membuffer: fix data race when IsReadOnly and Set may be concurrently invoked
#4273
| Job | Run time |
|---|---|
| 4m 33s | |
| 4m 33s |
IsReadOnly and Set may be concurrently invoked
#4273
| Job | Run time |
|---|---|
| 4m 33s | |
| 4m 33s |