BenchmarkRPC/client_to_client_via_server fails

[ggyuchive]

What happened:

• During bench test, BenchmarkRPC/client_to_client_via_server-4 fails sporadically with below message.

BenchmarkRPC/client_to_client_via_server-4                              	fatal error: concurrent map iteration and map write

• Goroutine stack trace can be found in below link. Test runs with some changes, but not relevant to this test.
  https://github.com/yorkie-team/yorkie/actions/runs/17016008924/job/48238460355

What you expected to happen:

• It's because watchDoc reads llrb node and benchmarkUpdateAndSync try to change same llrb node, those execute simultaneously.

go func() {
	defer wg.Done()
	watchDoc(ctx, b, c1, d1, rch1, done2)
}()

go func() {
	benchmarkUpdateAndSync(b, ctx, 50, c1, d1, testKey1)
	done1 <- true
}()

• If this concurrent behavior is possible in Yorkie, lock can be needed. If not, should modify testscript.

How to reproduce it (as minimally and precisely as possible):
go test -tags bench -race -bench=BenchmarkRPC/client_to_client_via_server ./test/bench
OR
go test -tags bench -bench=BenchmarkRPC/client_to_client_via_server -count=100 ./test/bench to catch sporadic failure.

==================
WARNING: DATA RACE
Write at 0x00c000ea2bc8 by goroutine 214:
  github.com/yorkie-team/yorkie/pkg/llrb.rotateLeft[go.shape.*uint8,go.shape.*uint8]()
      /Users/I588818/yorkieProject/yorkie/pkg/llrb/llrb.go:213 +0x3a0
  github.com/yorkie-team/yorkie/pkg/llrb.(*Tree[go.shape.*uint8,go.shape.*uint8]).put()
      /Users/I588818/yorkieProject/yorkie/pkg/llrb/llrb.go:160 +0x288
  github.com/yorkie-team/yorkie/pkg/llrb.(*Tree[go.shape.*uint8,go.shape.*uint8]).put()
      /Users/I588818/yorkieProject/yorkie/pkg/llrb/llrb.go:154 +0xdc
  github.com/yorkie-team/yorkie/pkg/llrb.(*Tree[go.shape.*uint8,go.shape.*uint8]).put()
      /Users/I588818/yorkieProject/yorkie/pkg/llrb/llrb.go:154 +0xdc
  github.com/yorkie-team/yorkie/pkg/llrb.(*Tree[go.shape.*uint8,go.shape.*uint8]).Put()
      /Users/I588818/yorkieProject/yorkie/pkg/llrb/llrb.go:76 +0x1f8
  github.com/yorkie-team/yorkie/pkg/document/crdt.(*RGATreeSplit[go.shape.*uint8]).InsertAfter()
      /Users/I588818/yorkieProject/yorkie/pkg/document/crdt/rga_tree_split.go:443 +0x174
  github.com/yorkie-team/yorkie/pkg/document/crdt.(*RGATreeSplit[go.shape.*uint8]).edit()
      /Users/I588818/yorkieProject/yorkie/pkg/document/crdt/rga_tree_split.go:518 +0x5fc
  github.com/yorkie-team/yorkie/pkg/document/crdt.(*Text).Edit()
      /Users/I588818/yorkieProject/yorkie/pkg/document/crdt/text.go:335 +0x23c
  github.com/yorkie-team/yorkie/pkg/document/operations.(*Edit).Execute()
      /Users/I588818/yorkieProject/yorkie/pkg/document/operations/edit.go:72 +0x168
  github.com/yorkie-team/yorkie/pkg/document/change.(*Change).Execute()
      /Users/I588818/yorkieProject/yorkie/pkg/document/change/change.go:56 +0xe0
  github.com/yorkie-team/yorkie/pkg/document.(*InternalDocument).ApplyChanges()
      /Users/I588818/yorkieProject/yorkie/pkg/document/internal_document.go:334 +0x19c
  github.com/yorkie-team/yorkie/pkg/document.(*Document).applyChanges()
      /Users/I588818/yorkieProject/yorkie/pkg/document/document.go:282 +0x118
  github.com/yorkie-team/yorkie/pkg/document.(*Document).ApplyChangePack()
      /Users/I588818/yorkieProject/yorkie/pkg/document/document.go:235 +0x164
  github.com/yorkie-team/yorkie/client.(*Client).pushPullChanges()
      /Users/I588818/yorkieProject/yorkie/client/client.go:729 +0x708
  github.com/yorkie-team/yorkie/client.(*Client).Sync()
      /Users/I588818/yorkieProject/yorkie/client/client.go:449 +0x10c
  github.com/yorkie-team/yorkie/test/bench.benchmarkUpdateAndSync()
      /Users/I588818/yorkieProject/yorkie/test/bench/grpc_bench_test.go:57 +0xd4
  github.com/yorkie-team/yorkie/test/bench.BenchmarkRPC.func3.6()
      /Users/I588818/yorkieProject/yorkie/test/bench/grpc_bench_test.go:199 +0x84

Previous read at 0x00c000ea2bc8 by goroutine 212:
  github.com/yorkie-team/yorkie/pkg/llrb.isRed[go.shape.*uint8,go.shape.*uint8]()
      /Users/I588818/yorkieProject/yorkie/pkg/llrb/llrb.go:290 +0x228
  github.com/yorkie-team/yorkie/pkg/llrb.(*Tree[go.shape.*uint8,go.shape.*uint8]).put()
      /Users/I588818/yorkieProject/yorkie/pkg/llrb/llrb.go:159 +0x1ec
  github.com/yorkie-team/yorkie/pkg/llrb.(*Tree[go.shape.*uint8,go.shape.*uint8]).put()
      /Users/I588818/yorkieProject/yorkie/pkg/llrb/llrb.go:154 +0xdc
  github.com/yorkie-team/yorkie/pkg/llrb.(*Tree[go.shape.*uint8,go.shape.*uint8]).Put()
      /Users/I588818/yorkieProject/yorkie/pkg/llrb/llrb.go:76 +0x1f8
  github.com/yorkie-team/yorkie/pkg/document/crdt.(*RGATreeSplit[go.shape.*uint8]).InsertAfter()
      /Users/I588818/yorkieProject/yorkie/pkg/document/crdt/rga_tree_split.go:443 +0x174
  github.com/yorkie-team/yorkie/pkg/document/crdt.(*RGATreeSplit[go.shape.*uint8]).edit()
      /Users/I588818/yorkieProject/yorkie/pkg/document/crdt/rga_tree_split.go:518 +0x5fc
  github.com/yorkie-team/yorkie/pkg/document/crdt.(*Text).Edit()
      /Users/I588818/yorkieProject/yorkie/pkg/document/crdt/text.go:335 +0x23c
  github.com/yorkie-team/yorkie/pkg/document/operations.(*Edit).Execute()
      /Users/I588818/yorkieProject/yorkie/pkg/document/operations/edit.go:72 +0x168
  github.com/yorkie-team/yorkie/pkg/document/change.(*Change).Execute()
      /Users/I588818/yorkieProject/yorkie/pkg/document/change/change.go:56 +0xe0
  github.com/yorkie-team/yorkie/pkg/document.(*InternalDocument).ApplyChanges()
      /Users/I588818/yorkieProject/yorkie/pkg/document/internal_document.go:334 +0x19c
  github.com/yorkie-team/yorkie/pkg/document.(*Document).applyChanges()
      /Users/I588818/yorkieProject/yorkie/pkg/document/document.go:282 +0x118
  github.com/yorkie-team/yorkie/pkg/document.(*Document).ApplyChangePack()
      /Users/I588818/yorkieProject/yorkie/pkg/document/document.go:235 +0x164
  github.com/yorkie-team/yorkie/client.(*Client).pushPullChanges()
      /Users/I588818/yorkieProject/yorkie/client/client.go:729 +0x708
  github.com/yorkie-team/yorkie/client.(*Client).Sync()
      /Users/I588818/yorkieProject/yorkie/client/client.go:449 +0x10c
  github.com/yorkie-team/yorkie/test/bench.watchDoc()
      /Users/I588818/yorkieProject/yorkie/test/bench/grpc_bench_test.go:108 +0x220
  github.com/yorkie-team/yorkie/test/bench.BenchmarkRPC.func3.4()
      /Users/I588818/yorkieProject/yorkie/test/bench/grpc_bench_test.go:191 +0xc0

Goroutine 214 (running) created at:
  github.com/yorkie-team/yorkie/test/bench.BenchmarkRPC.func3()
      /Users/I588818/yorkieProject/yorkie/test/bench/grpc_bench_test.go:198 +0x43c
  testing.(*B).runN()
      /opt/homebrew/Cellar/go/1.24.3/libexec/src/testing/benchmark.go:219 +0x1f4
  testing.(*B).run1.func1()
      /opt/homebrew/Cellar/go/1.24.3/libexec/src/testing/benchmark.go:245 +0x70

Goroutine 212 (running) created at:
  github.com/yorkie-team/yorkie/test/bench.BenchmarkRPC.func3()
      /Users/I588818/yorkieProject/yorkie/test/bench/grpc_bench_test.go:189 +0x820
  testing.(*B).runN()
      /opt/homebrew/Cellar/go/1.24.3/libexec/src/testing/benchmark.go:219 +0x1f4
  testing.(*B).run1.func1()
      /opt/homebrew/Cellar/go/1.24.3/libexec/src/testing/benchmark.go:245 +0x70
==================
--- FAIL: BenchmarkRPC/client_to_client_via_server
    testing.go:1490: race detected during execution of test
--- FAIL: BenchmarkRPC

Anything else we need to know?:

Environment:

• Operating system:
• Browser and version:
• Yorkie version (use yorkie version): v0.6.25
• Yorkie JS SDK version: