[CI] Allow explicitly override of worker count in run gradle script (e…

…lastic#118734)

This makes running experiments on ci way easier without changing default
behaviour

.ci/scripts/run-gradle.sh

@@ -5,35 +5,39 @@ mkdir -p ~/.gradle/init.d && cp -v $WORKSPACE/.ci/init.gradle ~/.gradle/init.d
 
 MAX_WORKERS=4
 
-# Don't run this stuff on Windows
-if ! uname -a | grep -q MING; then
-  # drop page cache and kernel slab objects on linux
-  [[ -x /usr/local/sbin/drop-caches ]] && sudo /usr/local/sbin/drop-caches
+if [ -z "$MAX_WORKER_ENV" ]; then
+    # Don't run this stuff on Windows
+    if ! uname -a | grep -q MING; then
+      # drop page cache and kernel slab objects on linux
+      [[ -x /usr/local/sbin/drop-caches ]] && sudo /usr/local/sbin/drop-caches
 
-  if [ "$(uname -m)" = "arm64" ] || [ "$(uname -m)" = "aarch64" ]; then
-    MAX_WORKERS=16
-  elif [ -f /proc/cpuinfo ]; then
-    MAX_WORKERS=`grep '^cpu\scores' /proc/cpuinfo  | uniq | sed 's/\s\+//g' |  cut -d':' -f 2`
-  else
-    if [[ "$OSTYPE" == "darwin"* ]]; then
-        MAX_WORKERS=`sysctl -n hw.physicalcpu | sed 's/\s\+//g'`
-    else
-        echo "Unsupported OS Type: $OSTYPE"
-        exit 1
-    fi
-  fi
-  if pwd | grep -v -q ^/dev/shm ; then
-    echo "Not running on a ramdisk, reducing number of workers"
-    MAX_WORKERS=$(($MAX_WORKERS*2/3))
-  fi
+      if [ "$(uname -m)" = "arm64" ] || [ "$(uname -m)" = "aarch64" ]; then
+        MAX_WORKERS=16
+      elif [ -f /proc/cpuinfo ]; then
+        MAX_WORKERS=`grep '^cpu\scores' /proc/cpuinfo  | uniq | sed 's/\s\+//g' |  cut -d':' -f 2`
+      else
+        if [[ "$OSTYPE" == "darwin"* ]]; then
+            MAX_WORKERS=`sysctl -n hw.physicalcpu | sed 's/\s\+//g'`
+        else
+            echo "Unsupported OS Type: $OSTYPE"
+            exit 1
+        fi
+      fi
+      if pwd | grep -v -q ^/dev/shm ; then
+        echo "Not running on a ramdisk, reducing number of workers"
+        MAX_WORKERS=$(($MAX_WORKERS*2/3))
+      fi
 
-  # Export glibc version as environment variable since some BWC tests are incompatible with later versions
-  export GLIBC_VERSION=$(ldd --version | grep '^ldd' | sed 's/.* \([1-9]\.[0-9]*\).*/\1/')
-fi
+      # Export glibc version as environment variable since some BWC tests are incompatible with later versions
+      export GLIBC_VERSION=$(ldd --version | grep '^ldd' | sed 's/.* \([1-9]\.[0-9]*\).*/\1/')
+    fi
 
-# Running on 2-core machines without ramdisk can make this value be 0
-if [[ "$MAX_WORKERS" == "0" ]]; then
-  MAX_WORKERS=1
+    # Running on 2-core machines without ramdisk can make this value be 0
+    if [[ "$MAX_WORKERS" == "0" ]]; then
+      MAX_WORKERS=1
+    fi
+else
+    MAX_WORKERS=$MAX_WORKER_ENV
 fi
 
 set -e