fix(scheduler): priority-aware InferenceQueue via container/heap — closes #49 by jpleva91 · Pull Request #103 · AgentGuardHQ/shellforge

jpleva91 · 2026-04-02T05:26:23Z

Summary

Replaces FIFO channel queue with a container/heap-based max-heap ordered by Priority (descending), then by insertion sequence (FIFO tie-breaking within equal priority)
Adds waitEntry with req, grant channel, seq, and index fields; implements heap.Interface via requestHeap
Grants pending slots immediately on release using the heap so higher-priority requests are never blocked behind lower-priority ones

Test plan

Priority ordering: higher-priority requests dispatched before lower-priority
FIFO tie-breaking: equal-priority requests served in insertion order
Concurrency cap: never exceeds MaxParallel simultaneous slots
Queue-full rejection: returns error when MaxQueued exceeded
Context cancellation: cancelled requests are cleanly removed from heap
Release: slot released correctly, unblocks next waiter
MaxParallel zero/negative treated as 1

Closes #49

🤖 Generated with Claude Code

…ture Reposition ShellForge as both a governed agent runtime and an interactive coding CLI. Add shellforge chat (REPL), shellforge ralph (multi-task loop), sub-agent orchestrator, and edit_file/glob/grep tools to README, architecture, and roadmap docs. Mark v0.8.0 UMAAL milestone as completed. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

…oses #49 Replace the FIFO semaphore channel with a max-priority heap so that higher-Priority requests (PriorityEvaluator > PriorityCorrector > PriorityWorker) are granted inference slots before lower-priority ones. Within equal priority, FIFO order is preserved via a monotonic seq counter. Submit() now returns a release func() that the caller MUST invoke once inference completes, correctly extending slot ownership beyond the call. Adds 7 tests: priority ordering, FIFO tie-breaking, concurrency cap, queue-full rejection, context cancellation, release correctness, and MaxParallel accessor. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Copilot

Pull request overview

This PR updates the scheduler package’s InferenceQueue to actually honor request priority when granting limited inference slots, addressing issue #49. It also includes broad documentation updates describing new/renamed CLI entry points and capabilities.

Changes:

Replace the FIFO semaphore-style queue with a container/heap max-heap ordered by request Priority, with FIFO tie-breaking via a monotonic sequence.
Change Submit to return a caller-invoked release() function to free the granted slot, and add tests covering priority/FIFO, depth limiting, cancellation, and release behavior.
Update README and docs to describe chat / ralph entry points, built-in tools, and architecture/roadmap details.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
README.md	Updates product messaging and adds docs for chat/ralph modes and built-in tools.
internal/scheduler/queue.go	Implements a priority-aware heap-based `InferenceQueue` with explicit release semantics.
internal/scheduler/queue_test.go	Adds unit tests for priority ordering, FIFO ties, concurrency cap, queue-full, cancellation, and release.
docs/roadmap.md	Updates roadmap for v0.8.0 feature set and refreshes the “Stack” section.
docs/architecture.md	Documents entry points and expands architecture notes around REPL/ralph/sub-agent orchestration.

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Copilot · 2026-04-02T05:29:13Z

internal/scheduler/queue.go

 func NewInferenceQueue(maxParallel, maxDepth int) *InferenceQueue {
-	return &InferenceQueue{
-		slots:    make(chan struct{}, maxParallel),
-		maxDepth: maxDepth,
+	q := &InferenceQueue{
+		maxParallel: maxParallel,
+		maxDepth:    maxDepth,
 	}
+	heap.Init(&q.waiting)
+	return q


NewInferenceQueue stores maxParallel as-is. If maxParallel is 0 or negative, tryDispatch will never grant any slots (running < maxParallel is always false), causing Submit to block indefinitely. The PR description mentions treating maxParallel <= 0 as 1; please normalize maxParallel to at least 1 (or return an error) when constructing the queue.

Copilot · 2026-04-02T05:29:14Z

internal/scheduler/queue.go

+func (q *InferenceQueue) Submit(ctx context.Context, req InferenceRequest) (func(), error) {
 	if int(atomic.LoadInt64(&q.pending)) >= q.maxDepth {
-		return fmt.Errorf("inference queue full (%d pending)", q.maxDepth)
+		return nil, fmt.Errorf("inference queue full (%d pending)", q.maxDepth)
 	}
 	atomic.AddInt64(&q.pending, 1)
-	defer atomic.AddInt64(&q.pending, -1)



The maxDepth check is not enforced atomically with the increment of pending. With concurrent Submit calls, multiple goroutines can observe pending < maxDepth and then all increment, allowing pending to exceed maxDepth (violating the documented rejection behavior). Consider incrementing first and rolling back when the new value exceeds maxDepth (or use a CAS loop / mutex-protected check+increment) to make the depth limit strict under concurrency.

Copilot · 2026-04-02T05:29:14Z

internal/scheduler/queue.go

+	case <-entry.grant:
+		return func() {
+			atomic.AddInt64(&q.pending, -1)
+			q.mu.Lock()
+			q.running--
+			q.tryDispatch()
+			q.mu.Unlock()
+		}, nil


The returned release() function is not idempotent; calling it twice will decrement q.pending twice and can drive q.running negative, breaking queue invariants and potentially allowing more than maxDepth/maxParallel work. Consider wrapping the body with sync.Once (or an atomic flag) so double-calls are harmless and easier to debug.

Copilot · 2026-04-02T05:29:14Z

internal/scheduler/queue_test.go

+	// Small delay so the low-priority goroutine enters the heap first.
+	time.Sleep(5 * time.Millisecond)
+	go func() {


This test relies on short time.Sleep delays to ensure goroutine scheduling/insertion order. These sleeps can be flaky on slower CI or under high load. Prefer a synchronization point (e.g., a channel/WaitGroup signal from inside Submit after enqueue, or polling q.Pending()/heap length under a deadline) so the test deterministically waits for the low-priority request to be enqueued before submitting the high-priority one.

Copilot · 2026-04-02T05:29:14Z

internal/scheduler/queue_test.go

+
+	for i := 0; i < 3; i++ {
+		i := i
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			release, err := q.Submit(context.Background(), req(PriorityWorker))
+			if err != nil {
+				t.Errorf("submit %d: %v", i, err)
+				return
+			}
+			mu.Lock()
+			order = append(order, i)
+			mu.Unlock()
+			release()
+		}()
+		time.Sleep(2 * time.Millisecond) // ensure ordered insertion
+	}
+	time.Sleep(10 * time.Millisecond)
+


This test uses time.Sleep to "ensure ordered insertion". Sleep-based ordering is inherently non-deterministic and can flake. Consider coordinating insertion order deterministically (e.g., have each goroutine signal when it has enqueued, then release the held slot once all are enqueued) and then assert the completion order.

Suggested change

for i := 0; i < 3; i++ {

i := i

wg.Add(1)

go func() {

defer wg.Done()

release, err := q.Submit(context.Background(), req(PriorityWorker))

if err != nil {

t.Errorf("submit %d: %v", i, err)

return

}

mu.Lock()

order = append(order, i)

mu.Unlock()

release()

}()

time.Sleep(2 * time.Millisecond) // ensure ordered insertion

}

time.Sleep(10 * time.Millisecond)

starts := make([]chan struct{}, 3)

for i := 0; i < 3; i++ {

i := i

start := make(chan struct{})

starts[i] = start

wg.Add(1)

go func(idx int, start <-chan struct{}) {

defer wg.Done()

// Wait until we're explicitly released to submit, to enforce

// a deterministic submission order.

<-start

release, err := q.Submit(context.Background(), req(PriorityWorker))

if err != nil {

t.Errorf("submit %d: %v", idx, err)

return

}

mu.Lock()

order = append(order, idx)

mu.Unlock()

release()

}(i, start)

}

// Release the goroutines to submit in a defined order.

for i := 0; i < 3; i++ {

close(starts[i])

}

Copilot · 2026-04-02T05:29:15Z

README.md

+### 5. Start a chat session
+
+```bash
+shellforge chat                     # interactive REPL — pair-program with a local model
+```
+
+Or run a one-shot agent:

 ```bash
 shellforge agent "describe what this project does"


The PR title/description are focused on making InferenceQueue priority-aware, but this README hunk also introduces/renames major user-facing features (chat REPL, Ralph loop, tool list, entry points). If these doc updates are intended as part of this PR, they should be called out in the PR description; otherwise consider splitting documentation/feature messaging changes into a separate PR to keep scope aligned with the scheduler fix.

jpleva91 and others added 2 commits April 1, 2026 01:49

Copilot AI review requested due to automatic review settings April 2, 2026 05:26

Copilot started reviewing on behalf of jpleva91 April 2, 2026 05:26 View session

Copilot AI reviewed Apr 2, 2026

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fix(scheduler): priority-aware InferenceQueue via container/heap — closes #49#103

fix(scheduler): priority-aware InferenceQueue via container/heap — closes #49#103
jpleva91 wants to merge 2 commits intomainfrom
fix/inference-queue-priority-49

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jpleva91 commented Apr 2, 2026

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