[feat] support prefix cache clearing when /clear_load_weight is called (#4091)

* [feat] support clearing prefix cache (cherry-picked from release/2.1)

* [fix] fix ipc suffix, use port instead

* [fix] fix prefix caching not enabled

* [fix] fix code style

* [fix] wait for rank0 to update weight status

Author: liyonghua0910

custom_ops/gpu_ops/unset_data_ipc.cu

@@ -0,0 +1,71 @@
+// Copyright (c) 2025 PaddlePaddle Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "helper.h"
+#include "cuda_multiprocess.h"
+
+#if !defined(_WIN32)
+#include <errno.h>
+#include <string.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#endif
+
+// 可选：仅删除/解除共享内存命名对象（不依赖之前保存的 addr/fd）
+static inline int sharedMemoryUnlinkByName(const char* name) {
+#if defined(WIN32) || defined(_WIN32) || defined(WIN64) || defined(_WIN64)
+  // Windows 上没有 shm_unlink 语义。命名对象在最后一个句柄关闭后消失。
+  // 这里做“尽力而为”：尝试打开后立即关闭，减少一次引用。
+  HANDLE hMap = OpenFileMappingA(FILE_MAP_ALL_ACCESS, FALSE, name);
+  if (hMap) {
+    CloseHandle(hMap);
+    return 0;
+  }
+  // 已经不存在也算成功
+  return 0;
+#else
+  // POSIX: 移除名字，未来不可再 open；已映射区仍存活直至 munmap
+  if (shm_unlink(name) != 0) {
+    if (errno == ENOENT) return 0;  // 不存在视作成功
+    return errno;
+  }
+  return 0;
+#endif
+}
+
+void UnsetDataIpc(const paddle::Tensor& tmp_input,
+                         const std::string& shm_name,
+                         bool close_ipc,
+                         bool unlink_shm) {
+  // 1) 关闭消费者导入的 IPC 映射（仅当 close_ipc=true 且该指针确为 OpenMemHandle 得来）
+  if (close_ipc) {
+    void* ptr = const_cast<void*>(tmp_input.data());
+    checkCudaErrors(cudaIpcCloseMemHandle(ptr));
+  }
+
+  // 2) 解除共享内存命名对象（仅处理“名字”，不保证解除旧映射）
+  if (unlink_shm) {
+    int rc = sharedMemoryUnlinkByName(shm_name.c_str());
+    if (rc != 0) {
+      PD_THROW("Unlink shared memory failed: name=%s, err=%d",
+               shm_name.c_str(), rc);
+    }
+  }
+}
+
+PD_BUILD_STATIC_OP(unset_data_ipc)
+    .Inputs({"tmp_input"})
+    .Attrs({"shm_name: std::string", "close_ipc: bool", "unlink_shm: bool"})
+    .SetKernelFn(PD_KERNEL(UnsetDataIpc));

custom_ops/setup_ops.py

@@ -208,6 +208,7 @@ def find_end_files(directory, end_str):
         "gpu_ops/rebuild_padding.cu",
         "gpu_ops/step.cu",
         "gpu_ops/set_data_ipc.cu",
+        "gpu_ops/unset_data_ipc.cu",
         "gpu_ops/moe/tritonmoe_preprocess.cu",
         "gpu_ops/step_system_cache.cu",
         "gpu_ops/get_output_ep.cc",
@@ -278,6 +279,7 @@ def find_end_files(directory, end_str):
         "gpu_ops/beam_search_softmax.cu",
         "gpu_ops/rebuild_padding.cu",
         "gpu_ops/set_data_ipc.cu",
+        "gpu_ops/unset_data_ipc.cu",
         "gpu_ops/read_data_ipc.cu",
         "gpu_ops/enforce_generation.cu",
         "gpu_ops/dequant_int8.cu",

fastdeploy/cache_manager/cache_messager.py

@@ -98,8 +98,8 @@ def __init__(
         cache_v = []
         self.messager = {}
         for layer_idx in range(self.num_layers):
-            key_cache = self.gpu_cache_kvs[f"key_caches_{layer_idx}_rank{self.rank}_device{gpu_id}"]
-            val_cache = self.gpu_cache_kvs[f"value_caches_{layer_idx}_rank{self.rank}_device{gpu_id}"]
+            key_cache = self.gpu_cache_kvs[f"key_caches_{layer_idx}_rank{self.rank}.device{gpu_id}"]
+            val_cache = self.gpu_cache_kvs[f"value_caches_{layer_idx}_rank{self.rank}.device{gpu_id}"]
             cache_k.append(key_cache)
             cache_v.append(val_cache)
             cache_k_ptr_list.append(key_cache.data_ptr())

fastdeploy/cache_manager/cache_transfer_manager.py

@@ -16,21 +16,27 @@
 
 import argparse
 import concurrent.futures
+import gc
 import json
 import queue
+import threading
 import time
 import traceback
 
 import numpy as np
 import paddle
 
+from fastdeploy import envs
 from fastdeploy.cache_manager.cache_data import CacheStatus
 from fastdeploy.config import SpeculativeConfig
-from fastdeploy.inter_communicator import EngineCacheQueue, IPCSignal
+from fastdeploy.inter_communicator import EngineCacheQueue, IPCSignal, KVCacheStatus
 from fastdeploy.model_executor.ops.gpu import (
     cuda_host_alloc,
+    cuda_host_free,
     set_data_ipc,
+    share_external_data,
     swap_cache_all_layers,
+    unset_data_ipc,
 )
 from fastdeploy.utils import get_logger
 
@@ -93,6 +99,7 @@ def parse_args():
         help="speculative config",
     )
     parser.add_argument("--local_data_parallel_id", type=int, default=0)
+    parser.add_argument("--create_cache_tensor", action="store_true")
 
     args = parser.parse_args()
     return args
@@ -110,7 +117,6 @@ def __init__(self, args):
 
         device = args.device_id
         rank = args.rank
-        paddle.set_device(f"gpu:{device}")
         self.gpu_cache_kvs = {}
         self.cpu_cache_kvs = {}
         self.gpu_cache_k_tensors = []
@@ -126,6 +132,7 @@ def __init__(self, args):
         self.n_ranks = args.mp_num
         self.rank = rank
         self.device = device
+        self.engine_pid = args.engine_pid
 
         address = (args.pod_ip, args.cache_queue_port)
         self.cache_task_queue = EngineCacheQueue(
@@ -136,70 +143,27 @@ def __init__(self, args):
             local_data_parallel_id=args.local_data_parallel_id,
         )
 
-        self.num_cpu_blocks = args.num_cpu_blocks
-
-        cache_type = args.cache_dtype
-        for i in range(args.num_layers + self.num_extra_layers):
-            num_gpu_blocks = args.num_gpu_blocks if i < args.num_layers else self.num_extra_layer_gpu_blocks
-
-            self.gpu_cache_kvs[f"key_caches_{i}_rank{rank}_device{device}"] = paddle.full(
-                shape=[
-                    num_gpu_blocks,
-                    args.kv_num_head,
-                    args.block_size,
-                    args.head_dim,
-                ],
-                fill_value=0,
-                dtype=cache_type,
-            )
-            self.gpu_cache_k_tensors.append(self.gpu_cache_kvs[f"key_caches_{i}_rank{rank}_device{device}"])
-            self.gpu_cache_kvs[f"value_caches_{i}_rank{rank}_device{device}"] = paddle.full(
-                shape=[
-                    num_gpu_blocks,
-                    args.kv_num_head,
-                    args.block_size,
-                    args.head_dim,
-                ],
-                fill_value=0,
-                dtype=cache_type,
-            )
-            self.gpu_cache_v_tensors.append(self.gpu_cache_kvs[f"value_caches_{i}_rank{rank}_device{device}"])
-
-            set_data_ipc(
-                self.gpu_cache_kvs[f"key_caches_{i}_rank{rank}_device{device}"],
-                f"key_caches_{i}_rank{rank}.device{device}",
-            )
-            set_data_ipc(
-                self.gpu_cache_kvs[f"value_caches_{i}_rank{rank}_device{device}"],
-                f"value_caches_{i}_rank{rank}.device{device}",
-            )
-        cache_kv_size_byte = sum([tmp.numel() * 1 for key, tmp in self.gpu_cache_kvs.items()])
-        logger.info(f"device :{self.device}")
-        logger.info(f"cache_kv_size_byte : {cache_kv_size_byte}")
-        logger.info(f"done init cache (full) gmem alloc : {paddle.device.cuda.memory_allocated()}")
-
-        paddle.set_device("cpu")
-        self.k_dst_ptrs = []
-        self.v_dst_ptrs = []
-        for i in range(args.num_layers + self.num_extra_layers):
-            self.cpu_cache_kvs[f"key_caches_{i}_rank{rank}"] = cuda_host_alloc(
-                args.num_cpu_blocks * args.bytes_per_layer_per_block
-            )
-            self.k_dst_ptrs.append(self.cpu_cache_kvs[f"key_caches_{i}_rank{rank}"])
-            self.cpu_cache_kvs[f"value_caches_{i}_rank{rank}"] = cuda_host_alloc(
-                args.num_cpu_blocks * args.bytes_per_layer_per_block
-            )
-            self.v_dst_ptrs.append(self.cpu_cache_kvs[f"value_caches_{i}_rank{rank}"])
-
         cache_ready_signal_data = np.zeros(shape=[args.mp_num], dtype=np.int32)
         self.cache_ready_signal = IPCSignal(
             name="cache_ready_signal",
             array=cache_ready_signal_data,
             dtype=np.int32,
-            suffix=args.engine_pid,
+            suffix=self.engine_pid,
+            create=False,
+        )
+        swap_space_ready_data = np.zeros(shape=[args.mp_num], dtype=np.int32)
+        self.swap_space_ready_signal = IPCSignal(
+            name="swap_space_ready_signal",
+            array=swap_space_ready_data,
+            dtype=np.int32,
+            suffix=self.engine_pid,
             create=False,
         )
-        self.cache_ready_signal.value[self.rank] = 1
+
+        self.num_cpu_blocks = args.num_cpu_blocks
+
+        self._init_cpu_cache(args)
+        self._init_gpu_cache(args)
 
         paddle.set_device(f"gpu:{device}")
         if args.enable_splitwise:
@@ -232,6 +196,72 @@ def __init__(self, args):
             create=False,
         )
 
+        threading.Thread(target=self.clear_or_update_caches, args=[args], daemon=True).start()
+
+    def _init_gpu_cache(self, args):
+
+        if not args.create_cache_tensor:
+            logger.info("Waiting for runners to create kv cache.")
+            while self.cache_ready_signal.value[self.rank] != 1:
+                time.sleep(1)
+            logger.info("OK! Stop waiting.")
+
+        logger.info("Initializing kv cache for all layers.")
+        paddle.set_device(f"gpu:{self.device}")
+        for i in range(args.num_layers + self.num_extra_layers):
+            num_gpu_blocks = args.num_gpu_blocks if i < args.num_layers else self.num_extra_layer_gpu_blocks
+            cache_shape = [num_gpu_blocks, args.kv_num_head, args.block_size, args.head_dim]
+            key_name = f"key_caches_{i}_rank{self.rank}.device{self.device}"
+            val_name = f"value_caches_{i}_rank{self.rank}.device{self.device}"
+
+            if args.create_cache_tensor:
+                logger.info(f"..creating kv cache for layer {i}: {cache_shape}")
+                key_cache = paddle.full(shape=cache_shape, fill_value=0, dtype=args.cache_dtype)
+                val_cache = paddle.full(shape=cache_shape, fill_value=0, dtype=args.cache_dtype)
+                set_data_ipc(key_cache, key_name)
+                set_data_ipc(val_cache, val_name)
+            else:
+                logger.info(f"..attaching kv cache for layer {i}: {cache_shape}")
+                key_cache = paddle.empty(shape=[], dtype=args.cache_dtype)
+                val_cache = paddle.empty(shape=[], dtype=args.cache_dtype)
+                key_cache = share_external_data(key_cache, key_name, cache_shape)
+                val_cache = share_external_data(val_cache, val_name, cache_shape)
+
+            self.gpu_cache_kvs[key_name] = key_cache
+            self.gpu_cache_kvs[val_name] = val_cache
+            self.gpu_cache_k_tensors.append(self.gpu_cache_kvs[key_name])
+            self.gpu_cache_v_tensors.append(self.gpu_cache_kvs[val_name])
+
+        if args.create_cache_tensor:
+            logger.info("✅ kv cache is ready!")
+            self.cache_ready_signal.value[self.rank] = 1
+
+        cache_kv_size_byte = sum([tmp.numel() * 1 for key, tmp in self.gpu_cache_kvs.items()])
+        logger.info(f"device :{self.device}")
+        logger.info(f"cache_kv_size_byte : {cache_kv_size_byte}")
+        logger.info(f"done init cache (full) gmem alloc : {paddle.device.cuda.memory_allocated()}")
+
+    def _init_cpu_cache(self, args):
+        if args.num_cpu_blocks == 0:
+            logger.info("💡 no swap space (cpu cache) is specified.")
+            self.swap_space_ready_signal.value[self.rank] = 1
+            return
+        logger.info("Initializing swap space (cpu cache) for all layers.")
+        paddle.set_device("cpu")
+        self.k_dst_ptrs = []
+        self.v_dst_ptrs = []
+        for i in range(args.num_layers + self.num_extra_layers):
+            key_name = f"key_caches_{i}_rank{self.rank}"
+            val_name = f"value_caches_{i}_rank{self.rank}"
+            need_to_allocate_bytes = args.num_cpu_blocks * args.bytes_per_layer_per_block
+            logger.info(f"..creating cpu cache for layer {i}: {2 * need_to_allocate_bytes / 1024 ** 3:.2f}GB")
+            self.cpu_cache_kvs[key_name] = cuda_host_alloc(need_to_allocate_bytes)
+            self.k_dst_ptrs.append(self.cpu_cache_kvs[key_name])
+            self.cpu_cache_kvs[val_name] = cuda_host_alloc(need_to_allocate_bytes)
+            self.v_dst_ptrs.append(self.cpu_cache_kvs[val_name])
+        logger.info("✅ swap space (cpu cache) is ready!")
+        self.swap_space_ready_signal.value[self.rank] = 1
+
     def _do_swap_to_cpu_task(
         self,
         swap_node_ids,
@@ -429,6 +459,67 @@ def _transfer_data(
             transfer_task_id,
         )
 
+    def clear_or_update_caches(self, args):
+        logger.info("Start a thread to clear/restore kv cache when model weights are cleared/updated.")
+        logger.info(f"FD_ENABLE_SWAP_SPACE_CLEARING={envs.FD_ENABLE_SWAP_SPACE_CLEARING}")
+        kv_cache_status = np.zeros([1], dtype=np.int32)
+        kv_cache_status_signal = IPCSignal(
+            name="kv_cache_status",
+            array=kv_cache_status,
+            dtype=np.int32,
+            suffix=self.engine_pid,
+            create=False,
+        )
+        while True:
+            if kv_cache_status_signal.value[0] == KVCacheStatus.CLEARING:
+                try:
+                    if envs.FD_ENABLE_SWAP_SPACE_CLEARING:
+                        paddle.set_device("cpu")
+                        for ptrs in self.k_dst_ptrs + self.v_dst_ptrs:
+                            cuda_host_free(ptrs)
+                        self.cpu_cache_kvs.clear()
+                        self.k_dst_ptrs.clear()
+                        self.v_dst_ptrs.clear()
+                        gc.collect()
+                        # reset swap_space_ready_signal
+                        self.swap_space_ready_signal.value[self.rank] = 0
+                        while np.sum(self.swap_space_ready_signal.value) != 0:
+                            time.sleep(0.1)
+
+                    paddle.set_device(f"gpu:{self.device}")
+                    for name, tensor in self.gpu_cache_kvs.items():
+                        unset_data_ipc(tensor, name, True, False)
+                    self.gpu_cache_kvs.clear()
+                    self.gpu_cache_k_tensors.clear()
+                    self.gpu_cache_v_tensors.clear()
+                    # reset cache_ready_signal
+                    self.cache_ready_signal.value[self.rank] = 0
+                    if np.sum(self.cache_ready_signal.value) == 0:
+                        time.sleep(0.1)
+
+                    kv_cache_status_signal.value[0] = KVCacheStatus.CLEARED
+
+                except Exception as e:
+                    logger.error(f"Failed to clear caches: {e}")
+
+            elif kv_cache_status_signal.value[0] == KVCacheStatus.UPDATING:
+                try:
+                    if envs.FD_ENABLE_SWAP_SPACE_CLEARING:
+                        self._init_cpu_cache(args)
+                        while np.sum(self.swap_space_ready_signal.value) != args.mp_num:
+                            time.sleep(0.1)
+
+                    self._init_gpu_cache(args)
+                    while np.sum(self.cache_ready_signal.value) != args.mp_num:
+                        time.sleep(0.1)
+
+                    kv_cache_status_signal.value[0] = KVCacheStatus.NORMAL
+
+                except Exception as e:
+                    logger.error(f"Failed to restore caches: {e}")
+
+            time.sleep(0.1)
+
 
 def main():
     """