From d12fc748309763d061cadda2f9eeb91ae4b7bfc9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B8rn=20Erik=20Pedersen?=
 <bjorn.erik.pedersen@gmail.com>
Date: Mon, 29 May 2023 12:58:22 +0200
Subject: [PATCH] Fix potential deadlock in ByParam

Fixes #11039
---
 langs/language.go            | 30 ++++++++++++++++++++++--------
 resources/page/pages_sort.go |  8 +++++---
 resources/page/taxonomy.go   |  2 +-
 tpl/collections/sort.go      |  2 +-
 4 files changed, 29 insertions(+), 13 deletions(-)

diff --git a/langs/language.go b/langs/language.go
index 4e089606c7b..f8d4f64b5a6 100644
--- a/langs/language.go
+++ b/langs/language.go
@@ -41,8 +41,11 @@ type Language struct {
 	translator    locales.Translator
 	timeFormatter htime.TimeFormatter
 	tag           language.Tag
-	collator      *Collator
-	location      *time.Location
+	// collator1 and collator2 are the same, we have 2 to prevent deadlocks.
+	collator1 *Collator
+	collator2 *Collator
+
+	location *time.Location
 
 	// This is just an alias of Site.Params.
 	params maps.Params
@@ -58,14 +61,20 @@ func NewLanguage(lang, defaultContentLanguage, timeZone string, languageConfig L
 		}
 	}
 
-	var coll *Collator
+	var coll1, coll2 *Collator
 	tag, err := language.Parse(lang)
 	if err == nil {
-		coll = &Collator{
+		coll1 = &Collator{
+			c: collate.New(tag),
+		}
+		coll2 = &Collator{
 			c: collate.New(tag),
 		}
 	} else {
-		coll = &Collator{
+		coll1 = &Collator{
+			c: collate.New(language.English),
+		}
+		coll2 = &Collator{
 			c: collate.New(language.English),
 		}
 	}
@@ -76,7 +85,8 @@ func NewLanguage(lang, defaultContentLanguage, timeZone string, languageConfig L
 		translator:     translator,
 		timeFormatter:  htime.NewTimeFormatter(translator),
 		tag:            tag,
-		collator:       coll,
+		collator1:      coll1,
+		collator2:      coll2,
 	}
 
 	return l, l.loadLocation(timeZone)
@@ -165,8 +175,12 @@ func GetLocation(l *Language) *time.Location {
 	return l.location
 }
 
-func GetCollator(l *Language) *Collator {
-	return l.collator
+func GetCollator1(l *Language) *Collator {
+	return l.collator1
+}
+
+func GetCollator2(l *Language) *Collator {
+	return l.collator2
 }
 
 type Collator struct {
diff --git a/resources/page/pages_sort.go b/resources/page/pages_sort.go
index b9b905cc227..32b1b3895c2 100644
--- a/resources/page/pages_sort.go
+++ b/resources/page/pages_sort.go
@@ -161,7 +161,7 @@ var collatorStringSort = func(getString func(Page) string) func(p Pages) {
 		// Pages may be a mix of multiple languages, so we need to use the language
 		// for the currently rendered Site.
 		currentSite := p[0].Site().Current()
-		coll := langs.GetCollator(currentSite.Language())
+		coll := langs.GetCollator1(currentSite.Language())
 		coll.Lock()
 		defer coll.Unlock()
 
@@ -173,7 +173,7 @@ var collatorStringSort = func(getString func(Page) string) func(p Pages) {
 
 var collatorStringCompare = func(getString func(Page) string, p1, p2 Page) int {
 	currentSite := p1.Site().Current()
-	coll := langs.GetCollator(currentSite.Language())
+	coll := langs.GetCollator1(currentSite.Language())
 	coll.Lock()
 	c := coll.CompareStrings(getString(p1), getString(p2))
 	coll.Unlock()
@@ -182,7 +182,9 @@ var collatorStringCompare = func(getString func(Page) string, p1, p2 Page) int {
 
 var collatorStringLess = func(p Page) (less func(s1, s2 string) bool, close func()) {
 	currentSite := p.Site().Current()
-	coll := langs.GetCollator(currentSite.Language())
+	// Make sure to use the second collator to prevent deadlocks.
+	// See issue 11039.
+	coll := langs.GetCollator2(currentSite.Language())
 	coll.Lock()
 	return func(s1, s2 string) bool {
 			return coll.CompareStrings(s1, s2) < 1
diff --git a/resources/page/taxonomy.go b/resources/page/taxonomy.go
index f50152f901a..3aa0c7a7b76 100644
--- a/resources/page/taxonomy.go
+++ b/resources/page/taxonomy.go
@@ -83,7 +83,7 @@ func (i Taxonomy) Alphabetical() OrderedTaxonomy {
 		return ia
 	}
 	currentSite := p.Site().Current()
-	coll := langs.GetCollator(currentSite.Language())
+	coll := langs.GetCollator1(currentSite.Language())
 	coll.Lock()
 	defer coll.Unlock()
 	name := func(i1, i2 *OrderedTaxonomyEntry) bool {
diff --git a/tpl/collections/sort.go b/tpl/collections/sort.go
index 83029b31026..4a2106039ad 100644
--- a/tpl/collections/sort.go
+++ b/tpl/collections/sort.go
@@ -46,7 +46,7 @@ func (ns *Namespace) Sort(l any, args ...any) (any, error) {
 		return nil, errors.New("can't sort " + reflect.ValueOf(l).Type().String())
 	}
 
-	collator := langs.GetCollator(ns.deps.Conf.Language())
+	collator := langs.GetCollator1(ns.deps.Conf.Language())
 
 	// Create a list of pairs that will be used to do the sort
 	p := pairList{Collator: collator, sortComp: ns.sortComp, SortAsc: true, SliceType: sliceType}