Informational 15 Bitcoin Committed Feb 24, 2026 · 01:24 UTC

CI: use nproc + 1 for pytest parallelism..

77251ec1 View source ↗

Public commit record

What the developer wrote

Authored by Rusty Russell

90/100 · Strong

CI: use nproc + 1 for pytest parallelism..

More future proof, better for self-hosted runners.

Example run times before:

4s CI completion
2m 36s Check we can downgrade the node (compile-gcc, sqlite3, liquid-regtest)
2m 52s Check we can downgrade the node (compile-gcc, postgres, regtest)
3m 20s Check we can downgrade the node (compile-gcc, sqlite3, regtest, 1)
3m 20s Check we can downgrade the node (compile-gcc, sqlite3, regtest, 1)
8m 1s Run fuzz regression tests
11m 46s Run unit tests (compile-clang-sanitizers, 0)
12m 59s Compile CLN compile-gcc
13m 42s Compile CLN compile-clang
14m 10s Compile CLN compile-gcc-O3
14m 15s Compile CLN compile-clang-sanitizers
15m 23s Pre-build checks
19m 37s Test CLN dual-fund
26m 49s Run unit tests (compile-gcc, 1)
43m 19s Valgrind Test CLN Valgrind (06/10)
43m 21s Valgrind Test CLN Valgrind (08/10)
43m 40s Valgrind Test CLN Valgrind (05/10)
43m 59s Valgrind Test CLN Valgrind (03/10)
44m 4s Valgrind Test CLN Valgrind (07/10)
47m 28s Valgrind Test CLN Valgrind (09/10)
47m 37s Valgrind Test CLN Valgrind (02/10)
47m 45s Valgrind Test CLN Valgrind (01/10)
52m 51s Valgrind Test CLN Valgrind (04/10)
54m 6s Valgrind Test CLN Valgrind (10/10)
1h 14m 13s Sanitizers Test CLN (ASan/UBSan (03/12), 3, --test-group=3 --test-group-count=12)
1h 14m 6s Sanitizers Test CLN (ASan/UBSan (06/12), 6, --test-group=6 --test-group-count=12)
1h 15m 23s Sanitizers Test CLN (ASan/UBSan (01/12), 1, --test-group=1 --test-group-count=12)
1h 20m 30s Sanitizers Test CLN (ASan/UBSan (08/12), 8, --test-group=8 --test-group-count=12)
1h 22m 35s Sanitizers Test CLN (ASan/UBSan (12/12), 12, --test-group=12 --test-group-count=12)
1h 23m 49s Sanitizers Test CLN (ASan/UBSan (04/12), 4, --test-group=4 --test-group-count=12)
1h 26m 11s Sanitizers Test CLN (ASan/UBSan (07/12), 7, --test-group=7 --test-group-count=12)
1h 28m 44s Sanitizers Test CLN (ASan/UBSan (05/12), 5, --test-group=5 --test-group-count=12)
1h 29m 1s Sanitizers Test CLN (ASan/UBSan (02/12), 2, --test-group=2 --test-group-count=12)
1h 29m 4s Sanitizers Test CLN (ASan/UBSan (11/12), 11, --test-group=11 --test-group-count=12)
1h 31m 36s Sanitizers Test CLN (ASan/UBSan (09/12), 9, --test-group=9 --test-group-count=12)
1h 38m 54s Sanitizers Test CLN (ASan/UBSan (10/12), 10, --test-group=10 --test-group-count=12)
1h 39m 22s Test CLN liquid
1h 52m 23s Test minimum supported BTC v25.0 with clang
1h 52m 28s Test CLN gcc
1h 53m 57s Test CLN splicing
1h 57m 25s Test CLN postgres
1h 59m 25s Test CLN clang

2d 17h 56m 16s TOTAL

Example runtimes afterwards:

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

✓ Descriptive subject✓ Names a concrete action or component✓ Uses a recognizable type or scope✓ Provides detailed explanatory context✓ Mentions testing or verification

The short version

What changed, and why it matters

This commit only changes how many parallel test jobs run in the project's automated continuous integration (CI) system. It replaces hard-coded numbers like 4 or 2 with a dynamic value based on the number of available CPU cores. There is no change to the Core Lightning node software itself, its network behavior, wallet handling, or any user-facing feature. It is purely an infrastructure speed-up.

Recommended action

No security action needed. This is a normal CI optimization. Reviewers may optionally verify that the increased parallelism does not cause resource contention or flaky tests, but that is a reliability concern, not a security one.

Security signals we found

No strong security signals were identified.

Technical analysis

Evidence from the diff

The patch modifies .github/workflows/ci.yaml. It removes the PYTEST_PAR environment variable and changes pytest -n ${PYTEST_PAR} invocations to pytest -n $(($(nproc) + 1)). It also adds -j $(nproc) to one make check-source invocation and changes one make -j $(nproc) to -j $(($(nproc) + 1)). These are build/test throughput tuning changes in GitHub Actions. No application code, cryptographic operations, protocol handling, or privilege boundaries are affected.

Changed components

.github/workflows/ci.yaml

Inspect captured patch +7 / −13

diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index b9a93a23..f566806a 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -93,7 +93,7 @@ jobs:
           VALGRIND: 0
           PYTEST_OPTS: ${{ env.PYTEST_OPTS_BASE }}
         run: |
-          uv run make check-source BASE_REF="origin/${{ github.base_ref }}"
+          uv run make -j $(nproc) check-source BASE_REF="origin/${{ github.base_ref }}"
       - name: Upload test results
         if: always()
         uses: actions/upload-artifact@v4
@@ -312,7 +312,6 @@ jobs:
       - name: Test
         env:
           SLOW_MACHINE: 1
-          PYTEST_PAR: 4
           TEST_DEBUG: 1
           TEST_DB_PROVIDER: ${{ matrix.TEST_DB_PROVIDER }}
           TEST_NETWORK: ${{ matrix.TEST_NETWORK }}
@@ -323,7 +322,7 @@ jobs:
         run: |
           env
           cat config.vars
-          sg wireshark "uv run eatmydata pytest tests/test_downgrade.py -n ${PYTEST_PAR} ${PYTEST_OPTS}"
+          sg wireshark "uv run eatmydata pytest tests/test_downgrade.py -n $(($(nproc) + 1)) ${PYTEST_OPTS}"
       - name: Upload test results
         if: always()
         uses: actions/upload-artifact@v4
@@ -430,7 +429,6 @@ jobs:
           COMPAT: 1
           CFG: ${{ matrix.CFG }}
           SLOW_MACHINE: 1
-          PYTEST_PAR: 4
           TEST_DEBUG: 1
           TEST_DB_PROVIDER: ${{ matrix.TEST_DB_PROVIDER }}
           TEST_NETWORK: ${{ matrix.TEST_NETWORK }}
@@ -438,7 +436,7 @@ jobs:
         run: |
           env
           cat config.vars
-          VALGRIND=0 sg wireshark "uv run eatmydata pytest tests/ -n ${PYTEST_PAR} ${PYTEST_OPTS}"
+          VALGRIND=0 sg wireshark "uv run eatmydata pytest tests/ -n $(($(nproc) + 1)) ${PYTEST_OPTS}"
       - name: Upload test results
         if: always()
         uses: actions/upload-artifact@v4
@@ -524,9 +522,8 @@ jobs:
         env:
           SLOW_MACHINE: 1
           TEST_DEBUG: 1
-          PYTEST_PAR: 2
         run: |
-          VALGRIND=1 sg wireshark "uv run eatmydata pytest tests/ -n ${PYTEST_PAR} ${PYTEST_OPTS}  ${{ matrix.PYTEST_OPTS }}"
+          VALGRIND=1 sg wireshark "uv run eatmydata pytest tests/ -n $(($(nproc) + 1)) ${PYTEST_OPTS}  ${{ matrix.PYTEST_OPTS }}"
       - name: Upload test results
         if: always()
         uses: actions/upload-artifact@v4
@@ -614,10 +611,8 @@ jobs:
         run: tar -xvjf cln-compile-clang-sanitizers.tar.bz2
 
       - name: Test
-        env:
-          PYTEST_PAR: 2
         run: |
-          sg wireshark "uv run eatmydata pytest tests/ -n ${PYTEST_PAR} ${PYTEST_OPTS}  ${{ matrix.PYTEST_OPTS }}"
+          sg wireshark "uv run eatmydata pytest tests/ -n $(($(nproc) + 1)) ${PYTEST_OPTS}  ${{ matrix.PYTEST_OPTS }}"
       - name: Upload test results
         if: always()
         uses: actions/upload-artifact@v4
@@ -667,7 +662,7 @@ jobs:
           tar -xaf cln-compile-gcc.tar.bz2
       - name: Test
         run: |
-          uv run eatmydata make -j $(nproc) check-doc-examples
+          uv run eatmydata make -j $(($(nproc) + 1)) check-doc-examples
       - name: Upload test results
         if: always()
         uses: actions/upload-artifact@v4
@@ -740,7 +735,6 @@ jobs:
           COMPAT: 1
           CFG: ${{ matrix.CFG }}
           SLOW_MACHINE: 1
-          PYTEST_PAR: 4
           TEST_DEBUG: 1
           TEST_DB_PROVIDER: ${{ matrix.TEST_DB_PROVIDER }}
           TEST_NETWORK: ${{ matrix.TEST_NETWORK }}
@@ -748,7 +742,7 @@ jobs:
         run: |
           env
           cat config.vars
-          VALGRIND=0 sg wireshark "uv run eatmydata pytest tests/ -n ${PYTEST_PAR} ${PYTEST_OPTS}"
+          VALGRIND=0 sg wireshark "uv run eatmydata pytest tests/ -n $(($(nproc) + 1)) ${PYTEST_OPTS}"
       - name: Upload test results
         if: always()
         uses: actions/upload-artifact@v4

Risk score

Why this scored 15/100

Our methodology →

Potential impact 0/30

Exploitability 0/25

Stealth signal 0/15

Affected reach 0/15

Confidence 10/10

Evidence quality 5/5

Human-validated context

Community notes

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No validated notes yet.

The AI analysis stands alone for now. Submit a note if you can add evidence or important context.

What the developer wrote

What changed, and why it matters

Security signals we found

Evidence from the diff

Changed components

Why this scored 15/100

Community notes

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