Merge PDLB (Prefill-Decode Load Balancer) into SGLang Router (#7096)

sgl-router/py_src/sglang_router/router.py

@@ -15,6 +15,7 @@ class Router:
             - PolicyType.Random: Randomly select workers
             - PolicyType.RoundRobin: Distribute requests in round-robin fashion
             - PolicyType.CacheAware: Distribute requests based on cache state and load balance
+            - PolicyType.PowerOfTwo: Select best of two random workers based on load (PD mode only)
         host: Host address to bind the router server. Default: '127.0.0.1'
         port: Port number to bind the router server. Default: 3001
         worker_startup_timeout_secs: Timeout in seconds for worker startup. Default: 300
@@ -28,7 +29,7 @@ class Router:
             AND max_load > min_load * rel_threshold. Otherwise, use cache aware. Default: 1.0001
         eviction_interval_secs: Interval in seconds between cache eviction operations in cache-aware
             routing. Default: 60
-        max_payload_size: Maximum payload size in bytes. Default: 4MB
+        max_payload_size: Maximum payload size in bytes. Default: 256MB
         max_tree_size: Maximum size of the approximation tree for cache-aware routing. Default: 2^24
         verbose: Enable verbose logging. Default: False
         log_dir: Directory to store log files. If None, logs are only output to console. Default: None
@@ -42,6 +43,9 @@ class Router:
             watches pods across all namespaces (requires cluster-wide permissions). Default: None
         prometheus_port: Port to expose Prometheus metrics. Default: None
         prometheus_host: Host address to bind the Prometheus metrics server. Default: None
+        pd_disaggregated: Enable PD (Prefill-Decode) disaggregated mode. Default: False
+        prefill_urls: List of (url, bootstrap_port) tuples for prefill servers (PD mode only)
+        decode_urls: List of URLs for decode servers (PD mode only)
     """
 
     def __init__(
@@ -57,7 +61,7 @@ class Router:
         balance_rel_threshold: float = 1.0001,
         eviction_interval_secs: int = 60,
         max_tree_size: int = 2**24,
-        max_payload_size: int = 4 * 1024 * 1024,  # 4MB
+        max_payload_size: int = 256 * 1024 * 1024,  # 256MB
         verbose: bool = False,
         log_dir: Optional[str] = None,
         service_discovery: bool = False,
@@ -66,6 +70,9 @@ class Router:
         service_discovery_namespace: Optional[str] = None,
         prometheus_port: Optional[int] = None,
         prometheus_host: Optional[str] = None,
+        pd_disaggregated: bool = False,
+        prefill_urls: Optional[List[tuple]] = None,
+        decode_urls: Optional[List[str]] = None,
     ):
         if selector is None:
             selector = {}
@@ -91,6 +98,9 @@ class Router:
             service_discovery_namespace=service_discovery_namespace,
             prometheus_port=prometheus_port,
             prometheus_host=prometheus_host,
+            pd_disaggregated=pd_disaggregated,
+            prefill_urls=prefill_urls,
+            decode_urls=decode_urls,
         )
 
     def start(self) -> None: