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Merged
chaliy merged 1 commit into from
Mar 1, 2026
Merged

fix(python): release GIL before blocking on tokio runtime #450

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119 changes: 67 additions & 52 deletions crates/bashkit-python/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -233,41 +233,47 @@ impl PyBash {
}

/// Execute commands synchronously (blocking).
fn execute_sync(&self, commands: String) -> PyResult<ExecResult> {
/// Releases GIL before blocking on tokio to prevent deadlock with callbacks.
fn execute_sync(&self, py: Python<'_>, commands: String) -> PyResult<ExecResult> {
let inner = self.inner.clone();
let rt = tokio::runtime::Runtime::new()
.map_err(|e| PyRuntimeError::new_err(format!("Failed to create runtime: {}", e)))?;

rt.block_on(async move {
let mut bash = inner.lock().await;
match bash.exec(&commands).await {
Ok(result) => Ok(ExecResult {
stdout: result.stdout,
stderr: result.stderr,
exit_code: result.exit_code,
error: None,
}),
Err(e) => Ok(ExecResult {
stdout: String::new(),
stderr: String::new(),
exit_code: 1,
error: Some(e.to_string()),
}),
}
py.detach(|| {
rt.block_on(async move {
let mut bash = inner.lock().await;
match bash.exec(&commands).await {
Ok(result) => Ok(ExecResult {
stdout: result.stdout,
stderr: result.stderr,
exit_code: result.exit_code,
error: None,
}),
Err(e) => Ok(ExecResult {
stdout: String::new(),
stderr: String::new(),
exit_code: 1,
error: Some(e.to_string()),
}),
}
})
})
}

/// Reset interpreter to fresh state.
fn reset(&self) -> PyResult<()> {
/// Releases GIL before blocking on tokio to prevent deadlock.
fn reset(&self, py: Python<'_>) -> PyResult<()> {
let inner = self.inner.clone();
let rt = tokio::runtime::Runtime::new()
.map_err(|e| PyRuntimeError::new_err(format!("Failed to create runtime: {}", e)))?;

rt.block_on(async move {
let mut bash = inner.lock().await;
let builder = Bash::builder();
*bash = builder.build();
Ok(())
py.detach(|| {
rt.block_on(async move {
let mut bash = inner.lock().await;
let builder = Bash::builder();
*bash = builder.build();
Ok(())
})
})
}

Expand Down Expand Up @@ -378,40 +384,46 @@ impl BashTool {
})
}

fn execute_sync(&self, commands: String) -> PyResult<ExecResult> {
/// Releases GIL before blocking on tokio to prevent deadlock with callbacks.
fn execute_sync(&self, py: Python<'_>, commands: String) -> PyResult<ExecResult> {
let inner = self.inner.clone();
let rt = tokio::runtime::Runtime::new()
.map_err(|e| PyRuntimeError::new_err(format!("Failed to create runtime: {}", e)))?;

rt.block_on(async move {
let mut bash = inner.lock().await;
match bash.exec(&commands).await {
Ok(result) => Ok(ExecResult {
stdout: result.stdout,
stderr: result.stderr,
exit_code: result.exit_code,
error: None,
}),
Err(e) => Ok(ExecResult {
stdout: String::new(),
stderr: String::new(),
exit_code: 1,
error: Some(e.to_string()),
}),
}
py.detach(|| {
rt.block_on(async move {
let mut bash = inner.lock().await;
match bash.exec(&commands).await {
Ok(result) => Ok(ExecResult {
stdout: result.stdout,
stderr: result.stderr,
exit_code: result.exit_code,
error: None,
}),
Err(e) => Ok(ExecResult {
stdout: String::new(),
stderr: String::new(),
exit_code: 1,
error: Some(e.to_string()),
}),
}
})
})
}

fn reset(&self) -> PyResult<()> {
/// Releases GIL before blocking on tokio to prevent deadlock.
fn reset(&self, py: Python<'_>) -> PyResult<()> {
let inner = self.inner.clone();
let rt = tokio::runtime::Runtime::new()
.map_err(|e| PyRuntimeError::new_err(format!("Failed to create runtime: {}", e)))?;

rt.block_on(async move {
let mut bash = inner.lock().await;
let builder = Bash::builder();
*bash = builder.build();
Ok(())
py.detach(|| {
rt.block_on(async move {
let mut bash = inner.lock().await;
let builder = Bash::builder();
*bash = builder.build();
Ok(())
})
})
}

Expand Down Expand Up @@ -652,17 +664,20 @@ impl ScriptedTool {
}

/// Execute a bash script synchronously (blocking).
fn execute_sync(&self, commands: String) -> PyResult<ExecResult> {
/// Releases GIL before blocking on tokio to prevent deadlock with callbacks.
fn execute_sync(&self, py: Python<'_>, commands: String) -> PyResult<ExecResult> {
let mut tool = self.build_rust_tool();
let rt = tokio::runtime::Runtime::new()
.map_err(|e| PyRuntimeError::new_err(format!("Failed to create runtime: {}", e)))?;

let resp = rt.block_on(async move {
tool.execute(ToolRequest {
commands,
timeout_ms: None,
let resp = py.detach(|| {
rt.block_on(async move {
tool.execute(ToolRequest {
commands,
timeout_ms: None,
})
.await
})
.await
});
Ok(ExecResult {
stdout: resp.stdout,
Expand Down
120 changes: 120 additions & 0 deletions crates/bashkit-python/tests/test_bashkit.py
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Original file line number Diff line number Diff line change
Expand Up @@ -728,3 +728,123 @@ async def test_async_multiple_tools():
assert r.exit_code == 0
assert "A" in r.stdout
assert "B" in r.stdout


# ===========================================================================
# GIL deadlock prevention tests
# ===========================================================================


def test_execute_sync_releases_gil_for_callback():
"""execute_sync must release GIL before blocking on tokio runtime.

Without py.allow_threads(), a tool callback calling Python::attach()
inside rt.block_on() can deadlock when another thread holds the GIL.
This test validates the fix by running execute_sync with a callback
from a background thread while the main thread also holds the GIL.
"""
import threading
import time

tool = ScriptedTool("api")

def slow_callback(params, stdin=None):
"""Callback that briefly sleeps, requiring GIL reacquisition."""
time.sleep(0.01)
return f"ok-{params.get('id', 0)}\n"

tool.add_tool(
"slow",
"Slow command",
callback=slow_callback,
schema={"type": "object", "properties": {"id": {"type": "integer"}}},
)

results = [None, None]
errors = [None, None]

def run_in_thread(idx):
try:
r = tool.execute_sync(f"slow --id {idx}")
results[idx] = r
except Exception as e:
errors[idx] = e

t0 = threading.Thread(target=run_in_thread, args=(0,))
t1 = threading.Thread(target=run_in_thread, args=(1,))

t0.start()
t1.start()

# Timeout guards against deadlock — if GIL isn't released, threads block forever
t0.join(timeout=10)
t1.join(timeout=10)

assert not t0.is_alive(), "Thread 0 deadlocked (GIL not released in execute_sync)"
assert not t1.is_alive(), "Thread 1 deadlocked (GIL not released in execute_sync)"
assert errors[0] is None, f"Thread 0 error: {errors[0]}"
assert errors[1] is None, f"Thread 1 error: {errors[1]}"
assert results[0].exit_code == 0
assert results[1].exit_code == 0
assert "ok-0" in results[0].stdout
assert "ok-1" in results[1].stdout


def test_bash_execute_sync_releases_gil():
"""Bash.execute_sync must release GIL before blocking on tokio runtime."""
import threading

bash = Bash()
results = [None, None]
errors = [None, None]

def run_in_thread(idx):
try:
r = bash.execute_sync(f"echo thread-{idx}")
results[idx] = r
except Exception as e:
errors[idx] = e

t0 = threading.Thread(target=run_in_thread, args=(0,))
t1 = threading.Thread(target=run_in_thread, args=(1,))

t0.start()
t1.start()

t0.join(timeout=10)
t1.join(timeout=10)

assert not t0.is_alive(), "Thread 0 deadlocked (GIL not released)"
assert not t1.is_alive(), "Thread 1 deadlocked (GIL not released)"
assert errors[0] is None, f"Thread 0 error: {errors[0]}"
assert errors[1] is None, f"Thread 1 error: {errors[1]}"


def test_bashtool_execute_sync_releases_gil():
"""BashTool.execute_sync must release GIL before blocking on tokio runtime."""
import threading

tool = BashTool()
results = [None, None]
errors = [None, None]

def run_in_thread(idx):
try:
r = tool.execute_sync(f"echo thread-{idx}")
results[idx] = r
except Exception as e:
errors[idx] = e

t0 = threading.Thread(target=run_in_thread, args=(0,))
t1 = threading.Thread(target=run_in_thread, args=(1,))

t0.start()
t1.start()

t0.join(timeout=10)
t1.join(timeout=10)

assert not t0.is_alive(), "Thread 0 deadlocked (GIL not released)"
assert not t1.is_alive(), "Thread 1 deadlocked (GIL not released)"
assert errors[0] is None, f"Thread 0 error: {errors[0]}"
assert errors[1] is None, f"Thread 1 error: {errors[1]}"
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