fix: parallelize tool call execution via JoinSet (#219) (#252)

* fix: parallelize tool call execution via JoinSet (#219)

When the LLM returns multiple tool_calls in a single response, they were
executed sequentially. This change makes both the worker and dispatcher
paths concurrent using tokio::task::JoinSet, so N independent tool calls
complete in ~max(latency) instead of sum(latency).

Worker path: migrate execute_tools_parallel from join_all to JoinSet and
route the respond_with_tools branch through the same parallel path.

Dispatcher path: restructure the while-idx loop into three phases —
preflight (sequential approval/hook checks), parallel execution via
JoinSet, and sequential post-flight processing (session recording,
auth detection, sanitization).

Also fixes a pre-existing infinite loop bug where hook rejection used
`continue` inside a `while idx` loop, skipping `idx += 1` and retrying
the same rejected tool forever.

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* fix: address PR review — ordered results, deferred auth, dedup standalone fn

- Fix auth early return skipping unrecorded tool results: defer auth
  response until after all results in the batch are recorded in session
  history and context_messages (both dispatcher and thread_ops paths)
- Fix tool results appearing out of order: collect Phase 1 hook
  rejections indexed by original position, merge with Phase 2 execution
  results, and emit all in Phase 3 in original tool_calls order
- Deduplicate execute_chat_tool: Agent method now delegates to the
  standalone function instead of duplicating 90 lines of logic
- Fix benchmark compilation: add missing session_manager arg to Agent::new

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* fix: rustfmt alignment for CI compatibility

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* fix: address second round of PR review comments

- Distinguish JoinError panic vs cancellation in log messages and error
  reasons across all 3 files (dispatcher, thread_ops, worker)
- Simplify deferred_auth from Option<(String, String)> to Option<String>
  since only the instructions string is used
- Add single-tool short-circuit in worker execute_tools_parallel to
  avoid JoinSet overhead for the common single-tool case

Co-Authored-By: Claude Opus 4.6 <[email protected]>

---------

Co-authored-by: Claude Opus 4.6 <[email protected]>
This commit is contained in:
Illia Polosukhin
2026-02-20 06:07:30 +00:00
committed by GitHub
co-authored by Claude Opus 4.6
parent 9906190de7
commit bfe393eb38
4 changed files with 951 additions and 331 deletions
+282 -22
View File
@@ -3,8 +3,8 @@
use std::sync::Arc;
use std::time::Duration;
use futures::future::join_all;
use tokio::sync::mpsc;
use tokio::task::JoinSet;
use uuid::Uuid;
use crate::agent::scheduler::WorkerMessage;
@@ -292,19 +292,21 @@ Report when the job is complete or if you encounter issues you cannot resolve."#
tool_calls.clone(),
));
for tc in tool_calls {
let result = self.execute_tool(&tc.name, &tc.arguments).await;
// Create synthetic selection for process_tool_result
let selection = ToolSelection {
// Convert ToolCalls to ToolSelections and execute in parallel
let selections: Vec<ToolSelection> = tool_calls
.iter()
.map(|tc| ToolSelection {
tool_name: tc.name.clone(),
parameters: tc.arguments.clone(),
reasoning: String::new(),
alternatives: vec![],
tool_call_id: tc.id.clone(),
};
})
.collect();
self.process_tool_result(reason_ctx, &selection, result)
let results = self.execute_tools_parallel(&selections).await;
for (selection, result) in selections.iter().zip(results) {
self.process_tool_result(reason_ctx, selection, result.result)
.await?;
}
}
@@ -347,24 +349,71 @@ Report when the job is complete or if you encounter issues you cannot resolve."#
}
}
/// Execute multiple tools in parallel.
/// Execute multiple tools in parallel using a JoinSet.
///
/// Each task is tagged with its original index so results are returned
/// in the same order as `selections`, regardless of completion order.
async fn execute_tools_parallel(&self, selections: &[ToolSelection]) -> Vec<ToolExecResult> {
let futures: Vec<_> = selections
.iter()
.map(|selection| {
let tool_name = selection.tool_name.clone();
let params = selection.parameters.clone();
let deps = self.deps.clone();
let job_id = self.job_id;
let count = selections.len();
async move {
let result = Self::execute_tool_inner(&deps, job_id, &tool_name, &params).await;
ToolExecResult { result }
// Short-circuit for single tool: execute directly without JoinSet overhead
if count <= 1 {
let mut results = Vec::with_capacity(count);
for selection in selections {
let result = Self::execute_tool_inner(
&self.deps,
self.job_id,
&selection.tool_name,
&selection.parameters,
)
.await;
results.push(ToolExecResult { result });
}
return results;
}
let mut join_set = JoinSet::new();
for (idx, selection) in selections.iter().enumerate() {
let deps = self.deps.clone();
let job_id = self.job_id;
let tool_name = selection.tool_name.clone();
let params = selection.parameters.clone();
join_set.spawn(async move {
let result = Self::execute_tool_inner(&deps, job_id, &tool_name, &params).await;
(idx, ToolExecResult { result })
});
}
// Collect and reorder by original index
let mut results: Vec<Option<ToolExecResult>> = (0..count).map(|_| None).collect();
while let Some(join_result) = join_set.join_next().await {
match join_result {
Ok((idx, exec_result)) => results[idx] = Some(exec_result),
Err(e) => {
if e.is_panic() {
tracing::error!("Tool execution task panicked: {}", e);
} else {
tracing::error!("Tool execution task cancelled: {}", e);
}
}
})
.collect();
}
}
join_all(futures).await
// Fill any panicked slots with error results
results
.into_iter()
.enumerate()
.map(|(i, opt)| {
opt.unwrap_or_else(|| ToolExecResult {
result: Err(crate::error::ToolError::ExecutionFailed {
name: selections[i].tool_name.clone(),
reason: "Task failed during execution".to_string(),
}
.into()),
})
})
.collect()
}
/// Inner tool execution logic that can be called from both single and parallel paths.
@@ -823,6 +872,102 @@ mod tests {
use crate::llm::ToolSelection;
use crate::util::llm_signals_completion;
use super::*;
use crate::config::SafetyConfig;
use crate::context::JobContext;
use crate::llm::{
CompletionRequest, CompletionResponse, LlmProvider, ToolCompletionRequest,
ToolCompletionResponse,
};
use crate::safety::SafetyLayer;
use crate::tools::{Tool, ToolError, ToolOutput};
/// A test tool that sleeps for a configurable duration before returning.
struct SlowTool {
tool_name: String,
delay: Duration,
}
#[async_trait::async_trait]
impl Tool for SlowTool {
fn name(&self) -> &str {
&self.tool_name
}
fn description(&self) -> &str {
"Test tool with configurable delay"
}
fn parameters_schema(&self) -> serde_json::Value {
serde_json::json!({"type": "object", "properties": {}})
}
async fn execute(
&self,
_params: serde_json::Value,
_ctx: &JobContext,
) -> Result<ToolOutput, ToolError> {
let start = std::time::Instant::now();
tokio::time::sleep(self.delay).await;
Ok(ToolOutput::text(
format!("done_{}", self.tool_name),
start.elapsed(),
))
}
fn requires_sanitization(&self) -> bool {
false
}
}
/// Stub LLM provider (never called in these tests).
struct StubLlm;
#[async_trait::async_trait]
impl LlmProvider for StubLlm {
fn model_name(&self) -> &str {
"stub"
}
fn cost_per_token(&self) -> (rust_decimal::Decimal, rust_decimal::Decimal) {
(rust_decimal::Decimal::ZERO, rust_decimal::Decimal::ZERO)
}
async fn complete(
&self,
_req: CompletionRequest,
) -> Result<CompletionResponse, crate::error::LlmError> {
unimplemented!("stub")
}
async fn complete_with_tools(
&self,
_req: ToolCompletionRequest,
) -> Result<ToolCompletionResponse, crate::error::LlmError> {
unimplemented!("stub")
}
}
/// Build a Worker wired to a ToolRegistry containing the given tools.
async fn make_worker(tools: Vec<Arc<dyn Tool>>) -> Worker {
let registry = ToolRegistry::new();
for t in tools {
registry.register(t).await;
}
let cm = Arc::new(crate::context::ContextManager::new(5));
let job_id = cm.create_job("test", "test job").await.unwrap();
let deps = WorkerDeps {
context_manager: cm,
llm: Arc::new(StubLlm),
safety: Arc::new(SafetyLayer::new(&SafetyConfig {
max_output_length: 100_000,
injection_check_enabled: false,
})),
tools: Arc::new(registry),
store: None,
hooks: Arc::new(crate::hooks::HookRegistry::new()),
timeout: Duration::from_secs(30),
use_planning: false,
};
Worker::new(job_id, deps)
}
#[test]
fn test_tool_selection_preserves_call_id() {
let selection = ToolSelection {
@@ -899,4 +1044,119 @@ mod tests {
"The tool returned: TASK_COMPLETE signal"
));
}
#[tokio::test]
async fn test_parallel_speedup() {
// 3 tools each sleeping 200ms should finish in roughly 200ms (parallel),
// not ~600ms (sequential).
let tools: Vec<Arc<dyn Tool>> = (0..3)
.map(|i| {
Arc::new(SlowTool {
tool_name: format!("slow_{}", i),
delay: Duration::from_millis(200),
}) as Arc<dyn Tool>
})
.collect();
let worker = make_worker(tools).await;
let selections: Vec<ToolSelection> = (0..3)
.map(|i| ToolSelection {
tool_name: format!("slow_{}", i),
parameters: serde_json::json!({}),
reasoning: String::new(),
alternatives: vec![],
tool_call_id: format!("call_{}", i),
})
.collect();
let start = std::time::Instant::now();
let results = worker.execute_tools_parallel(&selections).await;
let elapsed = start.elapsed();
assert_eq!(results.len(), 3);
for r in &results {
assert!(r.result.is_ok(), "Tool should succeed");
}
// Parallel should complete well under the sequential 600ms threshold.
assert!(
elapsed < Duration::from_millis(500),
"Parallel execution took {:?}, expected < 500ms",
elapsed
);
}
#[tokio::test]
async fn test_result_ordering_preserved() {
// Tools with different delays finish in different order.
// Results must be returned in the original request order.
let tools: Vec<Arc<dyn Tool>> = vec![
Arc::new(SlowTool {
tool_name: "tool_a".into(),
delay: Duration::from_millis(300),
}),
Arc::new(SlowTool {
tool_name: "tool_b".into(),
delay: Duration::from_millis(100),
}),
Arc::new(SlowTool {
tool_name: "tool_c".into(),
delay: Duration::from_millis(200),
}),
];
let worker = make_worker(tools).await;
let selections = vec![
ToolSelection {
tool_name: "tool_a".into(),
parameters: serde_json::json!({}),
reasoning: String::new(),
alternatives: vec![],
tool_call_id: "call_a".into(),
},
ToolSelection {
tool_name: "tool_b".into(),
parameters: serde_json::json!({}),
reasoning: String::new(),
alternatives: vec![],
tool_call_id: "call_b".into(),
},
ToolSelection {
tool_name: "tool_c".into(),
parameters: serde_json::json!({}),
reasoning: String::new(),
alternatives: vec![],
tool_call_id: "call_c".into(),
},
];
let results = worker.execute_tools_parallel(&selections).await;
// Results must be in same order as selections, not completion order.
assert!(results[0].result.as_ref().unwrap().contains("done_tool_a"));
assert!(results[1].result.as_ref().unwrap().contains("done_tool_b"));
assert!(results[2].result.as_ref().unwrap().contains("done_tool_c"));
}
#[tokio::test]
async fn test_missing_tool_produces_error_not_panic() {
// If a tool doesn't exist, the result slot should contain an error.
let worker = make_worker(vec![]).await;
let selections = vec![ToolSelection {
tool_name: "nonexistent_tool".into(),
parameters: serde_json::json!({}),
reasoning: String::new(),
alternatives: vec![],
tool_call_id: "call_x".into(),
}];
let results = worker.execute_tools_parallel(&selections).await;
assert_eq!(results.len(), 1);
assert!(
results[0].result.is_err(),
"Missing tool should produce an error, not a panic"
);
}
}