fix: refine reconnect strategy in azure asr extension

[sunxilin]

[claude]

Pull Request Review: Refine Reconnect Strategy in Azure ASR Extension

Summary

This PR transitions the Azure ASR extension from a fixed 5-attempt retry limit to an unlimited reconnection strategy with exponential backoff capped at 2.4 seconds. This is a significant architectural change that improves resilience for transient network issues.

---

Code Quality & Best Practices

✅ Strengths

1. Good Documentation: The docstrings in reconnect_manager.py:8-16 clearly explain the new unlimited retry behavior and max delay cap.

2. Clean Simplification: Removing the max_attempts parameter and can_retry() method reduces complexity and makes the code easier to understand.

3. Comprehensive Test Coverage: The new test test_unlimited_reconnect.py validates reconnection beyond the old 5-attempt limit with a thorough test (8 failures before success).

4. Proper Error Messaging: Error messages now correctly indicate retries will continue (e.g., "Will retry..." in reconnect_manager.py:96).

5. Version Bump: Correctly incremented version to 0.2.3 in manifest.json:4.

---

Potential Issues & Concerns

⚠️ Critical: Infinite Retry Loop Risk

Location: extension.py:514-540, reconnect_manager.py:51-109

Issue: The unlimited retry strategy could lead to infinite loops in certain failure scenarios:

1. Invalid credentials: If the Azure API key or region is permanently invalid, the extension will retry forever, consuming resources unnecessarily.
2. Service permanently down: If Azure's service is down for an extended period, there's no circuit breaker.
3. Resource exhaustion: In production with multiple extensions, unlimited retries could accumulate and exhaust memory/CPU.

Recommendation: Consider implementing one of these safeguards:

• Max retry time window (e.g., stop after 30 minutes of continuous failures)
• Circuit breaker pattern (stop after N consecutive failures within X seconds, then allow periodic retry)
• Configuration option to set max attempts for production deployments
• Exponential backoff cap increase (e.g., increase max delay to 30s or 60s after prolonged failures)

Example addition to ReconnectManager:

def __init__(
    self,
    base_delay: float = 0.3,
    max_delay: float = 2.4,
    max_retry_duration: Optional[float] = None,  # e.g., 1800 seconds = 30 min
    logger=None,
):
    # ... existing code ...
    self.max_retry_duration = max_retry_duration
    self.first_failure_time: Optional[float] = None

async def handle_reconnect(...):
    if self.first_failure_time is None:
        self.first_failure_time = time.time()
    elif self.max_retry_duration and (time.time() - self.first_failure_time) > self.max_retry_duration:
        # Stop retrying after max duration
        if error_handler:
            await error_handler(ModuleError(...))
        return False
    # ... existing retry logic ...

⚠️ Issue: Error Code Semantics

Location: reconnect_manager.py:104

code=ModuleErrorCode.FATAL_ERROR.value,
message=f"Reconnection attempt #{self.attempts} failed: {str(e)}",

Issue: Each failed reconnection attempt sends a FATAL_ERROR, but the extension continues retrying. The term "FATAL" typically implies an unrecoverable error that stops execution. This creates confusion:

• Users/monitoring systems might interpret FATAL_ERROR as requiring intervention
• Error count metrics could be misleading (many FATAL_ERRORs but service still works)

Recommendation:

• Use NON_FATAL_ERROR for individual retry failures (consistent with the canceled handler at extension.py:432)
• Only send FATAL_ERROR if you implement a max retry duration and actually give up

⚠️ Issue: Test Changes to test_invalid_params.py

Location: test_invalid_params.py:64-68

Before:

property_json = {"params": {}}

After:

property_json = {
    "params": {
        "key": "",
    }
}

Issue: This change alters what the test validates:

• Before: Testing completely missing params (empty dict)
• After: Testing empty key value

Questions:

1. Was the original test insufficient? If so, consider keeping both test cases.
2. Does the extension properly validate empty vs. missing keys? Looking at config.py:9, key: str = "" has a default, so an empty string is technically valid from Pydantic's perspective, but will fail with Azure SDK.

Recommendation:

• Add a docstring explaining what failure mode this test validates
• Consider separate tests for: (1) missing key, (2) empty key, (3) missing region

ℹ️ Minor: Unused Instance Variable

Location: test_unlimited_reconnect.py:29

self.reconnect_delays = []

This list is initialized but never populated or used. Consider removing it or implementing delay tracking for validation.

---

Performance Considerations

✅ Good: Capped Exponential Backoff

The max delay cap of 2.4 seconds (reconnect_manager.py:73) is well-chosen:

• Prevents overwhelming Azure's API with rapid retry attempts
• Balances between responsiveness and resource usage
• Follows best practices for retry strategies

⚠️ Consideration: Background Task Accumulation

Location: extension.py:417

Each session_stopped event triggers _handle_reconnect(). If the connection fails immediately and repeatedly:

1. Multiple reconnection coroutines could be spawned simultaneously
2. Each adds exponential backoff delays but consumes a task slot

Recommendation: Add a flag to prevent concurrent reconnection attempts:

self.reconnecting = False  # Add to __init__

async def _handle_reconnect(self):
    if self.reconnecting:
        self.ten_env.log_debug("Reconnection already in progress")
        return
    
    self.reconnecting = True
    try:
        # ... existing reconnection logic ...
    finally:
        self.reconnecting = False

---

Security Concerns

✅ No Security Issues Identified

The changes don't introduce security vulnerabilities:

• API keys continue to be handled securely with encryption for logging
• No new external dependencies
• No changes to authentication logic

---

Test Coverage

✅ Excellent Test Addition

The new test test_unlimited_reconnect.py is well-designed:

• Tests the core behavior (8 failures exceed old limit of 5)
• Uses proper mocking with SimpleNamespace and threading timers
• Validates error count matches failure count
• Has clear docstrings

📝 Suggestions for Additional Tests

Consider adding tests for:

1. Backoff delay verification: Assert that delays follow exponential pattern and cap at 2.4s
2. Error handler invocation: Verify error handler is called correctly for each failure
3. Connection success after 1st failure: Test quick recovery (1 failure then success)
4. Very long failure sequence: Test 20+ failures to ensure no resource leaks or stack issues

---

Documentation

✅ Good

• Docstrings updated to reflect unlimited retries
• Comments updated in extension.py:53

📝 Suggestions

1. Add a migration note explaining the behavior change from 0.2.2 to 0.2.3
2. Document recommended monitoring/alerting for reconnection attempts
3. Consider adding configuration guidance for production deployments

---

Overall Assessment

Quality: Good refactoring with clear intent and proper testing

Risk Level: Medium-High due to potential infinite retry loops

Recommendation:

1. Must address: Implement safeguards against infinite retry loops (max time window or circuit breaker)
2. Should address: Change error code from FATAL_ERROR to NON_FATAL_ERROR for retries
3. Should address: Add reconnection concurrency guard
4. Consider: Enhance test coverage for edge cases

The core concept is sound, but production resilience would be significantly improved with the suggested safeguards.

---

Files Reviewed:

• reconnect_manager.py ✅
• extension.py ✅
• test_unlimited_reconnect.py ✅
• test_invalid_params.py ⚠️
• manifest.json ✅
• test_multi_language.py ✅ (minor audio file change)

[claude]

Pull Request Review: Refine Reconnect Strategy in Azure ASR Extension

Summary

This PR removes the 5-attempt limit for reconnection retries in the Azure ASR extension, implementing an unlimited retry strategy with exponential backoff capped at 2.4 seconds. The changes are well-structured with good test coverage.

---

✅ Strengths

1. Clear Intent and Good Motivation

• Removing the arbitrary retry limit makes sense for production ASR systems where transient network issues should not cause permanent failures
• The exponential backoff with a maximum cap (2.4s) prevents overwhelming the service provider

2. Well-Structured Code Changes

• Clean removal of max_attempts parameter and can_retry() method
• Appropriate renaming: reset_counter() → _reset_counter() (private method)
• Consistent documentation updates across all affected files

3. Excellent Test Coverage

• New test test_unlimited_reconnect.py validates behavior beyond the old 5-attempt limit (tests 8 failures)
• Test follows existing patterns from test_reconnect.py
• Proper verification that errors are still reported for each failed attempt

---

🔍 Issues & Concerns

CRITICAL: Potential Infinite Loop Risk

Location: reconnect_manager.py:51-111 and extension.py:514-540

Issue: The current implementation has no mechanism to stop retrying. If Azure ASR is permanently unavailable (service outage, invalid credentials, etc.), the extension will retry indefinitely.

Impact:

• Resource leakage (increasing memory for attempt counter)
• Continued error message spam in logs
• No way to gracefully handle permanent failures
• Users have no indication that something is fundamentally wrong

Recommendations:

1. Add a configurable maximum delay threshold - After reaching a certain total elapsed time (e.g., 5 minutes), escalate the error severity or add longer delays between attempts

2. OR: Add a circuit breaker pattern - After many consecutive failures, temporarily stop retrying and require manual intervention or wait for external health check

3. OR: Make the unlimited retry behavior opt-in - Add a configuration flag in config.py

---

ISSUE: Error Reporting Semantics

Location: reconnect_manager.py:102-109

Problem: Using FATAL_ERROR for transient reconnection failures is semantically incorrect:

• "FATAL" typically implies unrecoverable errors
• These errors are actually transient/recoverable since retries will continue
• Downstream systems may misinterpret this and take drastic actions (alerting, shutting down, etc.)

Recommendation: Use NON_FATAL_ERROR for reconnection attempts

---

MINOR: Test Case Issues

1. Test Configuration Inconsistency

Location: test_invalid_params.py:64-67

Question: Is this change related to the reconnection strategy? The commit message and PR description don't explain this modification. If this is a separate bugfix, it should be documented or split into a separate commit.

2. Integration Test File Reference

Location: test_multi_language.py:306

Question: Why change from the hotwords test file to the standard file? This appears unrelated to reconnection logic.

---

MINOR: Documentation Issues

Location: extension.py:514-521

Issue: The docstring phrase "or max attempts are reached" is now incorrect since there's no maximum.

---

🔒 Security Considerations

✅ No new security issues introduced

• API key handling remains properly encrypted in logs
• No exposure of sensitive data in error messages
• Test fixtures use fake credentials appropriately

---

🎯 Performance Considerations

✅ Performance Impact: Minimal to Positive

Pros:

• Exponential backoff with cap prevents thundering herd
• Will eventually reconnect after transient issues (better availability)

Cons:

• Unbounded retries could theoretically consume resources during prolonged outages
• Error messages will continue indefinitely (log spam)

---

🧪 Test Coverage

✅ Good Test Coverage

Strengths:

• New test validates unlimited retry behavior
• Tests 8 failures (more than old limit of 5)
• Verifies error count matches attempt count

---

📋 Recommendations Summary

Must Fix (Critical):

1. ⚠️ Add safeguards for infinite retry loop - Implement escalation logging, circuit breaker, or configurable limit
2. ⚠️ Fix error code semantics - Use NON_FATAL_ERROR instead of FATAL_ERROR for reconnection attempts

Should Fix (Important):

3. Document or separate unrelated test file changes (test_invalid_params.py, test_multi_language.py)
4. Update docstring in extension.py:514-521 to remove "max attempts" reference

Nice to Have (Minor):

5. Add periodic reconnection statistics logging
6. Add more debugging info to get_attempts_info()

---

🎓 Code Quality Score: B+

Breakdown:

• ✅ Code structure: Excellent
• ✅ Test coverage: Good
• ✅ Documentation: Good (with minor issues)
• ⚠️ Robustness: Needs improvement (infinite loop risk)
• ✅ Style consistency: Excellent

Overall: This is a well-intentioned change with good code quality, but needs safeguards to prevent indefinite retries in production.

---

💬 Questions for Author

1. What is the expected behavior when Azure credentials are invalid or expired? Should it retry forever?
2. How should operators/monitoring systems detect that reconnection is failing persistently?
3. Are the test file changes in test_invalid_params.py and test_multi_language.py related to this PR?
4. Have you tested this behavior in a staging environment with simulated Azure outages?

---

Review completed by: Claude Code (Automated Code Review)
Review date: 2025-12-29

[claude]

Pull Request Review: Refine reconnect strategy in azure asr extension

Summary

This PR removes the reconnection retry limit from the Azure and Tencent ASR extensions, implementing an unlimited retry strategy with exponential backoff. The changes allow the ASR services to continuously attempt reconnection until successful, rather than giving up after 5 attempts.

✅ Strengths

1. Well-Tested Changes

• Excellent test coverage: New test test_unlimited_reconnect.py validates the unlimited retry behavior by simulating 8 consecutive failures (beyond the old 5-attempt limit)
• Test design: The test properly validates both the retry mechanism and error counting
• Realistic simulation: Uses threading timers to simulate async reconnection scenarios

2. Clean API Design

• The removal of can_retry() method simplifies the reconnection logic
• _reset_counter() is now properly private (prefixed with _)
• Good use of exponential backoff with a maximum delay cap (2.4s) to prevent overwhelming the service provider

3. Clear Documentation

• Updated docstrings accurately reflect the new unlimited retry behavior
• Comments in extension.py:53 clearly state "unlimited retries and backoff strategy"

4. Consistent Cross-Extension Changes

• Applied the same pattern to both azure_asr_python (0.2.2 → 0.2.3) and tencent_asr_python (0.2.9 → 0.2.10)
• Tencent implementation uses similar parameters: reconnect_max_retries=0 to indicate infinite reconnection

⚠️ Issues & Concerns

1. CRITICAL: Resource Exhaustion & Denial of Service Risk

Problem: Unlimited retries without a circuit breaker pattern can cause severe issues in reconnect_manager.py:95-111.

Risks:

• Memory leak: The attempts counter will grow indefinitely without bound, eventually causing integer overflow issues
• Log flooding: Continuous error logging can fill disk space and make debugging harder
• Thread exhaustion: Each failed attempt spawns async tasks that may not be properly cleaned up
• Cascading failures: If the service is down for maintenance, all clients will hammer it indefinitely
• No graceful degradation: Users have no way to know if the service is temporarily or permanently unavailable

Recommendation: Add counter overflow protection and warnings after many attempts.

2. Error Classification Missing

The current implementation treats all errors the same way - it always retries, regardless of error type.

Problems:

• Permanent failures (invalid API key, wrong region) will retry forever
• Rate limiting errors should use longer backoff
• Network errors vs authentication errors need different strategies

Recommendation: Classify errors into transient (network issues) vs permanent (invalid credentials) and handle accordingly. Permanent errors should not retry indefinitely.

3. Code Removal Without Migration Path

In extension.py:523-531, the PR removes the can_retry() check without providing a configuration option.

Problem: Users who rely on the retry limit for fail-fast behavior now have no configuration option to limit retries.

Recommendation: Add configuration parameters in manifest.json for reconnect_max_attempts with 0 = unlimited as default.

4. Test Coverage Gaps

While test_unlimited_reconnect.py is excellent, it doesn't cover:

1. Long-running reconnection: What happens after 100+ failures?
2. Memory usage: Does the attempt counter or log buffer grow unbounded?
3. Concurrent reconnection requests: What if multiple _handle_reconnect() calls overlap?

5. Minor: Test File Change Unexplained

In test_multi_language.py:306, the audio file changed from 16k_zh_cn_hotwords.pcm to 16k_zh_cn.pcm. This isn't mentioned in the PR description. Is this intentional?

6. Inconsistent Error Reporting

In reconnect_manager.py:102-109, errors are reported with ModuleErrorCode.FATAL_ERROR, but reconnection continues.

Problem: The error code FATAL_ERROR suggests termination, but the system continues retrying. This creates confusion.

Recommendation: Use ModuleErrorCode.TRANSIENT_ERROR or similar to more accurately represent the situation.

📊 Performance Considerations

Positive

• Exponential backoff with max cap (2.4s) prevents connection storms
• Delay calculation is efficient

Concerns

• Unbounded growth of attempts counter (integer overflow risk after many attempts)
• Continuous error logging could impact disk I/O performance
• No metrics collection for monitoring reconnection health

🔒 Security Considerations

Low Risk

• No credential handling changes
• No new external dependencies
• Test uses mock keys appropriately

Medium Risk

• DoS amplification: If Azure/Tencent services are under attack, unlimited retries from many clients could amplify the problem
• Log injection: Error messages from exceptions are logged without sanitization

💡 Recommendations

Must Address

1. Add circuit breaker logic to detect and respond to prolonged failures
2. Classify errors into permanent vs transient categories
3. Implement counter overflow protection
4. Document the behavior change in a migration guide or release notes

Should Address

1. Add configurable retry limits (with 0 = unlimited as default)
2. Use more appropriate error codes (not FATAL_ERROR for transient failures)
3. Add metrics/telemetry for monitoring reconnection health
4. Explain or revert the test_multi_language.py audio file change

Nice to Have

1. Implement adaptive backoff based on error patterns
2. Add integration tests for long-running reconnection scenarios
3. Provide dashboard/monitoring hooks for reconnection metrics
4. Add jitter to backoff delays to prevent thundering herd

Overall Assessment

Code Quality: 7/10 - Clean implementation with good test coverage, but missing critical safeguards

Risk Level: Medium-High - The unlimited retry approach can cause operational issues without proper guardrails

Recommendation: Request Changes - Address the resource exhaustion and error classification issues before merging. The core idea is sound, but production deployments need better failure handling.

---

Great work on improving the reconnection robustness! The test coverage is excellent. With the suggested safeguards, this will be a solid improvement to the ASR extensions.

[claude]

Code Review: PR #1927 - Refine Reconnect Strategy in Azure ASR Extension

Summary

This PR refactors the Azure ASR extension's reconnection strategy from a limited retry model (5 attempts) to an unlimited retry model with exponential backoff. The changes also align the Tencent ASR extension with similar unlimited reconnection parameters.

Positive Aspects

✅ Well-tested change: The new test validates the unlimited reconnection beyond the old 5-attempt limit with 8 failures before success.

✅ Clear intent: The change addresses a real user pain point where ASR connections would fail permanently after 5 attempts, requiring manual intervention.

✅ Good documentation: Updated docstrings clearly explain the unlimited retry strategy and exponential backoff with capping.

✅ Consistent approach: Both Azure and Tencent ASR extensions now use unlimited reconnection, providing consistent behavior across providers.

Issues and Concerns

Critical: Resource Exhaustion Risk

Location: reconnect_manager.py:51-111

The unlimited retry strategy with no circuit breaker or maximum timeout poses significant risks:

1. Infinite loops: If the service provider has a prolonged outage or credentials are invalid, the extension will retry indefinitely, consuming resources.
2. Memory/thread leaks: Each reconnection attempt may allocate resources (threads, event handlers, connections) that could accumulate if not properly cleaned up.
3. No graceful degradation: There's no mechanism to notify users or the system that reconnection has been attempted many times without success.

Recommendation: Consider one of these approaches:

• Add a maximum total retry duration (e.g., 30 minutes) instead of a maximum attempt count
• Implement a circuit breaker pattern that temporarily stops retry attempts after excessive failures
• Add a configurable parameter to allow users to set retry limits based on their use case
• Add exponential alerting (log WARN/ERROR at increasing intervals: 10th attempt, 50th, 100th, etc.)

Moderate: Error Handling Semantics Changed

Location: extension.py:523-530

The removal of the can_retry() check in _handle_reconnect() means error codes sent via send_asr_error() are now marked as FATAL_ERROR on every attempt, but the extension continues retrying. This is semantically inconsistent.

Recommendation: Change to ModuleErrorCode.NON_FATAL_ERROR.value or create a new error code like RECONNECTION_ATTEMPT_FAILED to better reflect the transient nature.

Moderate: Missing Configuration Validation

Location: test_invalid_params.py:63-68

The test was updated to include a key parameter with an empty string. However, with unlimited retries, an empty/invalid key will cause infinite reconnection attempts. The extension should validate critical configuration parameters (key, region) at initialization and fail fast with a clear error rather than entering an infinite retry loop.

Recommendation: Add validation in on_init() to check for empty/invalid credentials before attempting any connection.

Minor: Inconsistent Max Delay Values

Azure max_delay=2.4s vs Tencent reconnect_max_delay=4s. Consider documenting why different values are appropriate for each provider.

Minor: Test File Name Change

test_multi_language.py:306 - Changed from 16k_zh_cn_hotwords.pcm to 16k_zh_cn.pcm. This appears unrelated to the reconnection changes.

Performance Considerations

1. Exponential backoff cap is good: The 2.4s maximum delay prevents excessive waiting while still being respectful to the service provider.
2. Sleep during reconnection properly yields control, preventing blocking.
3. No backoff reset: Once the max delay (2.4s) is reached, all subsequent attempts will wait 2.4s. Consider implementing jitter to prevent thundering herd issues.

Security Concerns

1. Credential exposure in logs: Ensure that self.config.to_json(sensitive_handling=True) properly redacts the API key.
2. DoS potential: With unlimited retries, a malicious actor who can trigger disconnections could cause excessive API calls to the service provider.

Test Coverage

Good Coverage:

• New test validates reconnection beyond old limit
• Tests error counting to ensure errors are properly reported
• Mock framework properly simulates Azure SDK behavior

Missing Test Cases:

1. No test for max_delay cap
2. No test for very long outages (100+ reconnection attempts)
3. No test for connection cleanup
4. No test for invalid credentials
5. No test for concurrent operations

Code Quality

✅ Clean, readable code with clear comments
✅ Proper use of async/await patterns
✅ Type hints are present and helpful
✅ Follows existing code style and conventions

Recommendations Summary

Before Merge:

1. Add a maximum total retry duration or circuit breaker to prevent infinite loops
2. Change error code from FATAL_ERROR to NON_FATAL_ERROR for retry attempts
3. Add credential validation in on_init() to fail fast on invalid configuration

Post-Merge (Nice to Have):

1. Add monitoring/alerting for excessive reconnection attempts
2. Add test coverage for edge cases and long-running failures
3. Document the different max_delay values for Azure vs Tencent
4. Consider adding backoff jitter to prevent thundering herd

Overall Assessment

This is a good improvement that addresses a real operational issue. The code quality is high and the testing demonstrates the feature works as intended. However, the unlimited retry strategy needs safeguards to prevent resource exhaustion and infinite loops in edge cases.

Recommendation: Request changes to add at least a maximum total retry duration before merging.

---

Review generated with Claude Code

[claude]

Pull Request Review: Refine Reconnect Strategy in Azure ASR Extension

Summary

This PR changes the Azure ASR extension's reconnection strategy from a limited retry approach (5 attempts) to an unlimited retry approach with exponential backoff. Similar changes are applied to the Tencent ASR extension.

---

Positive Aspects

1. Improved Resilience

• Unlimited retries prevent complete service failure due to temporary network issues
• The exponential backoff strategy (0.5s to 1s to 2s to 4s max) prevents overwhelming the service provider
• This is a reasonable approach for real-time ASR services where transient failures are common

2. Good Test Coverage

• Added test_unlimited_reconnect.py with comprehensive test simulating 8 failures
• Test properly verifies that the system continues beyond the old 5-attempt limit
• Good use of mocking to simulate failure scenarios

3. Code Quality

• Clean refactoring with removal of the can_retry() method that is no longer needed
• Updated documentation and comments accurately reflect the new behavior
• Version bumps appropriately applied

---

Critical Concerns

1. Lack of Circuit Breaker / Escape Mechanism

Severity: HIGH

The unlimited retry strategy has no escape mechanism for persistent failures. Consider these scenarios:

• Invalid credentials: Will retry forever instead of failing fast
• Service deprecation/shutdown: Will continue attempting indefinitely
• Configuration errors: No way to signal unrecoverable errors

Recommendation: Implement a circuit breaker pattern to detect persistent failures and alert operators.

2. Error Reporting Issues

Severity: MEDIUM

In reconnect_manager.py:102-109, every reconnection failure reports a FATAL_ERROR. This is problematic because FATAL_ERROR is semantically incorrect if the system will keep retrying. This may flood error monitoring systems with false alarms and makes it difficult to distinguish between temporary and permanent failures.

Recommendation:

• Use a different error code (e.g., TRANSIENT_ERROR or RETRY_ERROR) for retry attempts
• Only use FATAL_ERROR for truly unrecoverable situations
• Consider throttling error reports (e.g., only report every Nth failure)

3. Missing Graceful Shutdown Mechanism

Severity: MEDIUM

With unlimited retries, there is no clean way to stop the reconnection loop. A shutdown flag should be added to allow clean exit from retry loops.

4. Memory Leak Risk

Severity: LOW-MEDIUM

The attempts counter in reconnect_manager.py:70 grows indefinitely without bounds. While an integer overflow is unlikely in Python, this could cause issues in long-running processes.

Recommendation: Cap the counter or reset it periodically.

---

Code-Specific Issues

5. Inconsistent Visibility Change

In reconnect_manager.py:33, reset_counter() was changed from public to private. This changes the public API without clear justification. If external code depends on reset_counter(), this is a breaking change.

6. Outdated Comment in extension.py

The method comment at azure_asr_python/extension.py:520 mentions "max attempts are reached" which is now outdated. It should be updated to reflect unlimited retries.

---

Architecture & Design Concerns

7. Inconsistency with Other ASR Extensions

Severity: MEDIUM

The codebase has 12+ other ASR extensions with ReconnectManager classes. This PR only updates Azure and Tencent extensions.

Questions:

• Do all ASR extensions need this change?
• Is there a reason only Azure/Tencent are updated?
• Should this be a shared utility to maintain consistency?

Recommendation: Consider extracting ReconnectManager to a shared module and applying the unlimited retry strategy consistently across all ASR extensions.

8. Configuration Flexibility

Severity: LOW

The retry parameters are hardcoded (base_delay = 0.5, max_delay = 4.0). For the Tencent extension these are passed as parameters, which is good. For Azure, they use defaults.

Recommendation: Consider making these configurable via manifest/config files for operational flexibility.

---

Testing Gaps

9. Missing Test Cases

The new test file test_unlimited_reconnect.py is good but could be improved with additional scenarios:

• Test immediate success (0 failures)
• Test that exponential backoff delays are correct
• Test behavior during graceful shutdown
• Test that error counts are accurate for intermediate failure counts
• Test max_delay cap is working (verify delay does not exceed 4s)

---

Security Considerations

10. Resource Exhaustion

Severity: MEDIUM

Unlimited retries could be exploited where an attacker causing continuous connection failures could keep the system in a retry loop indefinitely. This consumes CPU, memory, and logging resources.

Recommendation:

• Implement rate limiting or exponential backoff ceiling
• Add monitoring/alerting for excessive retry attempts
• Consider connection attempt quotas per time window

---

Minor Issues

11. Test File Change in test_multi_language.py

The audio file name change from "16k_zh_cn_hotwords.pcm" to "16k_zh_cn.pcm" seems unrelated to the PR's main purpose. If this is a bug fix, mention it in the PR description.

12. Documentation Clarity

In reconnect_manager.py:13, consider clarifying "0.5s, 1s, 2s, 4s (capped)" to "0.5s, 1s, 2s, 4s, 4s, 4s..." to make it clear the delay stays at 4s.

---

Recommendations Summary

High Priority:

1. Add circuit breaker pattern to detect persistent failures
2. Change error severity from FATAL_ERROR to appropriate level for retries
3. Add graceful shutdown mechanism for clean exit from retry loop
4. Update outdated comment in extension.py:520

Medium Priority:

5. Evaluate consistency across all ASR extensions - should this be a shared module?
6. Add monitoring/alerting for excessive retry scenarios
7. Cap the attempts counter to prevent unbounded growth

Low Priority:

8. Make retry parameters configurable
9. Expand test coverage for edge cases
10. Document the audio file name change if intentional

---

Final Verdict

Overall Assessment: The PR improves resilience but introduces operational risks due to the lack of escape mechanisms for persistent failures.

Recommendation: Request Changes - the PR needs circuit breaker logic and proper error classification before merging to production.

The core idea is sound, but production systems need safeguards against infinite retry loops. With the suggested improvements, this would be a solid enhancement to the ASR extensions.