From cea6834fef54da59fc1692d1db0221b93793238f Mon Sep 17 00:00:00 2001
From: Jacky Zhao <j.zhao2k19@gmail.com>
Date: Wed, 09 Aug 2023 07:26:33 +0000
Subject: [PATCH] profiling, better concurrency heuristics

---
 quartz/processors/parse.ts |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/quartz/processors/parse.ts b/quartz/processors/parse.ts
index 69df69b..299d59a 100644
--- a/quartz/processors/parse.ts
+++ b/quartz/processors/parse.ts
@@ -9,7 +9,6 @@
 import { read } from "to-vfile"
 import { FilePath, QUARTZ, slugifyFilePath } from "../path"
 import path from "path"
-import os from "os"
 import workerpool, { Promise as WorkerPromise } from "workerpool"
 import { QuartzLogger } from "../log"
 import { trace } from "../trace"
@@ -82,6 +81,7 @@
     const res: ProcessedContent[] = []
     for (const fp of fps) {
       try {
+        const perf = new PerfTimer()
         const file = await read(fp)
 
         // strip leading and trailing whitespace
@@ -101,7 +101,7 @@
         res.push([newAst, file])
 
         if (argv.verbose) {
-          console.log(`[process] ${fp} -> ${file.data.slug}`)
+          console.log(`[process] ${fp} -> ${file.data.slug} (${perf.timeSince()})`)
         }
       } catch (err) {
         trace(`\nFailed to process \`${fp}\``, err as Error)
@@ -112,14 +112,15 @@
   }
 }
 
+const clamp = (num: number, min: number, max: number) => Math.min(Math.max(Math.round(num), min), max);
 export async function parseMarkdown(ctx: BuildCtx, fps: FilePath[]): Promise<ProcessedContent[]> {
   const { argv } = ctx
   const perf = new PerfTimer()
   const log = new QuartzLogger(argv.verbose)
 
+  // rough heuristics: 128 gives enough time for v8 to JIT and optimize parsing code paths
   const CHUNK_SIZE = 128
-  let concurrency =
-    ctx.argv.concurrency ?? (fps.length < CHUNK_SIZE ? 1 : os.availableParallelism())
+  const concurrency = ctx.argv.concurrency ?? clamp(fps.length / CHUNK_SIZE, 1, 4)
 
   let res: ProcessedContent[] = []
   log.start(`Parsing input files using ${concurrency} threads`)

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