Reduce parallelism in pebble nightly tests

These tests are still flaky even after spliting them into two separate
jobs. This PR tries to solve this issue by reducing the parallelism to
half of the available cores.

Close NIT-4375

Author: gligneul

.github/workflows/_go-tests.yml

@@ -220,11 +220,14 @@ jobs:
           ${{ github.workspace }}/.github/workflows/gotestsum.sh --timeout 90m --test_database_engine pebble
           --junitfile test-results/junit-pebble.xml --run '^Test[A-L]'
 
+      - name: define 
+        if: inputs.run-pebble-b
+
       - name: run pebble tests (B-batch)
         if: inputs.run-pebble-b
         run: >-
           ${{ github.workspace }}/.github/workflows/gotestsum.sh --timeout 90m --test_database_engine pebble
-          --junitfile test-results/junit-pebble.xml --skip '^Test[A-L]'
+          --junitfile test-results/junit-pebble.xml --skip '^Test[A-L]' --parallel  $(( $(nproc) > 2 ? $(nproc) / 2 : 1 ))
 
       # --------------------- PROCESS JUNIT LOGS ---------------------
 

.github/workflows/gotestsum.sh

@@ -19,6 +19,7 @@ race=false
 cover=false
 consensus_execution_in_same_process_use_rpc=false
 flaky=false
+parallel=""
 while [[ $# -gt 0 ]]; do
   case $1 in
     --timeout)
@@ -83,6 +84,9 @@ while [[ $# -gt 0 ]]; do
       flaky=true
       shift
       ;;
+    --parallel)
+      check_missing_value $# "$1" "--parallel"
+      parallel=$1
     *)
       echo "Invalid argument: $1"
       exit 1
@@ -136,6 +140,10 @@ if [ "$cover" == true ]; then
   cmd="$cmd -coverprofile=coverage.txt -covermode=atomic -coverpkg=./...,./go-ethereum/..."
 fi
 
+if [ "$parallel" != "" ]; then
+  cmd="$cmd -parallel $parallel"
+fi
+
 if [ "$test_state_scheme" != "" ]; then
     cmd="$cmd -args -- --test_state_scheme=$test_state_scheme --test_loglevel=8"
 else

changelog/gligneul-nit-4375.md

@@ -0,0 +1,4 @@
+### Ignored
+
+- Reduce parallelism in pebble nightly tests
+