From 82d9d8687ba6f857bcc94002d664dfa86ce041d3 Mon Sep 17 00:00:00 2001
From: Chris Lu <chrislusf@users.noreply.github.com>
Date: Thu, 5 Feb 2026 10:24:18 -0800
Subject: [PATCH] Fix concurrent map access in EC shards info (#8222)

* fix concurrent map access in EC shards info #8219

* refactor: simplify Disk.ToDiskInfo to use ecShards snapshot and avoid redundant locking

* refactor: improve GetEcShards with pre-allocation and defer
---
 .../erasure_coding/ec_shards_info_test.go     | 44 +++++++++++++++++++
 weed/topology/disk_ec.go                      |  5 ++-
 weed/topology/race_condition_stress_test.go   | 44 +++++++++++++++++++
 3 files changed, 91 insertions(+), 2 deletions(-)

diff --git a/weed/storage/erasure_coding/ec_shards_info_test.go b/weed/storage/erasure_coding/ec_shards_info_test.go
index 523217417..f96fbbca6 100644
--- a/weed/storage/erasure_coding/ec_shards_info_test.go
+++ b/weed/storage/erasure_coding/ec_shards_info_test.go
@@ -1,6 +1,7 @@
 package erasure_coding
 
 import (
+	"sync"
 	"testing"
 
 	"github.com/seaweedfs/seaweedfs/weed/pb/master_pb"
@@ -364,3 +365,46 @@ func BenchmarkShardsInfo_Size(b *testing.B) {
 		si.Size(ShardId(i % TotalShardsCount))
 	}
 }
+
+func TestShardsInfo_ConcurrentAccess(t *testing.T) {
+	si := NewShardsInfo()
+
+	var wg sync.WaitGroup
+	wg.Add(3)
+
+	// Goroutine 1: Continuously Set/Delete shards
+	go func() {
+		defer wg.Done()
+		for i := 0; i < 1000; i++ {
+			si.Set(ShardInfo{Id: ShardId(i % TotalShardsCount), Size: 100})
+			if i%10 == 0 {
+				si.Delete(ShardId((i / 10) % TotalShardsCount))
+			}
+		}
+	}()
+
+	// Goroutine 2: Continuously read Info (Sizes, Bitmap, Count)
+	go func() {
+		defer wg.Done()
+		for i := 0; i < 1000; i++ {
+			si.Sizes()
+			si.Bitmap()
+			si.Count()
+			si.TotalSize()
+		}
+	}()
+
+	// Goroutine 3: Continuously Add/Subtract from another ShardsInfo
+	go func() {
+		defer wg.Done()
+		other := NewShardsInfo()
+		other.Set(ShardInfo{Id: 1, Size: 100})
+		other.Set(ShardInfo{Id: 2, Size: 200})
+		for i := 0; i < 1000; i++ {
+			si.Add(other)
+			si.Subtract(other)
+		}
+	}()
+
+	wg.Wait()
+}
diff --git a/weed/topology/disk_ec.go b/weed/topology/disk_ec.go
index a783b309e..6ad3ac958 100644
--- a/weed/topology/disk_ec.go
+++ b/weed/topology/disk_ec.go
@@ -7,11 +7,12 @@ import (
 )
 
 func (d *Disk) GetEcShards() (ret []*erasure_coding.EcVolumeInfo) {
-	d.RLock()
+	d.ecShardsLock.RLock()
+	defer d.ecShardsLock.RUnlock()
+	ret = make([]*erasure_coding.EcVolumeInfo, 0, len(d.ecShards))
 	for _, ecVolumeInfo := range d.ecShards {
 		ret = append(ret, ecVolumeInfo)
 	}
-	d.RUnlock()
 	return ret
 }
 
diff --git a/weed/topology/race_condition_stress_test.go b/weed/topology/race_condition_stress_test.go
index 79c460590..6d8d9260c 100644
--- a/weed/topology/race_condition_stress_test.go
+++ b/weed/topology/race_condition_stress_test.go
@@ -8,6 +8,8 @@ import (
 	"time"
 
 	"github.com/seaweedfs/seaweedfs/weed/sequence"
+	"github.com/seaweedfs/seaweedfs/weed/storage/erasure_coding"
+	"github.com/seaweedfs/seaweedfs/weed/storage/needle"
 	"github.com/seaweedfs/seaweedfs/weed/storage/super_block"
 	"github.com/seaweedfs/seaweedfs/weed/storage/types"
 )
@@ -304,3 +306,45 @@ func TestReservationSystemPerformance(t *testing.T) {
 		t.Logf("Performance test passed: %v per reservation", avgDuration)
 	}
 }
+
+func TestDisk_GetEcShards_Race(t *testing.T) {
+	d := NewDisk("hdd")
+
+	// Pre-populate with one shard
+	initialShard := &erasure_coding.EcVolumeInfo{
+		VolumeId:   needle.VolumeId(1),
+		ShardsInfo: erasure_coding.NewShardsInfo(),
+	}
+	initialShard.ShardsInfo.Set(erasure_coding.ShardInfo{Id: 0, Size: 100})
+	d.AddOrUpdateEcShard(initialShard)
+
+	var wg sync.WaitGroup
+	wg.Add(10)
+
+	// Goroutine 1-5: Continuously read shards
+	for j := 0; j < 5; j++ {
+		go func() {
+			defer wg.Done()
+			for i := 0; i < 10000; i++ {
+				d.GetEcShards()
+			}
+		}()
+	}
+
+	// Goroutine 6-10: Continuously update shards
+	for j := 0; j < 5; j++ {
+		go func() {
+			defer wg.Done()
+			for i := 0; i < 10000; i++ {
+				shard := &erasure_coding.EcVolumeInfo{
+					VolumeId:   needle.VolumeId(i % 100),
+					ShardsInfo: erasure_coding.NewShardsInfo(),
+				}
+				shard.ShardsInfo.Set(erasure_coding.ShardInfo{Id: erasure_coding.ShardId(i % 14), Size: 100})
+				d.AddOrUpdateEcShard(shard)
+			}
+		}()
+	}
+
+	wg.Wait()
+}