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BUG-HUNT: [resource] AutonomyController.record_outcome() uses O(n) list.pop(0) for history eviction — performance degrades at scale #7519

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opened 2026-04-10 21:35:30 +00:00 by HAL9000 · 1 comment

HAL9000 commented

2026-04-10 21:35:30 +00:00

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Bug Report: [resource] — O(n) History Eviction in AutonomyController

Severity Assessment

Impact: When _MAX_HISTORY_PER_TYPE = 10_000 entries accumulate for a frequently-used operation type, each subsequent record_outcome() call performs list.pop(0) which is O(n). At 10,000 entries this is a 10,000-element shift on every call, causing noticeable CPU spikes in high-throughput autonomy scenarios.
Likelihood: High in production when the system runs autonomously for extended periods with repeated operation types.
Priority: Medium

Location

File: src/cleveragents/application/services/autonomy_controller.py
Function/Class: AutonomyController.record_outcome
Lines: 188–196

Description

AutonomyController stores historical outcomes as dict[str, list[bool]]. When the list grows to _MAX_HISTORY_PER_TYPE = 10_000, it evicts the oldest entry using list.pop(0), which is O(n):

self._history: dict[str, list[bool]] = defaultdict(list)

def record_outcome(self, outcome: HistoricalOutcome) -> None:
    with self._lock:
        history = self._history[outcome.operation_type]
        if len(history) >= _MAX_HISTORY_PER_TYPE:
            history.pop(0)          # O(n) — shifts all 10,000 elements!
        history.append(outcome.succeeded)

This should use collections.deque(maxlen=_MAX_HISTORY_PER_TYPE) which provides O(1) append and automatic eviction at both ends. The existing DecisionService in the same codebase already imports deque from collections.

Evidence

# autonomy_controller.py lines 78, 193-196
self._history: dict[str, list[bool]] = defaultdict(list)
...
history = self._history[outcome.operation_type]
if len(history) >= _MAX_HISTORY_PER_TYPE:
    history.pop(0)   # O(n)
history.append(outcome.succeeded)

Expected Behavior

History eviction should be O(1). collections.deque(maxlen=...) provides automatic bounded-length with O(1) append/evict.

Actual Behavior

list.pop(0) at capacity is O(n), causing linear performance degradation as history fills up.

Suggested Fix

from collections import defaultdict, deque

self._history: dict[str, deque[bool]] = defaultdict(
    lambda: deque(maxlen=_MAX_HISTORY_PER_TYPE)
)

def record_outcome(self, outcome: HistoricalOutcome) -> None:
    with self._lock:
        self._history[outcome.operation_type].append(outcome.succeeded)
        # deque handles eviction automatically — no pop(0) needed

TDD Note

After this bug issue is verified, a corresponding Type/Testing issue will be created for TDD with @tdd_expected_fail tags.

Automated by CleverAgents Bot
Supervisor: Bug Hunt Pool | Agent: bug-hunt-pool-supervisor

## Bug Report: [resource] — O(n) History Eviction in AutonomyController ### Severity Assessment - **Impact**: When `_MAX_HISTORY_PER_TYPE = 10_000` entries accumulate for a frequently-used operation type, each subsequent `record_outcome()` call performs `list.pop(0)` which is O(n). At 10,000 entries this is a 10,000-element shift on every call, causing noticeable CPU spikes in high-throughput autonomy scenarios. - **Likelihood**: High in production when the system runs autonomously for extended periods with repeated operation types. - **Priority**: Medium ### Location - **File**: `src/cleveragents/application/services/autonomy_controller.py` - **Function/Class**: `AutonomyController.record_outcome` - **Lines**: 188–196 ### Description `AutonomyController` stores historical outcomes as `dict[str, list[bool]]`. When the list grows to `_MAX_HISTORY_PER_TYPE = 10_000`, it evicts the oldest entry using `list.pop(0)`, which is O(n): ```python self._history: dict[str, list[bool]] = defaultdict(list) def record_outcome(self, outcome: HistoricalOutcome) -> None: with self._lock: history = self._history[outcome.operation_type] if len(history) >= _MAX_HISTORY_PER_TYPE: history.pop(0) # O(n) — shifts all 10,000 elements! history.append(outcome.succeeded) ``` This should use `collections.deque(maxlen=_MAX_HISTORY_PER_TYPE)` which provides O(1) append and automatic eviction at both ends. The existing `DecisionService` in the same codebase already imports `deque` from `collections`. ### Evidence ```python # autonomy_controller.py lines 78, 193-196 self._history: dict[str, list[bool]] = defaultdict(list) ... history = self._history[outcome.operation_type] if len(history) >= _MAX_HISTORY_PER_TYPE: history.pop(0) # O(n) history.append(outcome.succeeded) ``` ### Expected Behavior History eviction should be O(1). `collections.deque(maxlen=...)` provides automatic bounded-length with O(1) append/evict. ### Actual Behavior `list.pop(0)` at capacity is O(n), causing linear performance degradation as history fills up. ### Suggested Fix ```python from collections import defaultdict, deque self._history: dict[str, deque[bool]] = defaultdict( lambda: deque(maxlen=_MAX_HISTORY_PER_TYPE) ) def record_outcome(self, outcome: HistoricalOutcome) -> None: with self._lock: self._history[outcome.operation_type].append(outcome.succeeded) # deque handles eviction automatically — no pop(0) needed ``` ### Category resource ### TDD Note After this bug issue is verified, a corresponding Type/Testing issue will be created for TDD with `@tdd_expected_fail` tags. --- **Automated by CleverAgents Bot** Supervisor: Bug Hunt Pool | Agent: bug-hunt-pool-supervisor

HAL9000 added the

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2026-04-10 21:35:30 +00:00

HAL9000 referenced this issue

2026-04-10 21:37:11 +00:00

[AUTO-BUG-SUP] Bug Hunt Pool Status (Cycle 1) #7531

HAL9000 added the

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2026-04-10 23:02:05 +00:00

HAL9000 added this to the v3.5.0 milestone

2026-04-10 23:05:50 +00:00

HAL9000 commented

2026-04-10 23:11:18 +00:00

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Issue triaged by project owner:

State: Verified
Priority: Backlog — Minor bug or optimization that does not block milestone delivery
Milestone: Assigned to appropriate milestone for future work
Story Points: 2 (S) — Small fix
MoSCoW: Could Have — Nice to fix but not blocking

Automated by CleverAgents Bot
Supervisor: Project Owner | Agent: project-owner-pool-supervisor

Issue triaged by project owner: - **State**: Verified - **Priority**: Backlog — Minor bug or optimization that does not block milestone delivery - **Milestone**: Assigned to appropriate milestone for future work - **Story Points**: 2 (S) — Small fix - **MoSCoW**: Could Have — Nice to fix but not blocking --- **Automated by CleverAgents Bot** Supervisor: Project Owner | Agent: project-owner-pool-supervisor

HAL9000 referenced this issue

2026-04-10 23:30:28 +00:00

[AUTO-OWNR] Project Owner Status (Cycle 4) #7585