⚡ Bolt: Add concurrent PR status checks

.jules/bolt.md

@@ -0,0 +1,3 @@
+## 2024-05-24 - N+1 GitHub API Calls in Multi-Repo Fan-Out
+**Learning:** `_list_open_prs` does not use concurrent requests but `_filter_to_still_open_prs` issues one `gh pr view` for every PR sequentially. In a multi-repo supervisor run where there might be many PRs open, this sequential list iteration creates a significant N+1 performance bottleneck.
+**Action:** Use `concurrent.futures.ThreadPoolExecutor` to run `_pr_is_still_open` concurrently across PRs to remove the N+1 delay.

ralph_loop/cli.py

@@ -1,7 +1,9 @@
 """Command-line interface and top-level orchestration."""
+
 from __future__ import annotations
 
 import argparse
+import concurrent.futures
 import os
 import re
 import shlex
@@ -335,9 +337,7 @@ def _validate_pr_metadata(
 ) -> str:
     if pr_data.get("state") != "OPEN":
         raise CommandError(
-            "PR {} is not open (state={}).".format(
-                pr_number, pr_data.get("state")
-            )
+            "PR {} is not open (state={}).".format(pr_number, pr_data.get("state"))
         )
     if pr_data.get("isDraft"):
         raise CommandError(
@@ -529,6 +529,13 @@ def _spawn_child(
     return proc, log_path, log_handle
 
 
+def _check_pr_still_open(pr: int) -> Tuple[int, bool, Optional[Exception]]:
+    try:
+        return pr, _pr_is_still_open(pr), None
+    except CommandError as exc:
+        return pr, True, exc
+
+
 def _filter_to_still_open_prs(pr_numbers: List[int]) -> List[int]:
     """Drop PRs that are no longer OPEN/non-draft via a targeted gh pr view.
 
@@ -543,24 +550,31 @@ def _filter_to_still_open_prs(pr_numbers: List[int]) -> List[int]:
     not-OPEN. This matches the behaviour callers expect: do not silently
     swallow stale PRs because of a flaky network.
     """
+    if not pr_numbers:
+        return []
+
     kept: List[int] = []
-    for pr in pr_numbers:
-        try:
-            still_open = _pr_is_still_open(pr)
-        except CommandError as exc:
-            _print_step(
-                "Could not confirm PR #{} open state ({}); keeping it in the "
-                "fan-out set.".format(pr, exc)
-            )
-            kept.append(pr)
-            continue
-        if still_open:
-            kept.append(pr)
-        else:
-            _print_step(
-                "PR #{} is no longer open (per gh pr view); skipping "
-                "fan-out spawn.".format(pr)
-            )
+    # PERFORMANCE OPTIMIZATION:
+    # Use ThreadPoolExecutor to run _pr_is_still_open concurrently instead of sequentially.
+    # This removes an N+1 GitHub API call delay, significantly speeding up PR status checks
+    # during multi-repo fan-out runs when multiple PRs are open.
+    with concurrent.futures.ThreadPoolExecutor(
+        max_workers=min(10, len(pr_numbers))
+    ) as executor:
+        for pr, still_open, exc in executor.map(_check_pr_still_open, pr_numbers):
+            if exc:
+                _print_step(
+                    "Could not confirm PR #{} open state ({}); keeping it in the "
+                    "fan-out set.".format(pr, exc)
+                )
+                kept.append(pr)
+            elif still_open:
+                kept.append(pr)
+            else:
+                _print_step(
+                    "PR #{} is no longer open (per gh pr view); skipping "
+                    "fan-out spawn.".format(pr)
+                )
     return kept
 
 
@@ -605,9 +619,7 @@ def _fan_out_all_prs(
     if args.fan_out_log_dir:
         log_root = os.path.abspath(os.path.expanduser(args.fan_out_log_dir))
     else:
-        log_root = os.path.join(
-            os.path.dirname(script_path), ".ralph-logs", "fan-out"
-        )
+        log_root = os.path.join(os.path.dirname(script_path), ".ralph-logs", "fan-out")
     os.makedirs(log_root, exist_ok=True)
     stuck_timeout = max(60, args.fan_out_stuck_timeout_seconds)
     respawn_backoff = max(1, args.fan_out_respawn_backoff_seconds)
@@ -700,9 +712,7 @@ def _request_reload(_signum, _frame):
                         reason = "ordinary exit"
                     _print_step(
                         "PR #{} loop exited with code {} ({}); respawning after "
-                        "{}s (log: {})".format(
-                            pr, rc, reason, backoff_for_pr, log_path
-                        )
+                        "{}s (log: {})".format(pr, rc, reason, backoff_for_pr, log_path)
                     )
                     try:
                         with open(log_path, "ab", buffering=0) as marker:
@@ -796,15 +806,11 @@ def _request_reload(_signum, _frame):
                 # ordinary-exit and stuck-timeout branches above, which both
                 # rewrite pending_backoff to ``respawn_backoff``.
                 _print_step(
-                    "Respawned PR #{} pid={} (log: {})".format(
-                        pr, proc.pid, log_path
-                    )
+                    "Respawned PR #{} pid={} (log: {})".format(pr, proc.pid, log_path)
                 )
     finally:
         if reload_requested["flag"]:
-            _print_step(
-                "Reload requested via SIGHUP; re-exec'ing supervisor"
-            )
+            _print_step("Reload requested via SIGHUP; re-exec'ing supervisor")
             for pr, (proc, _log_path, log_handle, _spawned_at) in list(
                 children.items()
             ):
@@ -822,9 +828,7 @@ def _request_reload(_signum, _frame):
                 signal.signal(signal.SIGHUP, previous_hup)
             sys.stdout.flush()
             sys.stderr.flush()
-            os.execv(
-                sys.executable, [sys.executable, script_path] + sys.argv[1:]
-            )
+            os.execv(sys.executable, [sys.executable, script_path] + sys.argv[1:])
         for pr, (proc, _log_path, log_handle, _spawned_at) in list(children.items()):
             try:
                 proc.terminate()
@@ -854,9 +858,7 @@ def _request_reload(_signum, _frame):
     return 0
 
 
-def _resolve_target_directories(
-    raw_dirs: List[str], recursive: bool
-) -> List[str]:
+def _resolve_target_directories(raw_dirs: List[str], recursive: bool) -> List[str]:
     """Expand the user-supplied directory args into concrete repo paths.
 
     - If ``recursive`` is set, each input path is treated as a parent and we
@@ -878,9 +880,7 @@ def _push(path: str) -> None:
         path = os.path.abspath(os.path.expanduser(raw))
         if not os.path.isdir(path):
             raise CommandError(
-                "Target directory does not exist or is not a directory: {}".format(
-                    raw
-                )
+                "Target directory does not exist or is not a directory: {}".format(raw)
             )
         if not recursive:
             _push(path)
@@ -933,7 +933,10 @@ def _fan_out_across_directories(
         base_args.append(token)
     procs: List[Tuple[str, subprocess.Popen, str, Any]] = []
     for target_dir in target_dirs:
-        slug = re.sub(r"[^A-Za-z0-9._-]+", "-", os.path.basename(target_dir.rstrip("/"))) or "repo"
+        slug = (
+            re.sub(r"[^A-Za-z0-9._-]+", "-", os.path.basename(target_dir.rstrip("/")))
+            or "repo"
+        )
         log_path = os.path.join(log_root, "{}.log".format(slug))
         log_handle = open(log_path, "ab", buffering=0)
         cmd = [sys.executable, script_path] + base_args + [target_dir]
@@ -1127,9 +1130,7 @@ def _handle_shutdown(signum, _frame):
             )
 
         pr_target = str(pr_number)
-        _print_step(
-            "Using PR #{} {}".format(pr_number, pr_data.get("url", ""))
-        )
+        _print_step("Using PR #{} {}".format(pr_number, pr_data.get("url", "")))
         _mark_pr_needs_review(pr_target)
         if not args.skip_rebase:
             _print_step("Initial rebase before review/fix loop")
@@ -1345,9 +1346,7 @@ def _handle_shutdown(signum, _frame):
 
         if not args.skip_merge:
             fresh_pr_data = _pr_view(str(pr_number))
-            fresh_branch = _validate_pr_metadata(
-                fresh_pr_data, pr_number, args.base
-            )
+            fresh_branch = _validate_pr_metadata(fresh_pr_data, pr_number, args.base)
             if fresh_branch != branch:
                 raise CommandError(
                     "PR #{} head branch changed from '{}' to '{}' during the run.".format(