From dcaf22b32983387e14b931d9c9378a0dbd3a9eae Mon Sep 17 00:00:00 2001
From: Michael Mayer <michael@lastzero.net>
Date: Sat, 9 Jan 2021 12:18:59 +0100
Subject: [PATCH] Config: Detect physical CPU cores to limit number of workers

---
 go.mod                      |  1 +
 go.sum                      |  3 +++
 internal/commands/config.go |  2 +-
 internal/config/config.go   | 15 ++++++++++-----
 internal/config/flags.go    |  4 +++-
 5 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/go.mod b/go.mod
index efbb89e55..226d94ff6 100644
--- a/go.mod
+++ b/go.mod
@@ -29,6 +29,7 @@ require (
 	github.com/json-iterator/go v1.1.10 // indirect
 	github.com/kardianos/osext v0.0.0-20190222173326-2bc1f35cddc0 // indirect
 	github.com/karrick/godirwalk v1.16.1
+	github.com/klauspost/cpuid/v2 v2.0.3
 	github.com/leandro-lugaresi/hub v1.1.1
 	github.com/leonelquinteros/gotext v1.4.0
 	github.com/lib/pq v1.3.0 // indirect
diff --git a/go.sum b/go.sum
index c77ff80cc..60a3bd84e 100644
--- a/go.sum
+++ b/go.sum
@@ -191,6 +191,9 @@ github.com/kardianos/osext v0.0.0-20190222173326-2bc1f35cddc0/go.mod h1:1NbS8ALr
 github.com/karrick/godirwalk v1.16.1 h1:DynhcF+bztK8gooS0+NDJFrdNZjJ3gzVzC545UNA9iw=
 github.com/karrick/godirwalk v1.16.1/go.mod h1:j4mkqPuvaLI8mp1DroR3P6ad7cyYd4c1qeJ3RV7ULlk=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
+github.com/klauspost/cpuid v1.3.1 h1:5JNjFYYQrZeKRJ0734q51WCEEn2huer72Dc7K+R/b6s=
+github.com/klauspost/cpuid/v2 v2.0.3 h1:DNljyrHyxlkk8139OXIAAauCwV8eQGDD6Z8YqnDXdZw=
+github.com/klauspost/cpuid/v2 v2.0.3/go.mod h1:FInQzS24/EEf25PyTYn52gqo7WaD8xa0213Md/qVLRg=
 github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
diff --git a/internal/commands/config.go b/internal/commands/config.go
index 23d20b8b4..9647a0fbe 100644
--- a/internal/commands/config.go
+++ b/internal/commands/config.go
@@ -55,7 +55,7 @@ func configAction(ctx *cli.Context) error {
 	fmt.Printf("%-25s %s\n", "img-path", conf.ImgPath())
 	fmt.Printf("%-25s %s\n", "templates-path", conf.TemplatesPath())
 
-	// Workers.
+	// Background workers.
 	fmt.Printf("%-25s %d\n", "workers", conf.Workers())
 	fmt.Printf("%-25s %d\n", "wakeup-interval", conf.WakeupInterval()/time.Second)
 	fmt.Printf("%-25s %d\n", "auto-index", conf.AutoIndex()/time.Second)
diff --git a/internal/config/config.go b/internal/config/config.go
index a797766fb..c45b1061d 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -20,6 +20,7 @@ import (
 	"github.com/jinzhu/gorm"
 	_ "github.com/jinzhu/gorm/dialects/mysql"
 	_ "github.com/jinzhu/gorm/dialects/sqlite"
+	"github.com/klauspost/cpuid/v2"
 	"github.com/photoprism/photoprism/internal/event"
 	"github.com/photoprism/photoprism/internal/hub"
 	"github.com/photoprism/photoprism/internal/hub/places"
@@ -133,6 +134,10 @@ func (c *Config) Init() error {
 		fs.IgnoreCase()
 	}
 
+	if cpuName := cpuid.CPU.BrandName; cpuName != "" {
+		log.Debugf("config: running on %s", txt.Quote(cpuid.CPU.BrandName))
+	}
+
 	c.initSettings()
 	c.initHub()
 
@@ -328,19 +333,19 @@ func (c *Config) Shutdown() {
 
 // Workers returns the number of workers e.g. for indexing files.
 func (c *Config) Workers() int {
-	numCPU := runtime.NumCPU()
+	cores := cpuid.CPU.PhysicalCores
 
 	// Limit number of workers when using SQLite to avoid database locking issues.
-	if c.DatabaseDriver() == SQLite && numCPU >= 8 && c.options.Workers <= 0 {
+	if c.DatabaseDriver() == SQLite && cores >= 8 && c.options.Workers <= 0 || c.options.Workers > 4 {
 		return 4
 	}
 
-	if c.options.Workers > 0 && c.options.Workers <= numCPU {
+	if c.options.Workers > 0 && c.options.Workers <= runtime.NumCPU() {
 		return c.options.Workers
 	}
 
-	if numCPU > 1 {
-		return numCPU / 2
+	if cores > 1 {
+		return cores / 2
 	}
 
 	return 1
diff --git a/internal/config/flags.go b/internal/config/flags.go
index 1f9044418..ae9a38d7c 100644
--- a/internal/config/flags.go
+++ b/internal/config/flags.go
@@ -1,6 +1,7 @@
 package config
 
 import (
+	"github.com/klauspost/cpuid/v2"
 	"github.com/urfave/cli"
 )
 
@@ -95,8 +96,9 @@ var GlobalFlags = []cli.Flag{
 	},
 	cli.IntFlag{
 		Name:   "workers, w",
-		Usage:  "`LIMIT` the number of indexing workers to reduce system load",
+		Usage:  "adjusts `MAX` number of indexing workers",
 		EnvVar: "PHOTOPRISM_WORKERS",
+		Value:  cpuid.CPU.PhysicalCores / 2,
 	},
 	cli.IntFlag{
 		Name:   "wakeup-interval",