Runtime.availableProcessors() gives info about available resources, not affinity which occurs at scheduling level

java-cpu-affinity-unaware.sh

#!/bin/sh

cat > PrintAvailableProcs.java <<EOF
public class PrintAvailableProcs {
  public static void main(String[] args) {
    System.out.println(Runtime.getRuntime().availableProcessors());
  }
}
EOF
javac PrintAvailableProcs.java

echo "cpuinfo: $(grep -c processor /proc/cpuinfo)"
echo "java: $(java PrintAvailableProcs)"
echo "bound with taskset: $(taskset -c 0 java PrintAvailableProcs)"
echo "bound with numactl: $(numactl -C 0 java PrintAvailableProcs)"