Handle invalid NaN values that the osBean returns on Mac sometimes.

PiperOrigin-RevId: 495821759
Change-Id: I831a3386a1fdcf05266b4f6afa9e37eb9693aacf

src/main/java/com/google/devtools/build/lib/profiler/CollectLocalResourceUsage.java

@@ -132,6 +132,12 @@ public void run() {
       long nextCpuTimeNanos = osBean.getProcessCpuTime();
 
       double systemCpuLoad = osBean.getSystemCpuLoad();
+      if (Double.isNaN(systemCpuLoad)) {
+        // Unlike advertised, on Mac the system CPU load is NaN sometimes.
+        // There is no good way to handle this, so to avoid any downstream method crashing on this,
+        // we reset the CPU value here.
+        systemCpuLoad = 0;
+      }
       double systemUsage = systemCpuLoad * numProcessors;
 
       long systemMemoryUsageMb = -1;