use already read cpus variable only once and improve code little usi… (#10842)

Author: sktguha

packages/jest-config/src/getMaxWorkers.ts

@@ -22,7 +22,8 @@ export default function getMaxWorkers(
     return parseWorkers(defaultOptions.maxWorkers);
   } else {
     // In watch mode, Jest should be unobtrusive and not use all available CPUs.
-    const numCpus = cpus() ? cpus().length : 1;
+    const cpusInfo = cpus();
+    const numCpus = cpusInfo?.length ?? 1;
     const isWatchModeEnabled = argv.watch || argv.watchAll;
     return Math.max(
       isWatchModeEnabled ? Math.floor(numCpus / 2) : numCpus - 1,
@@ -42,7 +43,7 @@ const parseWorkers = (maxWorkers: string | number): number => {
   ) {
     const numCpus = cpus().length;
     const workers = Math.floor((parsed / 100) * numCpus);
-    return workers >= 1 ? workers : 1;
+    return Math.max(workers, 1);
   }
 
   return parsed > 0 ? parsed : 1;