Problem
The core agent.py contains multiple global and class-level mutable variables accessed without any thread synchronization, violating the "multi-agent + async safe by default" engineering principle.
This causes race conditions when multiple agents run concurrently — a core use case for PraisonAI.
Specific Locations
1. Unprotected HTTP server globals (agent.py lines 143-145)
_server_started = {} # Dict of port -> started boolean (NO LOCK)
_registered_agents = {} # Dict of port -> Dict (NO LOCK)
_shared_apps = {} # Dict of port -> FastAPI app (NO LOCK)Risk: Multiple agents calling .launch() on different ports concurrently will race on dict updates.
2. Non-atomic class counter (agent.py lines 157, 1254)
_agent_counter = 0 # Class-level, incremented without lock
# ...
Agent._agent_counter += 1 # NOT atomic — two threads can get duplicate indices
3. Thread-unsafe lazy loaders (agent.py lines 16-94)
Six manual lazy-loader functions (_get_console, _get_live, _get_llm_functions, _get_display_functions, _get_hooks_module, _get_stream_emitter) use classic TOCTOU pattern:
_rich_console = None
def _get_console():
global _rich_console
if _rich_console is None: # Thread A checks
from rich.console import Console # Thread B also checks, both import
_rich_console = Console()
return _rich_consoleCompare to the correct pattern already in _lazy.py (lines 61-74) with double-checked locking.
4. Same issue in context_agent.py (lines 22-57)
Four more manual lazy loaders (_get_subprocess, _get_glob, _get_ast, _get_asyncio) with the same unsafe pattern.
5. Tools module instance cache (tools/__init__.py line 188, 256-259)
_instances = {} # Module-level dict accessed without locks
# ...
_instances[class_name] = class_() # No lock protectionExpected Behavior
All global/class-level mutable state should be protected with threading.Lock() or threading.RLock(), consistent with the existing thread-safe patterns in:
_lazy.py (double-checked locking)tools/registry.py (RLock on all operations)
Proposed Fix
- Replace manual lazy loaders in
agent.py and context_agent.py with the centralized _lazy.py utilities (lazy_import() or create_lazy_getattr())
- Add
threading.Lock() around _server_started, _registered_agents, _shared_apps mutations
- Protect
_agent_counter increment with a class-level lock
- Add lock to
tools/__init__.py _instances dict
Impact
- Severity: High — affects any multi-agent deployment
- Principle violated: "Multi-agent + async safe by default"
- Existing fix pattern: Already implemented correctly in
_lazy.py and tools/registry.py
Problem
The core
agent.pycontains multiple global and class-level mutable variables accessed without any thread synchronization, violating the "multi-agent + async safe by default" engineering principle.This causes race conditions when multiple agents run concurrently — a core use case for PraisonAI.
Specific Locations
1. Unprotected HTTP server globals (
agent.pylines 143-145)Risk: Multiple agents calling
.launch()on different ports concurrently will race on dict updates.2. Non-atomic class counter (
agent.pylines 157, 1254)3. Thread-unsafe lazy loaders (
agent.pylines 16-94)Six manual lazy-loader functions (
_get_console,_get_live,_get_llm_functions,_get_display_functions,_get_hooks_module,_get_stream_emitter) use classic TOCTOU pattern:Compare to the correct pattern already in
_lazy.py(lines 61-74) with double-checked locking.4. Same issue in
context_agent.py(lines 22-57)Four more manual lazy loaders (
_get_subprocess,_get_glob,_get_ast,_get_asyncio) with the same unsafe pattern.5. Tools module instance cache (
tools/__init__.pyline 188, 256-259)Expected Behavior
All global/class-level mutable state should be protected with
threading.Lock()orthreading.RLock(), consistent with the existing thread-safe patterns in:_lazy.py(double-checked locking)tools/registry.py(RLock on all operations)Proposed Fix
agent.pyandcontext_agent.pywith the centralized_lazy.pyutilities (lazy_import()orcreate_lazy_getattr())threading.Lock()around_server_started,_registered_agents,_shared_appsmutations_agent_counterincrement with a class-level locktools/__init__.py_instancesdictImpact
_lazy.pyandtools/registry.py