Use singleton Chrome instance to convert into PDF

CHANGELOG.md

@@ -6,6 +6,10 @@
 
 - Add `--watch` (`-w`) option to support watch mode ([#18](https://github.com/marp-team/marp-cli/pull/18))
 
+### Fixed
+
+- Use singleton Chrome instance to convert into PDF ([#19](https://github.com/marp-team/marp-cli/pull/19))
+
 ## v0.0.8 - 2018-09-15
 
 ### Added

src/converter.ts

@@ -112,9 +112,9 @@ export class Converter {
 
     try {
       const browser = await Converter.runBrowser()
+      const page = await browser.newPage()
 
       try {
-        const page = await browser.newPage()
         await page.goto(uri, {
           waitUntil: ['domcontentloaded', 'networkidle0'],
         })
@@ -124,13 +124,19 @@ export class Converter {
           preferCSSPageSize: true,
         })
       } finally {
-        await browser.close()
+        await page.close()
       }
     } finally {
       if (tmpFile) await tmpFile.cleanup()
     }
   }
 
+  static async closeBrowser() {
+    if (Converter.browser) await Converter.browser.close()
+  }
+
+  private static browser?: puppeteer.Browser
+
   private generateEngine(mergeOptions: MarpitOptions) {
     const { html, options } = this.options
     const opts: any = { ...options, ...mergeOptions }
@@ -149,18 +155,25 @@ export class Converter {
     return engine
   }
 
-  private static runBrowser() {
-    const args: string[] = []
-    const finder: () => string[] = require('is-wsl')
-      ? chromeFinder.wsl
-      : chromeFinder[process.platform]
+  private static async runBrowser() {
+    if (!Converter.browser) {
+      const args: string[] = []
+      const finder: () => string[] = require('is-wsl')
+        ? chromeFinder.wsl
+        : chromeFinder[process.platform]
 
-    if (process.env.IS_DOCKER)
-      args.push('--no-sandbox', '--disable-dev-shm-usage')
+      if (process.env.IS_DOCKER)
+        args.push('--no-sandbox', '--disable-dev-shm-usage')
 
-    return puppeteer.launch({
-      args,
-      executablePath: finder ? finder()[0] : undefined,
-    })
+      Converter.browser = await puppeteer.launch({
+        args,
+        executablePath: finder ? finder()[0] : undefined,
+      })
+
+      Converter.browser.once('disconnected', () => {
+        Converter.browser = undefined
+      })
+    }
+    return Converter.browser
   }
 }

src/marp-cli.ts

@@ -176,5 +176,7 @@ export default async function(argv: string[] = []): Promise<number> {
 
     cli.error(e.message)
     return e.errorCode
+  } finally {
+    await Converter.closeBrowser()
   }
 }

test/converter.ts

@@ -10,6 +10,7 @@ import { CLIError } from '../src/error'
 
 jest.mock('fs')
 
+afterAll(() => Converter.closeBrowser())
 afterEach(() => jest.restoreAllMocks())
 
 describe('Converter', () => {