[mem_cache] Clean up unified allocator leftovers (#38103)

python/sglang/srt/environ.py

@@ -545,6 +545,9 @@ class Envs:
     # Periodically log lazy-compaction stats per sub-pool (observability only).
     SGLANG_LOG_LAZY_COMPACTION_STATS = EnvBool(False)
     SGLANG_LOG_LAZY_COMPACTION_STATS_INTERVAL_SEC = EnvInt(30)
+    # Per-call move cap on a non-urgent lazy-compaction flush, so a large
+    # backlog cannot stall the scheduler loop; urgent flushes are uncapped.
+    SGLANG_LAZY_COMPACTION_MAX_MOVES_PER_CALL = EnvInt(4096)
     # HND KV layout folds (page, head) into one paged index for per-kv-head sparse
     # page tables (DP attn); paged backends like trtllm_mha consume it directly.
     SGLANG_USE_HND_KVCACHE = EnvBool(False)

python/sglang/srt/mem_cache/allocator/base.py

@@ -122,11 +122,9 @@ class BaseTokenToKVPoolAllocator(abc.ABC):
         return kv_indices
 
     def get_cpu_copy(self, indices, mamba_indices=None):
-        # FIXME: reuse the get_cpu_copy after paged allocator is implemented
         raise NotImplementedError()
 
     def load_cpu_copy(self, kv_cache_cpu, indices, mamba_indices=None):
-        # FIXME: reuse the load_cpu_copy after paged allocator is implemented
         raise NotImplementedError()
 
     def alloc_extend(self, *args, **kwargs):

python/sglang/srt/mem_cache/allocator/hisparse.py

@@ -472,7 +472,8 @@ class DeepSeekV4HiSparseTokenToKVPoolAllocator(BaseTokenToKVPoolAllocator):
         self.hisparse_attn_allocator.free(buffer_indices[buffer_indices > 0])
 
     def get_last_loc_compressed(self, last_locs: torch.Tensor):
-        return (last_locs - 3) // self.compress_ratio
+        # Last complete C4 block of a prefix of last_loc + 1 tokens; -1 stays -1.
+        return (last_locs - (self.compress_ratio - 1)) // self.compress_ratio
 
     def get_last_loc_hisparse_device(self, last_locs: torch.Tensor):
         return self.hisparse_kvcache._translate_loc_to_hisparse_device(

python/sglang/srt/mem_cache/allocator/paged.py

@@ -15,11 +15,6 @@ limitations under the License.
 
 from __future__ import annotations
 
-"""
-Page-aligned memory pool.
-"""
-
-
 from typing import TYPE_CHECKING
 
 import torch

python/sglang/srt/mem_cache/allocator/unified_hybrid_swa.py

@@ -878,6 +878,7 @@ class UnifiedMambaSWATokenToKVPoolAllocator(UnifiedSWATokenToKVPoolAllocator):
         at once, so re-check the JOINT gate instead of the per-side shortfall."""
         from sglang.srt.mem_cache.common import evict_from_tree_cache
 
+        # Arbitrary retry bound; a round that frees nothing ends the loop anyway.
         for _ in range(4):
             before = self.available_size()
             if before >= num_tokens:

python/sglang/srt/mem_cache/allocator/unified_mamba.py

@@ -306,11 +306,6 @@ class UnifiedMambaTokenToKVPoolAllocator(BaseTokenToKVPoolAllocator):
             self.full_attn_allocator.clear_inverse_history()
             self.mamba_allocator.clear_inverse_history()
 
-    def clear(self) -> None:
-        self.full_attn_allocator.clear()
-        self.mamba_allocator.clear()
-        self.free_group = None
-
     def free_segment(self, free_index: torch.Tensor, *, start_pos: int) -> None:
         """Fixed-shape counterpart of `free()`; see `MultiEndedAllocator._page_reps`.
         The mamba sub-pool is slot-granular and untouched by a token free."""

python/sglang/srt/mem_cache/allocator/unified_sub_pool.py

@@ -361,8 +361,8 @@ class MultiEndedAllocator(BaseTokenToKVPoolAllocator):
 
         # Per-call move cap on NON-urgent `_flush`: bounds work per `on_idle()` so
         # a large backlog doesn't block ZMQ IPC. Urgent retries are uncapped.
-        self._lazy_max_moves_per_call = int(
-            os.environ.get("SGLANG_LAZY_COMPACTION_MAX_MOVES_PER_CALL", "4096")
+        self._lazy_max_moves_per_call = (
+            envs.SGLANG_LAZY_COMPACTION_MAX_MOVES_PER_CALL.get()
         )
 
         # Epoch-keyed memos for the capacity views: pure between mutations, but