> ## Documentation Index
> Fetch the complete documentation index at: https://docs.praison.ai/llms.txt
> Use this file to discover all available pages before exploring further.
# Async Bridge
> Safely call async code from sync, and sync code from async, without deadlocking the event loop.
The async bridge lets your tools and callbacks move between sync and async without crashing the event loop.
```mermaid theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
graph LR
subgraph "Async Bridge"
A[๐ Sync Caller] --> B{๐ Loop Check}
B -->|No Loop| C[๐ Run Coroutine]
B -->|Loop Running| D[โ RuntimeError]
C --> E[โ
Result]
F[๐ Async Caller] --> G[๐งต Executor]
G --> H[โ
Result]
end
classDef input fill:#6366F1,stroke:#7C90A0,color:#fff
classDef process fill:#F59E0B,stroke:#7C90A0,color:#fff
classDef output fill:#10B981,stroke:#7C90A0,color:#fff
classDef error fill:#8B0000,stroke:#7C90A0,color:#fff
class A,F input
class B,C,G process
class E,H output
class D error
```
## Quick Start
Use `run_coroutine_from_any_context` to call async code from a sync tool:
```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
from praisonaiagents import Agent
from praisonaiagents.utils.async_bridge import run_coroutine_from_any_context
import httpx
async def _fetch(url: str) -> str:
async with httpx.AsyncClient() as client:
return (await client.get(url)).text[:500]
def fetch_sync(url: str) -> str:
"""Sync tool that safely reuses an async HTTP client."""
return run_coroutine_from_any_context(_fetch(url))
agent = Agent(
name="Researcher",
instructions="Fetch and summarise web pages",
tools=[fetch_sync],
)
agent.start("Summarise https://example.com")
```
Use `run_sync_in_executor` to call blocking code from an async tool without blocking the event loop:
```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
from praisonaiagents import Agent
from praisonaiagents.utils.async_bridge import run_sync_in_executor
import time
def blocking_task(duration: int) -> str:
time.sleep(duration)
return f"Completed after {duration} seconds"
async def async_tool(duration: int) -> str:
"""Async tool that offloads blocking work."""
return await run_sync_in_executor(blocking_task, duration)
agent = Agent(
name="Worker",
instructions="Handle blocking tasks efficiently",
tools=[async_tool],
)
```
Use `is_async_context` to create dual-mode helpers:
```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
from praisonaiagents.utils.async_bridge import is_async_context, run_coroutine_from_any_context
import httpx
async def _async_fetch(url: str) -> str:
async with httpx.AsyncClient() as client:
return (await client.get(url)).text
def smart_fetch(url: str) -> str:
"""Context-aware fetch that works in both sync and async."""
if is_async_context():
raise RuntimeError("Use await smart_fetch_async(url) in async context")
return run_coroutine_from_any_context(_async_fetch(url))
async def smart_fetch_async(url: str) -> str:
"""Async version for use in async contexts."""
return await _async_fetch(url)
```
***
## How It Works
```mermaid theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
sequenceDiagram
participant Caller
participant Bridge
participant EventLoop
participant Executor
Caller->>Bridge: run_coroutine_from_any_context(coro)
Bridge->>EventLoop: get_running_loop()
EventLoop-->>Bridge: RuntimeError (no loop)
Bridge->>EventLoop: asyncio.run(coro)
EventLoop-->>Bridge: Result
Bridge-->>Caller: Result
Note over Bridge,EventLoop: If loop exists, raises RuntimeError
Caller->>Bridge: await run_sync_in_executor(func, args)
Bridge->>Executor: submit(func, args)
Executor-->>Bridge: Result
Bridge-->>Caller: Result
```
The bridge probes for a running event loop using `asyncio.get_running_loop()`. If no loop exists, it safely creates one with `asyncio.run()`. If a loop is already running, it raises `RuntimeError` to prevent deadlocks.
***
## Configuration Options
| Option | Type | Default | Description |
| --------- | ------- | ------- | ------------------------------------------------ |
| `timeout` | `float` | `300` | Maximum seconds to wait for coroutine completion |
***
## Common Patterns
### Reusing async SDKs from sync tools
```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
from praisonaiagents import Agent
from praisonaiagents.utils.async_bridge import run_coroutine_from_any_context
import aiofiles
async def _read_file_async(path: str) -> str:
async with aiofiles.open(path) as f:
return await f.read()
def read_file(path: str) -> str:
"""Sync wrapper for async file operations."""
return run_coroutine_from_any_context(_read_file_async(path))
agent = Agent(
name="FileReader",
instructions="Process files efficiently",
tools=[read_file],
)
```
### Offloading blocking calls from async tools
```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
import subprocess
from praisonaiagents.utils.async_bridge import run_sync_in_executor
async def run_command(cmd: str) -> str:
"""Run shell command without blocking the event loop."""
def _run():
return subprocess.check_output(cmd, shell=True, text=True)
return await run_sync_in_executor(_run)
```
### Context-aware dual-mode helper
```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
from praisonaiagents.utils.async_bridge import is_async_context, run_coroutine_from_any_context
def universal_helper(data):
"""Works in both sync and async contexts."""
if is_async_context():
raise RuntimeError("Use await universal_helper_async(data) in async context")
async def _process():
# async processing logic
await asyncio.sleep(0.1)
return f"Processed: {data}"
return run_coroutine_from_any_context(_process())
```
***
## Best Practices
Calling `run_coroutine_from_any_context` inside an `async def` raises `RuntimeError` by design. If you're in a coroutine, use `await` instead:
```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
# Good
async def my_async_tool():
result = await my_coroutine()
# Bad - will raise RuntimeError
async def my_async_tool():
result = run_coroutine_from_any_context(my_coroutine())
```
Only wrap at the true sync/async boundary. Avoid creating unnecessary bridge calls in the middle of your call stack:
```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
# Good - bridge at the boundary
def sync_tool():
return run_coroutine_from_any_context(async_logic())
# Bad - unnecessary nesting
def sync_tool():
def inner():
return run_coroutine_from_any_context(async_logic())
return inner()
```
The default 300 seconds is large for most use cases. Tighten for latency-critical tools:
```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
# Good for quick operations
result = run_coroutine_from_any_context(quick_api_call(), timeout=10)
# Good for long operations
result = run_coroutine_from_any_context(model_training(), timeout=3600)
```
When building utilities that work in both sync and async contexts, check the context first:
```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
def smart_helper():
if is_async_context():
raise RuntimeError("Use await smart_helper_async() in async context")
return run_coroutine_from_any_context(async_implementation())
async def smart_helper_async():
return await async_implementation()
```
***
## Used by
The following synchronous APIs route through `run_sync()` and therefore honour `PRAISONAI_RUN_SYNC_TIMEOUT` consistently:
* `praisonai.bots.WebhookApproval.request_approval_sync()`
* `praisonai.bots.HTTPApproval.request_approval_sync()`
* `praisonai.integrations.get_available_integrations()`
* All \~77 wrapper-side `run_sync` call sites (gateway, a2u, mcp\_server, scheduler) โ see PR #1583 for the full list.
These sync wrappers now raise `RuntimeError("run_sync() cannot be called from a running event loop; await the coroutine directly instead.")` when called from inside an active asyncio loop. Previously they would silently spawn a worker thread. **If you call any of these from async code, switch to `await request_approval(...)` (or the equivalent async method) directly.** This is a deliberate fail-fast change โ the silent thread spawn was masking architectural bugs in multi-agent setups.
***
## Troubleshooting
### RuntimeError: run\_coroutine\_from\_any\_context() cannot be called from async context
You're trying to use the bridge inside a coroutine. Use `await` instead:
```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
# Bad
async def my_coroutine():
return run_coroutine_from_any_context(other_coroutine())
# Good
async def my_coroutine():
return await other_coroutine()
```
### asyncio.run() cannot be called from a running event loop
This error used to leak from SDK internals before the async bridge was implemented. If you see this on current versions, upgrade to the latest release.
### PermissionError in approval system
The approval system now fails fast in async contexts. Configure a non-console backend:
```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
from praisonaiagents.approval import get_approval_registry, WebhookBackend
# Configure for async compatibility
get_approval_registry().set_backend(WebhookBackend(url="http://localhost:8080/approve"))
```
***
## Related
Async Agents Guide
Thread Safety & Concurrency