Key difference from non-MP plugins: In MP mode the LMCACHE_RUNTIME_PLUGIN_CONFIG environment variable carries an aggregated JSON dict with sections like mp_config, storage_manager_config, and obs_config — rather than a single LMCacheEngineConfig JSON.

Design

For architecture details, component diagrams, and data flow, see docs/design/v1/multiprocess/mp_runtime_plugin.md.

Files

File	Language	Description
`mp_plugin.py`	Python	Parses the aggregated MP config and runs a periodic status reporter
`mp_heartbeat.sh`	Bash	Extracts config fields via `jq` and runs a heartbeat loop

Environment Variables

Plugins receive the following environment variables:

Variable	Description
`LMCACHE_RUNTIME_PLUGIN_CONFIG`	Aggregated JSON config (see below)

Note: Unlike the non-MP (vLLM integration) mode, the MP server does not have multiple roles (e.g. SCHEDULER, WORKER). All plugins run in the single MP server process. The filename prefix-based role filtering has no effect in MP mode.

Config JSON Structure (MP mode)

{
  "mp_config": {
    "host": "localhost",
    "port": 5555,
    "chunk_size": 256,
    "max_workers": 1,
    "hash_algorithm": "blake3",
    "engine_type": "default",
    "runtime_plugin_locations": ["examples/mp_runtime_plugins/"]
  },
  "storage_manager_config": {
    "l1_manager_config": {
      "memory_config": {
        "size_in_bytes": 10737418240,
        "use_lazy": true
      }
    },
    "eviction_config": {
      "eviction_policy": "LRU",
      "trigger_watermark": 0.8,
      "eviction_ratio": 0.2
    }
  },
  "obs_config": {
    "enabled": true,
    "metrics_enabled": true,
    "logging_enabled": true,
    "tracing_enabled": false
  }
}

Quick Start

Launch the LMCache MP server with the plugin directory:

python -m lmcache.v1.multiprocess.server \
    --host localhost --port 5555 \
    --l1-size-gb 10 \
    --eviction-policy LRU \
    --runtime-plugin-locations examples/mp_runtime_plugins/

You should see plugin output in the server logs:

[mp_plugin] Started
[mp_plugin] MP server: host=localhost  port=5555  chunk_size=256
[mp_plugin] Storage: L1=10.0GB  eviction=LRU  watermark=0.8
[mp_plugin] heartbeat #0