --session_service_uri "sqlite:///test.db" \
     --artifact_service_uri "file://./artifacts"

   • Expected: All services work correctly together with memory_service=None

Impact

• Consistency: Aligns CLI behavior with Runner class implementation
• Memory Efficiency: Prevents unnecessary memory allocation for unused features
• OOM Risk Mitigation: Reduces risk of memory leaks in long-running production deployments
• Backward Compatibility: ✅ Maintained - all code already handles Optional[BaseMemoryService]

Related Issue

Fixes #3251

Checklist

• Code changes implemented
• Unit tests added
• Comments added explaining the change
• Issue reference included
• Manual E2E testing (to be performed by reviewer)
• CI/CD tests pass

---

🤖 Generated with Claude Code

Co-Authored-By: Claude [email protected]

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[gemini-code-assist]

Summary of Changes

Hello @totsukash, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses an inconsistency in the adk api_server CLI, where a memory service was implicitly instantiated even when not explicitly requested. By making the memory_service optional and defaulting to None when no URI is specified, the change harmonizes the CLI's behavior with the Runner class. This enhancement significantly improves memory efficiency by preventing unnecessary resource allocation and reduces the risk of Out Of Memory errors in production systems, ensuring a more robust and consistent application experience.

Highlights

• CLI memory_service behavior: The adk api_server command now defaults memory_service to None when the --memory_service_uri flag is not provided, instead of automatically creating an InMemoryMemoryService.
• Consistency and Memory Efficiency: This change aligns the CLI's behavior with the Runner class implementation, where the memory service is optional, preventing unnecessary memory accumulation and mitigating potential Out Of Memory (OOM) issues in long-running production environments.
• Unit Test Coverage: Three new unit tests have been added to tests/unittests/cli/test_fast_api.py to thoroughly verify that memory_service is correctly set to None when no URI is provided, created when a valid URI is given, and that an exception is raised for invalid URIs.

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[adk-bot]

Response from ADK Triaging Agent

Hello @totsukash, thank you for your contribution!

Before we can proceed with the review, could you please sign the Contributor License Agreement (CLA)? The CLA check is currently failing. For details, please see the comment from the google-cla bot.

Thanks!

[gemini-code-assist]

Code Review

This pull request addresses issue #3251 by making the memory_service optional in the CLI, aligning its behavior with the Runner class implementation. This change prevents unnecessary memory accumulation and potential OOM issues in long-running production environments. The changes include modifying src/google/adk/cli/fast_api.py to set memory_service to None by default and adding unit tests in tests/unittests/cli/test_fast_api.py to verify the new behavior. The code changes look good and the tests are comprehensive.

[DeanChensj]

Close as the original issue was a false alarm.