From e36e12fec21b16f3177417ce3c4d34f3f79aeede Mon Sep 17 00:00:00 2001
From: Matt Joiner <anacrolix@gmail.com>
Date: Tue, 5 Aug 2025 19:54:51 +1000
Subject: [PATCH] Add TORRENT_MAX_ACTIVE_PIECE_HASHERS

---
 client.go             |  4 +++-
 env.go                | 18 ++++++++++++++++++
 webseed-requesting.go |  9 +--------
 3 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/client.go b/client.go
index 4c3c6dc2..f67f2a89 100644
--- a/client.go
+++ b/client.go
@@ -1962,8 +1962,10 @@ func (cl *Client) checkConfig() error {
 	return nil
 }
 
+var maxActivePieceHashers = initIntFromEnv("TORRENT_MAX_ACTIVE_PIECE_HASHERS", runtime.NumCPU(), 0)
+
 func (cl *Client) maxActivePieceHashers() int {
-	return runtime.NumCPU()
+	return maxActivePieceHashers
 }
 
 func (cl *Client) belowMaxActivePieceHashers() bool {
diff --git a/env.go b/env.go
index 10cbafc7..c8759d6e 100644
--- a/env.go
+++ b/env.go
@@ -1 +1,19 @@
 package torrent
+
+import (
+	"os"
+	"strconv"
+
+	"github.com/anacrolix/missinggo/v2/panicif"
+	"golang.org/x/exp/constraints"
+)
+
+func initIntFromEnv[T constraints.Integer](key string, defaultValue T, bitSize int) T {
+	s := os.Getenv(key)
+	if s == "" {
+		return defaultValue
+	}
+	i64, err := strconv.ParseInt(s, 10, bitSize)
+	panicif.Err(err)
+	return T(i64)
+}
diff --git a/webseed-requesting.go b/webseed-requesting.go
index a4cc17d5..698eea79 100644
--- a/webseed-requesting.go
+++ b/webseed-requesting.go
@@ -9,7 +9,6 @@ import (
 	"maps"
 	"os"
 	"runtime/pprof"
-	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -24,13 +23,7 @@ import (
 	"github.com/anacrolix/torrent/webseed"
 )
 
-var webseedHostRequestConcurrency int
-
-func init() {
-	i64, err := strconv.ParseInt(cmp.Or(os.Getenv("TORRENT_WEBSEED_HOST_REQUEST_CONCURRENCY"), "10"), 10, 0)
-	panicif.Err(err)
-	webseedHostRequestConcurrency = int(i64)
-}
+var webseedHostRequestConcurrency = initIntFromEnv("TORRENT_WEBSEED_HOST_REQUEST_CONCURRENCY", 10, 0)
 
 type (
 	webseedHostKey       string
-- 
2.51.0