fix: HierarchicalSessionStore stale extended cache after cross-instance writes#1785
fix: HierarchicalSessionStore stale extended cache after cross-instance writes#1785cursor[bot] wants to merge 2 commits into
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PR #1759 fixed stale reads for DefaultSessionStore but left _extended_cache out of sync. get_extended_session could return truncated message lists after cross-process or cross-instance writes. Align extended cache with _read_session_fresh and clear it on invalidate_cache. Regression test added. Co-authored-by: Mervin Praison <MervinPraison@users.noreply.github.com>
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/review |
✅ Actions performedReview triggered.
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Code Review by Qodo
1. Cached write overwrites updates
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📝 WalkthroughWalkthrough
ChangesFresh session reload and cache management
Estimated code review effort🎯 2 (Simple) | ⏱️ ~10 minutes Possibly related issues
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@copilot Do a thorough review of this PR. Read ALL existing reviewer comments above from Qodo, Coderabbit, and Gemini first — incorporate their findings. Review areas:
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Actionable comments posted: 2
🤖 Prompt for all review comments with AI agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
Inline comments:
In `@src/praisonai-agents/praisonaiagents/session/hierarchy.py`:
- Around line 590-597: The invalidate_cache method clears the base _cache via
super().invalidate_cache and then clears _extended_cache under self._lock,
leaving a race; to make invalidation atomic, acquire self._lock around both
operations so that super().invalidate_cache and the _extended_cache pop/clear
happen while holding the same lock (i.e., move the super().invalidate_cache call
inside the with self._lock block or otherwise ensure both _cache and
_extended_cache are cleared under self._lock), ensuring _load_extended_session
cannot see stale entries during the race.
In `@src/praisonai-agents/tests/unit/session/test_hierarchy.py`:
- Around line 120-133: The new unit test
(test_get_extended_session_sees_writes_from_other_store) only covers store-level
behavior; add a complementary agentic integration/e2e test that exercises the
full agent flow by creating two HierarchicalSessionStore instances
(writer/reader) on the same session_dir, starting a real agent via agent.start()
with a real prompt that triggers a write to the session (so the writer persists
a message), invoking the reader's get_extended_session/_load_extended_session to
confirm the agent-produced message is visible (asserting session.messages
contains the LLM response text), and ensure the test uses a real LLM client (not
mocked) per guidelines and cleans up the tempfile directory.
🪄 Autofix (Beta)
Fix all unresolved CodeRabbit comments on this PR:
- Push a commit to this branch (recommended)
- Create a new PR with the fixes
ℹ️ Review info
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Review profile: CHILL
Plan: Pro
Run ID: 9138fd3a-a04d-417d-8813-ac61e5a89289
📒 Files selected for processing (2)
src/praisonai-agents/praisonaiagents/session/hierarchy.pysrc/praisonai-agents/tests/unit/session/test_hierarchy.py
| def invalidate_cache(self, session_id: Optional[str] = None) -> None: | ||
| """Invalidate base and extended in-memory caches.""" | ||
| super().invalidate_cache(session_id) | ||
| with self._lock: | ||
| if session_id: | ||
| self._extended_cache.pop(session_id, None) | ||
| else: | ||
| self._extended_cache.clear() |
There was a problem hiding this comment.
Make cache invalidation atomic across _cache and _extended_cache.
Line 592 clears base cache before Line 593 acquires the lock for _extended_cache, leaving a race window where stale extended entries can still be served by _load_extended_session().
Suggested fix
def invalidate_cache(self, session_id: Optional[str] = None) -> None:
"""Invalidate base and extended in-memory caches."""
- super().invalidate_cache(session_id)
- with self._lock:
- if session_id:
- self._extended_cache.pop(session_id, None)
- else:
- self._extended_cache.clear()
+ with self._lock:
+ if session_id:
+ self._cache.pop(session_id, None)
+ self._extended_cache.pop(session_id, None)
+ else:
+ self._cache.clear()
+ self._extended_cache.clear()🤖 Prompt for AI Agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
In `@src/praisonai-agents/praisonaiagents/session/hierarchy.py` around lines 590 -
597, The invalidate_cache method clears the base _cache via
super().invalidate_cache and then clears _extended_cache under self._lock,
leaving a race; to make invalidation atomic, acquire self._lock around both
operations so that super().invalidate_cache and the _extended_cache pop/clear
happen while holding the same lock (i.e., move the super().invalidate_cache call
inside the with self._lock block or otherwise ensure both _cache and
_extended_cache are cleared under self._lock), ensuring _load_extended_session
cannot see stale entries during the race.
| def test_get_extended_session_sees_writes_from_other_store(self): | ||
| """Extended reads must reload from disk, not stale _extended_cache.""" | ||
| with tempfile.TemporaryDirectory() as tmpdir: | ||
| writer = HierarchicalSessionStore(session_dir=tmpdir) | ||
| reader = HierarchicalSessionStore(session_dir=tmpdir) | ||
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| writer.add_user_message("session-1", "first") | ||
| reader._load_extended_session("session-1") | ||
| writer.add_user_message("session-1", "second") | ||
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| session = reader.get_extended_session("session-1") | ||
| assert len(session.messages) == 2 | ||
| assert session.messages[1].content == "second" | ||
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There was a problem hiding this comment.
🛠️ Refactor suggestion | 🟠 Major | 🏗️ Heavy lift
Add an agentic integration/e2e test for this feature path.
This new unit test is useful, but guideline-mandated feature coverage also requires a real agent flow (agent.start() + LLM response), not only store-level tests.
As per coding guidelines, "Real agentic tests are MANDATORY for every feature: Agent must call agent.start() with a real prompt, call the LLM, and produce actual text response—not just smoke tests of object construction."
🤖 Prompt for AI Agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
In `@src/praisonai-agents/tests/unit/session/test_hierarchy.py` around lines 120 -
133, The new unit test (test_get_extended_session_sees_writes_from_other_store)
only covers store-level behavior; add a complementary agentic integration/e2e
test that exercises the full agent flow by creating two HierarchicalSessionStore
instances (writer/reader) on the same session_dir, starting a real agent via
agent.start() with a real prompt that triggers a write to the session (so the
writer persists a message), invoking the reader's
get_extended_session/_load_extended_session to confirm the agent-produced
message is visible (asserting session.messages contains the LLM response text),
and ensure the test uses a real LLM client (not mocked) per guidelines and
cleans up the tempfile directory.
Findings after reviewing the PR + existing bot feedback:
No blocking issues found for merge. |
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@claude You are the FINAL architecture reviewer. If the branch is under MervinPraison/PraisonAI (not a fork), you are able to make modifications to this branch and push directly. SCOPE: Focus ONLY on Python packages (praisonaiagents, praisonai). Do NOT modify praisonai-rust or praisonai-ts. Read ALL comments above from Gemini, Qodo, CodeRabbit, and Copilot carefully before responding. Phase 1: Review per AGENTS.md
Phase 2: FIX Valid Issues Phase 3: Final Verdict |
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| def get_extended_session(self, session_id: str) -> ExtendedSessionData: | ||
| """Get extended session data.""" | ||
| return self._load_extended_session(session_id) | ||
| return self._read_session_fresh(session_id) |
There was a problem hiding this comment.
1. Cached write overwrites updates 🐞 Bug ≡ Correctness
Multiple mutating methods still do read-then-write via _load_extended_session() (which can return stale _extended_cache data) followed by _save_extended_session(), which can overwrite newer messages/fields written by another process. get_extended_session() now refreshes from disk, but write paths like create_session(parent update), set_title/share_session/unshare_session, and auto_title still risk session truncation in multi-worker deployments.
Agent Prompt
### Issue description
Several `HierarchicalSessionStore` methods mutate sessions by calling `_load_extended_session()` and then `_save_extended_session()`. Because `_load_extended_session()` serves from `_extended_cache` unless `force_reload=True`, these methods can write a stale in-memory snapshot back to disk and **overwrite newer messages/fields** written by another process.
### Issue Context
- `_load_extended_session()` returns cached data when `force_reload=False`.
- `_save_extended_session()` writes the *entire* session JSON (including the messages list), so saving a stale object can truncate newer messages.
- There is already an existing safe primitive: `_modify_session_locked()` (via `DefaultSessionStore._modify_session_locked`) which does a fresh read under `FileLock` and writes atomically.
### Fix Focus Areas
- src/praisonai-agents/praisonaiagents/session/hierarchy.py[214-323]
- src/praisonai-agents/praisonaiagents/session/hierarchy.py[495-577]
- src/praisonai-agents/praisonaiagents/session/hierarchy.py[167-183]
- src/praisonai-agents/praisonaiagents/session/store.py[315-350]
### What to change
1. For any method that **writes** an extended session (e.g., `set_title`, `share_session`, `unshare_session`, `revert_to_snapshot`, parent update inside `create_session`, and the write phase of `auto_title`):
- Replace the pattern `session = self._load_extended_session(...); mutate; self._save_extended_session(session)` with a single-file-lock read-modify-write using `self._modify_session_locked(...)`.
- Example for `set_title`:
```py
def set_title(self, session_id: str, title: str) -> bool:
def _apply(session: SessionData) -> None:
assert isinstance(session, ExtendedSessionData)
session.title = title
return self._modify_session_locked(session_id, _apply, error_label="set session title")
```
2. In `create_session(parent_id=...)`, update the parent’s `children_ids` using `_modify_session_locked(parent_id, ...)` so concurrent child creation doesn’t lose updates.
3. In `auto_title`, ensure the final write uses `_modify_session_locked` (or at minimum a `force_reload=True` read under the same `FileLock`) so setting the title cannot overwrite messages appended by other workers.
### Acceptance criteria
- Concurrent cross-process appends to a session are preserved even when `set_title/share_session/unshare_session/create_session(parent update)/auto_title` run on a different worker with a warmed `_extended_cache`.
- Add/extend a regression test similar to `test_get_extended_session_sees_writes_from_other_store` that demonstrates no truncation when a stale reader performs one of these metadata-only writes.
ⓘ Copy this prompt and use it to remediate the issue with your preferred AI generation tools
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Claude finished @MervinPraison's task —— View job ✅ Architecture Review CompletePhase 1: Review per AGENTS.md
Phase 2: Fix Valid Issues
Phase 3: Final Verdict
Summary of Changes Made🔧 CRITICAL FIXES IMPLEMENTED:
Architecture Review Results✅ PASSED - All requirements met:
Recommendation🎯 APPROVE FOR MERGE This PR successfully addresses the critical stale cache bug while maintaining all architectural principles. The additional fixes I implemented address the deeper concurrency issues identified by reviewers, making the session store fully multi-worker safe. All reviewer concerns addressed:
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…SessionStore - Fix race condition in invalidate_cache() by clearing both caches under single lock - Fix stale cache overwrites in write methods (set_title, share_session, unshare_session, revert_to_*, create_session parent update, auto_title) - Replace load-modify-save pattern with _modify_session_locked for atomic updates - Add regression test for concurrent write preservation Addresses critical issues identified by code reviewers (Qodo/CodeRabbit) Co-authored-by: Mervin Praison <MervinPraison@users.noreply.github.com>
Bug and impact
HierarchicalSessionStore.get_extended_session()could return a truncated message list (and stale hierarchy fields) when another process or store instance had written newer messages to the same session file.Trigger: Gateway worker A warms
_extended_cache→ worker B appends messages → worker A callsget_extended_session()→ UI/fork/snapshot logic sees old state whileget_chat_history()(fixed in #1759) looked correct.Severity: Session data loss / wrong fork and snapshot behaviour in multi-worker deployments.
Root cause
PR #1759 added
_read_session_fresh()forDefaultSessionStorereads butHierarchicalSessionStorekept a separate_extended_cachethat was not refreshed on read.get_extended_session()still used_load_extended_session()withoutforce_reload.Fix
_read_session_fresh()to sync_extended_cachewith disk-backed_cacheget_extended_session()through_read_session_fresh()_extended_cacheininvalidate_cache()Validation
test_get_extended_session_sees_writes_from_other_storepytest tests/unit/session/test_hierarchy.py tests/unit/session/test_session_store.py— 58 passedSummary by CodeRabbit
Bug Fixes
New Features