diff --git a/imperative/python/megengine/__init__.py b/imperative/python/megengine/__init__.py
index 38291bfdea5dd9f975c294944e90bbad1f6665e5..e248be57073a8c226d4dd55e458483f9a116edb8 100644
--- a/imperative/python/megengine/__init__.py
+++ b/imperative/python/megengine/__init__.py
@@ -84,7 +84,7 @@ from .logger import enable_debug_log, get_logger, set_log_file, set_log_level
 from .serialization import load, save
 from .tensor import Parameter, Tensor, tensor
 from .utils import comp_graph_tools as cgtools
-from .utils import persistent_cache
+from .utils.persistent_cache import PersistentCacheOnServer as _PersistentCacheOnServer
 from .version import __version__
 
 _set_fork_exec_path_for_timed_func(
@@ -92,15 +92,13 @@ _set_fork_exec_path_for_timed_func(
     os.path.join(os.path.dirname(__file__), "utils", "_timed_func_fork_exec_entry.py"),
 )
 
-atexit.register(_close)
-
 del _set_fork_exec_path_for_timed_func
 
 _exit_handlers = []
 
 
 def _run_exit_handlers():
-    for handler in _exit_handlers:
+    for handler in reversed(_exit_handlers):
         handler()
     _exit_handlers.clear()
 
@@ -117,6 +115,13 @@ def _atexit(handler):
     _exit_handlers.append(handler)
 
 
+_atexit(_close)
+
+_persistent_cache = _PersistentCacheOnServer()
+_persistent_cache.reg()
+
+_atexit(_persistent_cache.flush)
+
 # subpackages
 import megengine.amp
 import megengine.autodiff
@@ -132,5 +137,3 @@ import megengine.quantization
 import megengine.random
 import megengine.utils
 import megengine.traced_module
-
-persistent_cache.get_manager()
diff --git a/imperative/python/megengine/utils/persistent_cache.py b/imperative/python/megengine/utils/persistent_cache.py
index 3b0f7ae2c07423e98ecc7141334286ea1041dda9..d517b9226ddcbaf4ff2f94146fc31c233f813639 100644
--- a/imperative/python/megengine/utils/persistent_cache.py
+++ b/imperative/python/megengine/utils/persistent_cache.py
@@ -8,87 +8,114 @@
 # "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 
 import argparse
+import contextlib
 import getpass
 import os
 import sys
 import urllib.parse
 
-from ..core._imperative_rt import PersistentCacheManager as _PersistentCacheManager
+import filelock
+
+from ..core._imperative_rt import PersistentCache as _PersistentCache
 from ..logger import get_logger
 from ..version import __version__, git_version
 
 
-class PersistentCacheManager(_PersistentCacheManager):
+class PersistentCacheOnServer(_PersistentCache):
     def __init__(self):
         super().__init__()
-        if os.getenv("MGE_FASTRUN_CACHE_TYPE") == "MEMORY":
-            get_logger().info("fastrun use in-memory cache")
-            self.open_memory()
-        elif os.getenv("MGE_FASTRUN_CACHE_TYPE") == "FILE":
-            self.open_file()
-        else:
-            self.open_redis()
-
-    def open_memory(self):
-        pass
+        cache_type = os.getenv("MGE_FASTRUN_CACHE_TYPE")
+        if cache_type not in ("FILE", "MEMORY"):
+            try:
+                redis_config = self.get_redis_config()
+            except Exception as exc:
+                get_logger().error(
+                    "failed to connect to cache server {!r}; try fallback to "
+                    "in-file cache".format(exc)
+                )
+            else:
+                self.add_config(
+                    "redis",
+                    redis_config,
+                    "fastrun use redis cache",
+                    "failed to connect to cache server",
+                )
+        if cache_type != "MEMORY":
+            path = self.get_cache_file(self.get_cache_dir())
+            self.add_config(
+                "in-file",
+                {"path": path},
+                "fastrun use in-file cache in {}".format(path),
+                "failed to create cache file in {}".format(path),
+            )
+        self.add_config(
+            "in-memory",
+            {},
+            "fastrun use in-memory cache",
+            "failed to create in-memory cache",
+        )
 
-    def open_file(self):
+    def get_cache_dir(self):
         cache_dir = os.getenv("MGE_FASTRUN_CACHE_DIR")
-        try:
-            if not cache_dir:
-                from ..hub.hub import _get_megengine_home
+        if not cache_dir:
+            from ..hub.hub import _get_megengine_home
 
-                cache_dir = os.path.expanduser(
-                    os.path.join(_get_megengine_home(), "persistent_cache.bin")
-                )
-            os.makedirs(cache_dir, exist_ok=True)
-            cache_file = os.path.join(cache_dir, "cache")
-            with open(cache_file, "a"):
-                pass
-            assert self.try_open_file(cache_file), "cannot create file"
-            get_logger().info("fastrun use in-file cache in {}".format(cache_dir))
-        except Exception as exc:
-            get_logger().error(
-                "failed to create cache file in {} {!r}; fallback to "
-                "in-memory cache".format(cache_dir, exc)
+            cache_dir = os.path.expanduser(
+                os.path.join(_get_megengine_home(), "persistent_cache")
             )
-            self.open_memory()
-
-    def open_redis(self):
+        os.makedirs(cache_dir, exist_ok=True)
+        return cache_dir
+
+    def get_cache_file(self, cache_dir):
+        cache_file = os.path.join(cache_dir, "cache.bin")
+        with open(cache_file, "a"):
+            pass
+        return cache_file
+
+    @contextlib.contextmanager
+    def lock_cache_file(self, cache_dir):
+        lock_file = os.path.join(cache_dir, "cache.lock")
+        with filelock.FileLock(lock_file):
+            yield
+
+    def get_redis_config(self):
+        url = os.getenv("MGE_FASTRUN_CACHE_URL")
+        if url is None:
+            return None
+        assert sys.platform != "win32", "redis cache on windows not tested"
         prefix = "mgbcache:{}:MGB{}:GIT:{}".format(
             getpass.getuser(), __version__, git_version
         )
-        url = os.getenv("MGE_FASTRUN_CACHE_URL")
-        if url is None:
-            self.open_file()
-        try:
-            assert sys.platform != "win32", "redis cache on windows not tested"
-            parse_result = urllib.parse.urlparse(url, scheme="redis")
-            assert parse_result.scheme == "redis", "unsupported scheme"
-            assert not parse_result.username, "redis conn with username unsupported"
-            assert self.try_open_redis(
-                parse_result.hostname, parse_result.port, parse_result.password, prefix
-            ), "connect failed"
-        except Exception as exc:
-            get_logger().error(
-                "failed to connect to cache server {!r}; try fallback to "
-                "in-file cache".format(exc)
-            )
-            self.open_file()
-
-
-_manager = None
-
+        parse_result = urllib.parse.urlparse(url)
+        assert not parse_result.username, "redis conn with username unsupported"
+        if parse_result.scheme == "redis":
+            assert parse_result.hostname and parse_result.port, "invalid url"
+            assert not parse_result.path
+            config = {
+                "hostname": parse_result.hostname,
+                "port": str(parse_result.port),
+            }
+        elif parse_result.scheme == "redis+socket":
+            assert not (parse_result.hostname or parse_result.port)
+            assert parse_result.path
+            config = {
+                "unixsocket": parse_result.path,
+            }
+        else:
+            assert False, "unsupported scheme"
+        if parse_result.password is not None:
+            config["password"] = parse_result.password
+        config["prefix"] = prefix
+        return config
 
-def get_manager():
-    global _manager
-    if _manager is None:
-        _manager = PersistentCacheManager()
-    return _manager
+    def flush(self):
+        if self.config is not None and self.config.type == "in-file":
+            with self.lock_cache_file(self.get_cache_dir()):
+                super().flush()
 
 
 def _clean():
-    nr_del = get_manager().clean()
+    nr_del = PersistentCacheOnServer().clean()
     if nr_del is not None:
         print("{} cache entries deleted".format(nr_del))
 
diff --git a/imperative/python/requires.txt b/imperative/python/requires.txt
index 58a806c05713288a481e8482760c4916b4ad8cca..894b332a02b9c87ac9c57085db6712120fc18f6b 100644
--- a/imperative/python/requires.txt
+++ b/imperative/python/requires.txt
@@ -4,8 +4,8 @@ pyarrow
 requests
 tabulate
 tqdm
-redispy
 deprecated
 mprop
 wheel
-megfile>=0.0.10
\ No newline at end of file
+megfile>=0.0.10
+filelock
diff --git a/imperative/python/src/utils.cpp b/imperative/python/src/utils.cpp
index 5162f488f31044c4c4fc5b435d63ee70b39b7c13..260c7aa268b14b98fbe4b5c9340b46d47e976137 100644
--- a/imperative/python/src/utils.cpp
+++ b/imperative/python/src/utils.cpp
@@ -210,7 +210,7 @@ void init_utils(py::module m) {
             .def("disable", [](TensorSanityCheck& checker) { checker.disable(); });
 
 #if MGB_ENABLE_OPR_MM
-    m.def("create_mm_server", &create_zmqrpc_server, py::arg("addr"),
+    m.def("create_mm_server", &mgb::opr::create_zmqrpc_server, py::arg("addr"),
           py::arg("port") = 0);
 #else
     m.def("create_mm_server", []() {});
@@ -234,51 +234,108 @@ void init_utils(py::module m) {
     using ExtendedPersistentCache =
             mgb::imperative::persistent_cache::ExtendedPersistentCache;
 
-    struct PersistentCacheManager {
-        std::shared_ptr<ExtendedPersistentCache> instance;
+    struct ConfigurablePersistentCache : mgb::PersistentCache {
+        struct Config {
+            std::string type;
+            std::unordered_map<std::string, std::string> args;
+            std::string on_success;
+            std::string on_fail;
+        };
 
-        bool try_reg(std::shared_ptr<ExtendedPersistentCache> cache) {
-            if (cache) {
-                instance = cache;
-                PersistentCache::set_impl(cache);
-                return true;
-            }
-            return false;
-        }
-        bool open_redis(
-                std::string ip, size_t port, std::string password, std::string prefix) {
-            return try_reg(mgb::imperative::persistent_cache::make_redis(
-                    ip, port, password, prefix));
+        std::shared_ptr<ExtendedPersistentCache> impl;
+        std::optional<Config> impl_config;
+        std::vector<Config> configs;
+
+        void add_config(
+                std::string type, std::unordered_map<std::string, std::string> args,
+                std::string on_success, std::string on_fail) {
+            configs.push_back({type, args, on_success, on_fail});
         }
-        bool open_file(std::string path) {
-            return try_reg(mgb::imperative::persistent_cache::make_in_file(path));
+
+        std::optional<size_t> clean() { return get_impl()->clear(); }
+
+        void load_config() {
+            std::optional<std::string> err_msg;
+            for (size_t i = 0; i < configs.size(); ++i) {
+                auto& config = configs[i];
+                if (err_msg) {
+                    mgb_log_warn("try fallback to %s cache", config.type.c_str());
+                } else {
+                    err_msg.emplace();
+                }
+                auto cache = ExtendedPersistentCache::make_from_config(
+                        config.type, config.args, *err_msg);
+                if (!cache) {
+                    mgb_log_warn("%s %s", config.on_fail.c_str(), err_msg->c_str());
+                } else {
+                    impl = cache;
+                    impl_config = config;
+                    break;
+                }
+            }
+            mgb_assert(impl_config.has_value(), "not valid config");
         }
-        std::optional<size_t> clean() {
-            if (instance) {
-                return instance->clear();
+
+        std::shared_ptr<ExtendedPersistentCache> get_impl() {
+            if (!impl) {
+                load_config();
             }
-            return {};
+            return impl;
         }
-        void put(std::string category, std::string key, std::string value) {
-            PersistentCache::inst().put(
-                    category, {key.data(), key.size()}, {value.data(), value.size()});
+
+        virtual mgb::Maybe<Blob> get(const std::string& category, const Blob& key) {
+            return get_impl()->get(category, key);
+        }
+
+        virtual void put(
+                const std::string& category, const Blob& key, const Blob& value) {
+            return get_impl()->put(category, key, value);
         }
-        py::object get(std::string category, std::string key) {
-            auto value =
-                    PersistentCache::inst().get(category, {key.data(), key.size()});
+
+        virtual bool support_dump_cache() { return get_impl()->support_dump_cache(); }
+
+        py::object py_get(std::string category, std::string key) {
+            auto value = get_impl()->get(category, {key.data(), key.size()});
             if (value.valid()) {
                 return py::bytes(std::string((const char*)value->ptr, value->size));
             } else {
                 return py::none();
             }
         }
+
+        void py_put(std::string category, std::string key, std::string value) {
+            get_impl()->put(
+                    category, {key.data(), key.size()}, {value.data(), value.size()});
+        }
+
+        void flush() {
+            if (impl) {
+                impl->flush();
+            }
+        }
     };
 
-    py::class_<PersistentCacheManager>(m, "PersistentCacheManager")
-            .def(py::init<>())
-            .def("try_open_redis", &PersistentCacheManager::open_redis)
-            .def("try_open_file", &PersistentCacheManager::open_file)
-            .def("clean", &PersistentCacheManager::clean)
-            .def("put", &PersistentCacheManager::put)
-            .def("get", &PersistentCacheManager::get);
+    auto PyConfigurablePersistentCache =
+            py::class_<
+                    ConfigurablePersistentCache,
+                    std::shared_ptr<ConfigurablePersistentCache>>(m, "PersistentCache")
+                    .def(py::init<>())
+                    .def("add_config", &ConfigurablePersistentCache::add_config)
+                    .def("reg",
+                         [](std::shared_ptr<ConfigurablePersistentCache> inst) {
+                             PersistentCache::set_impl(inst);
+                         })
+                    .def("clean", &ConfigurablePersistentCache::clean)
+                    .def("get", &ConfigurablePersistentCache::py_get)
+                    .def("put", &ConfigurablePersistentCache::py_put)
+                    .def_readonly("config", &ConfigurablePersistentCache::impl_config)
+                    .def("flush", &ConfigurablePersistentCache::flush);
+
+    py::class_<ConfigurablePersistentCache::Config>(
+            PyConfigurablePersistentCache, "Config")
+            .def_readwrite("type", &ConfigurablePersistentCache::Config::type)
+            .def_readwrite("args", &ConfigurablePersistentCache::Config::args)
+            .def_readwrite("on_fail", &ConfigurablePersistentCache::Config::on_fail)
+            .def_readwrite(
+                    "on_success", &ConfigurablePersistentCache::Config::on_success);
 }
diff --git a/imperative/src/impl/ops/collective_comm.cpp b/imperative/src/impl/ops/collective_comm.cpp
index 6c969a2283b01695cd255b74a04aea9fee4e2e3f..141f7f625d9b09a23d5294c31a2cf60c407e4b2f 100644
--- a/imperative/src/impl/ops/collective_comm.cpp
+++ b/imperative/src/impl/ops/collective_comm.cpp
@@ -27,7 +27,7 @@ namespace imperative {
 namespace {
 cg::OperatorNodeBase* apply_on_var_node(const OpDef& def, const VarNodeArray& inputs) {
     auto&& comm = def.cast_final_safe<CollectiveComm>();
-    auto group_client = std::make_shared<GroupClientProxy>(
+    auto group_client = std::make_shared<opr::GroupClientProxy>(
             ssprintf("%s:%d", comm.addr.data(), comm.port));
     SmallVector<std::shared_ptr<mgb::DeviceTensorND>> dev_buffer_arr(1, nullptr);
     auto disable = std::make_shared<DTypeScalar>();
diff --git a/imperative/src/impl/ops/io_remote.cpp b/imperative/src/impl/ops/io_remote.cpp
index 29b0316ee657d506e2b4daac5aa3591935e48658..03e4d58ab3a0fa6d1776a38660586a075567b794 100644
--- a/imperative/src/impl/ops/io_remote.cpp
+++ b/imperative/src/impl/ops/io_remote.cpp
@@ -28,7 +28,7 @@ namespace {
 cg::OperatorNodeBase* apply_on_var_node_remote_send(
         const OpDef& def, const VarNodeArray& inputs) {
     auto&& send = def.cast_final_safe<RemoteSend>();
-    auto group_client = std::make_shared<GroupClientProxy>(
+    auto group_client = std::make_shared<opr::GroupClientProxy>(
             ssprintf("%s:%d", send.addr.data(), send.port));
     auto&& graph = inputs[0]->owner_graph();
 
@@ -44,7 +44,7 @@ cg::OperatorNodeBase* apply_on_var_node_remote_recv(
     auto&& recv = def.cast_final_safe<RemoteRecv>();
     OperatorNodeConfig config{recv.cn};
     config.name(recv.make_name());
-    auto group_client = std::make_shared<GroupClientProxy>(
+    auto group_client = std::make_shared<opr::GroupClientProxy>(
             ssprintf("%s:%d", recv.addr.data(), recv.port));
     auto&& graph = inputs[0]->owner_graph();
     return graph->insert_opr(std::make_unique<mgb::opr::RemoteRecv>(
diff --git a/imperative/src/impl/persistent_cache.cpp b/imperative/src/impl/persistent_cache.cpp
index ba3809abb04cb6962e2291ccdd04da398dbf49a3..5fc291c8a6d8c8a9a56e4a483fb8fa543fec6c9d 100644
--- a/imperative/src/impl/persistent_cache.cpp
+++ b/imperative/src/impl/persistent_cache.cpp
@@ -27,8 +27,10 @@ public:
         m_local = std::make_shared<mgb::InMemoryPersistentCache>();
     }
 
-    bool connect(std::string ip, size_t port, std::string password) {
-        m_client.auth(password);
+    void connect(std::string ip, size_t port, std::optional<std::string> password) {
+        if (password) {
+            m_client.auth(*password);
+        }
         m_client.connect(
                 ip, port,
                 [](const std::string& host, std::size_t port,
@@ -40,16 +42,32 @@ public:
                     }
                 },
                 std::uint32_t(200));
-        if (!m_client.is_connected()) {
-            return false;
-        }
+        mgb_assert(m_client.is_connected(), "connect failed");
         auto flag = m_client.get("mgb-cache-flag");
         sync();
-        return flag.get().ok();
+        auto is_valid = [](const cpp_redis::reply& reply) {
+            switch (reply.get_type()) {
+                case cpp_redis::reply::type::error:
+                case cpp_redis::reply::type::null:
+                    return false;
+                case cpp_redis::reply::type::integer:
+                    return reply.as_integer() != 0;
+                case cpp_redis::reply::type::simple_string:
+                case cpp_redis::reply::type::bulk_string:
+                    return !reply.as_string().empty();
+                case cpp_redis::reply::type::array:
+                    return !reply.as_array().empty();
+                default:
+                    mgb_assert(false, "unknown reply type %d", (int)reply.get_type());
+            }
+        };
+        mgb_assert(is_valid(flag.get()), "invalid mgb-cache-flag");
     }
 
     bool valid() const override { return m_client.is_connected(); }
 
+    void flush() override {}
+
     mgb::Maybe<Blob> get(const std::string& category, const Blob& key) override {
         MGB_LOCK_GUARD(m_mtx);
         auto mem_result = m_local->get(category, key);
@@ -75,7 +93,7 @@ public:
         MGB_LOCK_GUARD(m_mtx);
         std::string key_str(static_cast<const char*>(key.ptr), key.size);
         std::string redis_key_str;
-        encode(category + '@' + key_str, redis_key_str);
+        encode(category + '@' + key_str, redis_key_str, 24);
         std::string value_str(static_cast<const char*>(value.ptr), value.size);
         std::string redis_value_str;
         encode(value_str, redis_value_str);
@@ -118,18 +136,16 @@ private:
 
 class ExtendedInFilePersistentCache final : public ExtendedPersistentCache {
 private:
-    std::string m_path;
+    std::optional<std::string> m_path;
     std::unique_ptr<mgb::InFilePersistentCache> m_impl;
 
 public:
     ExtendedInFilePersistentCache() = default;
 
-    bool open(std::string path) {
+    void open(std::string path) {
         std::fstream file;
         file.open(path, std::ios::in | std::ios::binary);
-        if (!file.is_open()) {
-            return false;
-        }
+        mgb_assert(file.is_open(), "can't open file in %s", path.c_str());
         std::vector<char> bytes = {
                 std::istreambuf_iterator<char>(file), std::istreambuf_iterator<char>()};
         if (bytes.size()) {
@@ -139,14 +155,11 @@ public:
             m_impl = std::make_unique<mgb::InFilePersistentCache>();
         }
         m_path = path;
-        return true;
     }
 
-    ~ExtendedInFilePersistentCache() {
-        if (m_impl) {
-            m_impl->dump_cache(m_path.c_str());
-        }
-    }
+    void open() { m_impl = std::make_unique<mgb::InFilePersistentCache>(); }
+
+    ~ExtendedInFilePersistentCache() { flush(); }
 
     mgb::Maybe<Blob> get(const std::string& category, const Blob& key) override {
         return m_impl->get(category, key);
@@ -157,29 +170,64 @@ public:
     }
 
     std::optional<size_t> clear() override {
-        m_impl = std::make_unique<mgb::InFilePersistentCache>();
-        m_impl->dump_cache(m_path.c_str());
+        if (m_impl) {
+            m_impl = std::make_unique<mgb::InFilePersistentCache>();
+            if (m_path) {
+                m_impl->dump_cache(m_path->c_str());
+            }
+        }
         return {};
     }
 
     bool valid() const override { return m_impl != nullptr; }
-};
 
-std::shared_ptr<ExtendedPersistentCache> make_redis(
-        std::string ip, size_t port, std::string password, std::string prefix) {
-    auto cache = std::make_shared<RedisCache>(prefix, 100);
-    if (!cache->connect(ip, port, password)) {
-        return nullptr;
+    void flush() override {
+        if (m_impl && m_path) {
+            m_impl->dump_cache(m_path->c_str());
+        }
     }
-    return cache;
-}
+};
 
-std::shared_ptr<ExtendedPersistentCache> make_in_file(std::string path) {
-    auto cache = std::make_shared<ExtendedInFilePersistentCache>();
-    if (!cache->open(path)) {
-        return nullptr;
+std::shared_ptr<ExtendedPersistentCache> ExtendedPersistentCache::make_from_config(
+        std::string type, std::unordered_map<std::string, std::string> args,
+        std::string& err_msg) {
+    try {
+        if (type == "redis") {
+            std::string prefix = args.at("prefix");
+            std::optional<std::string> password = args.count("password")
+                                                        ? args.at("password")
+                                                        : std::optional<std::string>();
+            auto cache = std::make_shared<RedisCache>(prefix, 100);
+            if (args.count("unixsocket")) {
+                std::string unixsocket = args.at("unixsocket");
+                cache->connect(unixsocket, 0, password);
+            } else {
+                std::string ip = args.at("hostname");
+                int port = atoi(args.at("port").c_str());
+                std::optional<std::string> password =
+                        args.count("password") ? args.at("password")
+                                               : std::optional<std::string>();
+                cache->connect(ip, port, password);
+            }
+            return cache;
+        } else if (type == "in-file") {
+            std::string path = args.at("path");
+            auto cache = std::make_shared<ExtendedInFilePersistentCache>();
+            cache->open(path);
+            return cache;
+        } else if (type == "in-memory") {
+            auto cache = std::make_shared<ExtendedInFilePersistentCache>();
+            cache->open();
+            return cache;
+        } else {
+            mgb_assert(false, "persistent cache type %s unsupported", type.c_str());
+        }
+    } catch (const std::exception& exc) {
+        err_msg = exc.what();
+    } catch (...) {
+        err_msg = "unknown exception";
     }
-    return cache;
+    return nullptr;
 }
 
 }  // namespace mgb::imperative::persistent_cache
diff --git a/imperative/src/include/megbrain/imperative/persistent_cache.h b/imperative/src/include/megbrain/imperative/persistent_cache.h
index 59326bbdedfddcc4ca6eaf2f4ba6caf375cd3d8f..4d63eaae7a66010e17fc0c87824c9c3580304c7c 100644
--- a/imperative/src/include/megbrain/imperative/persistent_cache.h
+++ b/imperative/src/include/megbrain/imperative/persistent_cache.h
@@ -20,12 +20,12 @@ class ExtendedPersistentCache : public mgb::PersistentCache {
 public:
     virtual bool valid() const = 0;
     virtual std::optional<size_t> clear() = 0;
-};
-
-std::shared_ptr<ExtendedPersistentCache> make_redis(
-        std::string ip, size_t port, std::string password, std::string prefix);
+    virtual void flush() = 0;
 
-std::shared_ptr<ExtendedPersistentCache> make_in_file(std::string path);
+    static std::shared_ptr<ExtendedPersistentCache> make_from_config(
+            std::string type, std::unordered_map<std::string, std::string> args,
+            std::string& err_msg);
+};
 
 }  // namespace mgb::imperative::persistent_cache
 // vim: syntax=cpp.doxygen foldmethod=marker foldmarker=f{{{,f}}}
diff --git a/imperative/src/test/collective_comm.cpp b/imperative/src/test/collective_comm.cpp
index 01c0829dd78b4127e61cc3a6462d317c74bfc89c..4a31c54be31ad62883ec581c5b64d02083b3bbe1 100644
--- a/imperative/src/test/collective_comm.cpp
+++ b/imperative/src/test/collective_comm.cpp
@@ -20,7 +20,7 @@ TEST(TestImperative, AllReduceBasic) {
     REQUIRE_GPU(2);
     const char* server_addr = "127.0.0.1";
     uint32_t port = 3456;
-    mgb_assert(create_zmqrpc_server(server_addr, port) > 0);
+    mgb_assert(opr::create_zmqrpc_server(server_addr, port) > 0);
     HostTensorGenerator<> gen;
     CompNode cn0 = CompNode::load("gpu0"), cn1 = CompNode::load("gpu1");
 
diff --git a/imperative/src/test/io_remote.cpp b/imperative/src/test/io_remote.cpp
index 8e32f7abd4f1c8c9a99583e8af18bc0cc6a4f2bc..97a7b62dddfefe94b5d18acb65b5a4214c2978d0 100644
--- a/imperative/src/test/io_remote.cpp
+++ b/imperative/src/test/io_remote.cpp
@@ -20,7 +20,7 @@ TEST(TestImperative, IORemote) {
     REQUIRE_GPU(2);
     const char* server_addr = "127.0.0.1";
     uint32_t port = 4567;
-    mgb_assert(create_zmqrpc_server(server_addr, port) > 0);
+    mgb_assert(opr::create_zmqrpc_server(server_addr, port) > 0);
     HostTensorGenerator<> gen;
     CompNode cn0 = CompNode::load("gpu0"), cn1 = CompNode::load("gpu1");
 
diff --git a/src/opr-mm/impl/mm_handler.cpp b/src/opr-mm/impl/mm_handler.cpp
index 1f13b6974d7f057d97e8fb17d2c4b5ac8328217b..7cbb8a3ec54489f740d903df19d234d25bcd8f07 100644
--- a/src/opr-mm/impl/mm_handler.cpp
+++ b/src/opr-mm/impl/mm_handler.cpp
@@ -17,6 +17,9 @@
 #include "megbrain/opr/zmq_rpc.h"
 #include "mm_handler.pb.h"
 
+using namespace mgb;
+using namespace opr;
+
 /* ======================== GroupServerProxy ========================== */
 /*!
  * A proxy that receives zmqrpc call, direct call to NCCL Manager
@@ -213,7 +216,7 @@ struct ServerInfo {
     std::unique_ptr<ZmqRpc::ZmqRpcServer> server;
 };
 
-int create_zmqrpc_server(const std::string& server_addr, int port) {
+int mgb::opr::create_zmqrpc_server(const std::string& server_addr, int port) {
     static std::unordered_map<std::string, ServerInfo> addr2server;
     static std::mutex mtx;
     MGB_LOCK_GUARD(mtx);
diff --git a/src/opr-mm/include/megbrain/opr/mm_handler.h b/src/opr-mm/include/megbrain/opr/mm_handler.h
index 7c03bf961cb7efbc53679d6ff00a5290e4fdd08f..97b829d446b46cda9b47d39856212b963a2dd5cf 100644
--- a/src/opr-mm/include/megbrain/opr/mm_handler.h
+++ b/src/opr-mm/include/megbrain/opr/mm_handler.h
@@ -16,8 +16,8 @@
 #include "megbrain/opr/collective_comm.h"
 #include "megbrain/opr/group_manager.h"
 
-using namespace mgb;
-using namespace opr;
+namespace mgb {
+namespace opr {
 
 /*!
  * Comm MM Client Proxy.
@@ -56,6 +56,9 @@ private:
 
 int create_zmqrpc_server(const std::string& server_addr, int port);
 
+}  // namespace opr
+}  // namespace mgb
+
 #endif
 
 // vim: syntax=cpp.doxygen foldmethod=marker foldmarker=f{{{,f}}}
diff --git a/src/version.ld b/src/version.ld
index db71a72b3a2f8003aef62ce11a39c422dd0221a6..f70a5677511a7c2588a780b2c401f603e95bbde4 100644
--- a/src/version.ld
+++ b/src/version.ld
@@ -13,8 +13,6 @@ global:
         base_exceptions*;
     };
     megcore*;
-    *GroupClientProxy*;
-    *create_zmqrpc_server*;
     *custom*;