feat(global-options): Default concurrency to logical CPU count (#1931)

lerna · Feb 14, 2019 · 2c487fe · 2c487fe
1 parent a6733a2
commit 2c487fe
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Showing 4 changed files with 12 additions and 5 deletions.
diff --git a/core/command/__tests__/command.test.js b/core/command/__tests__/command.test.js
@@ -9,6 +9,10 @@ const tempy = require("tempy");
 
 // partially mocked
 const ChildProcessUtilities = require("@lerna/child-process");
+const os = require("os");
+
+// normalize concurrency across different environments (localhost, CI, etc)
+jest.spyOn(os, "cpus").mockImplementation(() => new Array(42));
 
 // helpers
 const initFixture = require("@lerna-test/init-fixture")(__dirname);
@@ -70,14 +74,14 @@ describe("core-command", () => {
       const command = testFactory({ concurrency: "bla" });
       await command;
 
-      expect(command.concurrency).toBe(4);
+      expect(command.concurrency).toBe(42);
     });
 
     it("should fall back to default if concurrency given is 0", async () => {
       const command = testFactory({ concurrency: 0 });
       await command;
 
-      expect(command.concurrency).toBe(4);
+      expect(command.concurrency).toBe(42);
     });
 
     it("should fall back to 1 if concurrency given is smaller than 1", async () => {

diff --git a/core/command/index.js b/core/command/index.js
@@ -4,6 +4,7 @@ const _ = require("lodash");
 const dedent = require("dedent");
 const execa = require("execa");
 const log = require("npmlog");
+const os = require("os");
 
 const PackageGraph = require("@lerna/package-graph");
 const Project = require("@lerna/project");
@@ -14,7 +15,7 @@ const cleanStack = require("./lib/clean-stack");
 const logPackageError = require("./lib/log-package-error");
 const warnIfHanging = require("./lib/warn-if-hanging");
 
-const DEFAULT_CONCURRENCY = 4;
+const DEFAULT_CONCURRENCY = os.cpus().length;
 
 class Command {
   constructor(argv) {

diff --git a/core/global-options/README.md b/core/global-options/README.md
@@ -6,7 +6,7 @@
 
 ### `--concurrency`
 
-How many threads to use when Lerna parallelizes the tasks (defaults to `4`)
+How many threads to use when Lerna parallelizes the tasks (defaults to count of logical CPU cores)
 
 ```sh
 $ lerna publish --concurrency 1

diff --git a/core/global-options/index.js b/core/global-options/index.js
@@ -1,5 +1,7 @@
 "use strict";
 
+const os = require("os");
+
 module.exports = globalOptions;
 
 function globalOptions(yargs) {
@@ -11,7 +13,7 @@ function globalOptions(yargs) {
       type: "string",
     },
     concurrency: {
-      defaultDescription: "4",
+      defaultDescription: os.cpus().length,
       describe: "How many processes to use when lerna parallelizes tasks.",
       type: "number",
       requiresArg: true,