Feat: add basic parallel support for listing packages

nixpkgs_review/cli/__init__.py

@@ -250,10 +250,10 @@ def common_flags() -> list[CommonFlag]:
             help="Extra nixpkgs config to pass to `import <nixpkgs>`",
         ),
         CommonFlag(
-            "--num-procs-eval",
+            "--num-parallel-evals",
             type=int,
             default=1,
-            help="Number of parallel `nix-env` processes to run simultaneously (warning, can imply heavy RAM usage)",
+            help="Number of parallel `nix-env`/`nix eval` processes to run simultaneously (warning, can imply heavy RAM usage)",
         ),
     ]
 

nixpkgs_review/cli/pr.py

@@ -86,7 +86,7 @@ def pr_command(args: argparse.Namespace) -> str:
                     build_graph=args.build_graph,
                     nixpkgs_config=nixpkgs_config,
                     extra_nixpkgs_config=args.extra_nixpkgs_config,
-                    n_procs_eval=args.num_procs_eval,
+                    num_parallel_evals=args.num_parallel_evals,
                 )
                 contexts.append((pr, builddir.path, review.build_pr(pr)))
             except NixpkgsReviewError as e:

nixpkgs_review/nix.py

@@ -1,11 +1,10 @@
+import concurrent.futures
 import json
-import multiprocessing as mp
 import os
 import shlex
 import shutil
 import subprocess
 from dataclasses import dataclass, field
-from functools import partial
 from pathlib import Path
 from sys import platform
 from tempfile import NamedTemporaryFile
@@ -271,32 +270,29 @@ def nix_eval(
             os.unlink(attr_json.name)
 
 
-def nix_eval_thread(
-    system: System,
-    attr_names: set[str],
-    allow: AllowedFeatures,
-    nix_path: str,
-) -> tuple[System, list[Attr]]:
-    return system, nix_eval(attr_names, system, allow, nix_path)
-
-
 def multi_system_eval(
     attr_names_per_system: dict[System, set[str]],
     allow: AllowedFeatures,
     nix_path: str,
-    n_procs: int,
+    n_threads: int,
 ) -> dict[System, list[Attr]]:
-    nix_eval_partial = partial(
-        nix_eval_thread,
-        allow=allow,
-        nix_path=nix_path,
-    )
-
-    args: list[tuple[System, set[str]]] = list(attr_names_per_system.items())
-    with mp.Pool(n_procs) as pool:
-        results: list[tuple[System, list[Attr]]] = pool.starmap(nix_eval_partial, args)
-
-    return {system: attrs for system, attrs in results}
+    results: dict[System, list[Attr]] = {}
+    with concurrent.futures.ThreadPoolExecutor(max_workers=n_threads) as executor:
+        future_to_system = {
+            executor.submit(
+                nix_eval,
+                attrs=attrs,
+                system=system,
+                allow=allow,
+                nix_path=nix_path,
+            ): system
+            for system, attrs in attr_names_per_system.items()
+        }
+        for future in concurrent.futures.as_completed(future_to_system):
+            system = future_to_system[future]
+            results[system] = future.result()
+
+    return results
 
 
 def nix_build(
@@ -309,7 +305,7 @@ def nix_build(
     build_graph: str,
     nix_path: str,
     nixpkgs_config: Path,
-    n_procs_eval: int,
+    n_threads: int,
 ) -> dict[System, list[Attr]]:
     if not attr_names_per_system:
         info("Nothing to be built.")
@@ -319,7 +315,7 @@ def nix_build(
         attr_names_per_system,
         allow,
         nix_path,
-        n_procs=n_procs_eval,
+        n_threads=n_threads,
     )
 
     filtered_per_system: dict[System, list[str]] = {}

nixpkgs_review/review.py

@@ -1,4 +1,5 @@
 import argparse
+import concurrent.futures
 import os
 import subprocess
 import sys
@@ -107,7 +108,7 @@ def __init__(
         skip_packages_regex: list[Pattern[str]] = [],
         checkout: CheckoutOption = CheckoutOption.MERGE,
         sandbox: bool = False,
-        n_procs_eval: int = 1,
+        num_parallel_evals: int = 1,
     ) -> None:
         self.builddir = builddir
         self.build_args = build_args
@@ -140,7 +141,7 @@ def __init__(
         self.build_graph = build_graph
         self.nixpkgs_config = nixpkgs_config
         self.extra_nixpkgs_config = extra_nixpkgs_config
-        self.n_procs_eval = n_procs_eval
+        self.num_parallel_evals = num_parallel_evals
 
     def worktree_dir(self) -> str:
         return str(self.builddir.worktree_dir)
@@ -181,36 +182,26 @@ def build_commit(
         self.git_worktree(base_commit)
 
         # TODO: nix-eval-jobs ?
-        # parallel version: returning a dict[System, list[Package]]
-        # base_packages = list_packages(
-        #     self.builddir.nix_path,
-        #     self.systems,
-        #     self.allow,
-        # )
-        base_packages = {
-            system: list_packages(
-                self.builddir.nix_path,
-                system,
-                self.allow,
-            )
-            for system in self.systems
-        }
+        base_packages: dict[System, list[Package]] = list_packages(
+            self.builddir.nix_path,
+            self.systems,
+            self.allow,
+            n_threads=self.num_parallel_evals,
+        )
 
         if reviewed_commit is None:
             self.apply_unstaged(staged)
         else:
             self.git_merge(reviewed_commit)
 
         # TODO: nix-eval-jobs ?
-        merged_packages = {
-            system: list_packages(
-                self.builddir.nix_path,
-                system,
-                self.allow,
-                check_meta=True,
-            )
-            for system in self.systems
-        }
+        merged_packages: dict[System, list[Package]] = list_packages(
+            self.builddir.nix_path,
+            self.systems,
+            self.allow,
+            n_threads=self.num_parallel_evals,
+            check_meta=True,
+        )
 
         # Systems ordered correctly (x86_64-linux, aarch64-linux, x86_64-darwin, aarch64-darwin)
         sorted_systems: list[System] = sorted(
@@ -268,7 +259,7 @@ def build(
             self.build_graph,
             self.builddir.nix_path,
             self.nixpkgs_config,
-            self.n_procs_eval,
+            self.num_parallel_evals,
         )
 
     def build_pr(self, pr_number: int) -> dict[System, list[Attr]]:
@@ -419,9 +410,9 @@ def parse_packages_xml(stdout: IO[str]) -> list[Package]:
     return packages
 
 
-def list_packages(
+def _list_packages_system(
+    system: System,
     nix_path: str,
-    system: str,
     allow: AllowedFeatures,
     check_meta: bool = False,
 ) -> list[Package]:
@@ -458,6 +449,32 @@ def list_packages(
             return parse_packages_xml(f)
 
 
+def list_packages(
+    nix_path: str,
+    systems: set[System],
+    allow: AllowedFeatures,
+    n_threads: int,
+    check_meta: bool = False,
+) -> dict[System, list[Package]]:
+    results: dict[System, list[Package]] = {}
+    with concurrent.futures.ThreadPoolExecutor(max_workers=n_threads) as executor:
+        future_to_system = {
+            executor.submit(
+                _list_packages_system,
+                system=system,
+                nix_path=nix_path,
+                allow=allow,
+                check_meta=check_meta,
+            ): system
+            for system in systems
+        }
+        for future in concurrent.futures.as_completed(future_to_system):
+            system = future_to_system[future]
+            results[system] = future.result()
+
+    return results
+
+
 def package_attrs(
     package_set: set[str],
     system: str,
@@ -633,7 +650,7 @@ def review_local_revision(
             build_graph=args.build_graph,
             nixpkgs_config=nixpkgs_config,
             extra_nixpkgs_config=args.extra_nixpkgs_config,
-            n_procs_eval=args.num_procs_eval,
+            num_parallel_evals=args.num_parallel_evals,
         )
         review.review_commit(builddir.path, args.branch, commit, staged, print_result)
         return builddir.path