[router] adds reasoning parser pooling and thread-safe (#9360)

sgl-router/src/reasoning_parser/factory.rs

 // Factory and registry for creating model-specific reasoning parsers.
+// Now with parser pooling support for efficient reuse across requests.
 
 use std::collections::HashMap;
-use std::sync::{Arc, RwLock};
+use std::sync::{Arc, Mutex, RwLock};
 
 use crate::reasoning_parser::parsers::{
     BaseReasoningParser, DeepSeekR1Parser, KimiParser, Qwen3Parser, QwenThinkingParser,
 };
 use crate::reasoning_parser::traits::{ParseError, ParserConfig, ReasoningParser};
 
+/// Type alias for pooled parser instances.
+pub type PooledParser = Arc<Mutex<Box<dyn ReasoningParser>>>;
+
 /// Type alias for parser creator functions.
 type ParserCreator = Arc<dyn Fn() -> Box<dyn ReasoningParser> + Send + Sync>;
 
-/// Registry for model-specific parsers.
+/// Registry for model-specific parsers with pooling support.
 #[derive(Clone)]
 pub struct ParserRegistry {
-    parsers: Arc<RwLock<HashMap<String, ParserCreator>>>,
+    /// Creator functions for parsers (used when pool is empty)
+    creators: Arc<RwLock<HashMap<String, ParserCreator>>>,
+    /// Pooled parser instances for reuse
+    pool: Arc<RwLock<HashMap<String, PooledParser>>>,
+    /// Model pattern to parser name mappings
     patterns: Arc<RwLock<Vec<(String, String)>>>, // (pattern, parser_name)
 }
 
@@ -22,7 +30,8 @@ impl ParserRegistry {
     /// Create a new empty registry.
     pub fn new() -> Self {
         Self {
-            parsers: Arc::new(RwLock::new(HashMap::new())),
+            creators: Arc::new(RwLock::new(HashMap::new())),
+            pool: Arc::new(RwLock::new(HashMap::new())),
             patterns: Arc::new(RwLock::new(Vec::new())),
         }
     }
@@ -32,8 +41,8 @@ impl ParserRegistry {
     where
         F: Fn() -> Box<dyn ReasoningParser> + Send + Sync + 'static,
     {
-        let mut parsers = self.parsers.write().unwrap();
-        parsers.insert(name.to_string(), Arc::new(creator));
+        let mut creators = self.creators.write().unwrap();
+        creators.insert(name.to_string(), Arc::new(creator));
     }
 
     /// Register a model pattern to parser mapping.
@@ -43,13 +52,53 @@ impl ParserRegistry {
         patterns.push((pattern.to_string(), parser_name.to_string()));
     }
 
-    /// Get a parser by exact name.
+    /// Get a pooled parser by exact name.
+    /// Returns a shared parser instance from the pool, creating one if needed.
+    pub fn get_pooled_parser(&self, name: &str) -> Option<PooledParser> {
+        // First check if we have a pooled instance
+        {
+            let pool = self.pool.read().unwrap();
+            if let Some(parser) = pool.get(name) {
+                return Some(Arc::clone(parser));
+            }
+        }
+
+        // If not in pool, create one and add to pool
+        let creators = self.creators.read().unwrap();
+        if let Some(creator) = creators.get(name) {
+            let parser = Arc::new(Mutex::new(creator()));
+
+            // Add to pool for future use
+            let mut pool = self.pool.write().unwrap();
+            pool.insert(name.to_string(), Arc::clone(&parser));
+
+            Some(parser)
+        } else {
+            None
+        }
+    }
+
+    /// Get a parser by exact name (creates new instance, not pooled).
+    /// Use this for compatibility or when you need a fresh instance.
     pub fn get_parser(&self, name: &str) -> Option<Box<dyn ReasoningParser>> {
-        let parsers = self.parsers.read().unwrap();
-        parsers.get(name).map(|creator| creator())
+        let creators = self.creators.read().unwrap();
+        creators.get(name).map(|creator| creator())
+    }
+
+    /// Find a pooled parser for a given model ID by pattern matching.
+    pub fn find_pooled_parser_for_model(&self, model_id: &str) -> Option<PooledParser> {
+        let patterns = self.patterns.read().unwrap();
+        let model_lower = model_id.to_lowercase();
+
+        for (pattern, parser_name) in patterns.iter() {
+            if model_lower.contains(&pattern.to_lowercase()) {
+                return self.get_pooled_parser(parser_name);
+            }
+        }
+        None
     }
 
-    /// Find a parser for a given model ID by pattern matching.
+    /// Find a parser for a given model ID by pattern matching (creates new instance).
     pub fn find_parser_for_model(&self, model_id: &str) -> Option<Box<dyn ReasoningParser>> {
         let patterns = self.patterns.read().unwrap();
         let model_lower = model_id.to_lowercase();
@@ -61,6 +110,13 @@ impl ParserRegistry {
         }
         None
     }
+
+    /// Clear the parser pool, forcing new instances to be created.
+    /// Useful for testing or when parsers need to be reset globally.
+    pub fn clear_pool(&self) {
+        let mut pool = self.pool.write().unwrap();
+        pool.clear();
+    }
 }
 
 impl Default for ParserRegistry {
@@ -70,6 +126,7 @@ impl Default for ParserRegistry {
 }
 
 /// Factory for creating reasoning parsers based on model type.
+#[derive(Clone)]
 pub struct ParserFactory {
     registry: ParserRegistry,
 }
@@ -109,8 +166,39 @@ impl ParserFactory {
         Self { registry }
     }
 
-    /// Create a parser for the given model ID.
-    /// Returns a no-op parser if model is not recognized.
+    /// Get a pooled parser for the given model ID.
+    /// Returns a shared instance that can be used concurrently.
+    /// Falls back to a passthrough parser if model is not recognized.
+    pub fn get_pooled(&self, model_id: &str) -> PooledParser {
+        // First try to find by pattern
+        if let Some(parser) = self.registry.find_pooled_parser_for_model(model_id) {
+            return parser;
+        }
+
+        // Fall back to no-op parser (get or create passthrough in pool)
+        self.registry
+            .get_pooled_parser("passthrough")
+            .unwrap_or_else(|| {
+                // Register passthrough if not already registered
+                self.registry.register_parser("passthrough", || {
+                    let config = ParserConfig {
+                        think_start_token: "".to_string(),
+                        think_end_token: "".to_string(),
+                        stream_reasoning: true,
+                        max_buffer_size: 65536,
+                        initial_in_reasoning: false,
+                    };
+                    Box::new(
+                        BaseReasoningParser::new(config).with_model_type("passthrough".to_string()),
+                    )
+                });
+                self.registry.get_pooled_parser("passthrough").unwrap()
+            })
+    }
+
+    /// Create a new parser instance for the given model ID.
+    /// Returns a fresh instance (not pooled).
+    /// Use this when you need an isolated parser instance.
     pub fn create(&self, model_id: &str) -> Result<Box<dyn ReasoningParser>, ParseError> {
         // First try to find by pattern
         if let Some(parser) = self.registry.find_parser_for_model(model_id) {
@@ -134,6 +222,12 @@ impl ParserFactory {
     pub fn registry(&self) -> &ParserRegistry {
         &self.registry
     }
+
+    /// Clear the parser pool.
+    /// Useful for testing or when parsers need to be reset globally.
+    pub fn clear_pool(&self) {
+        self.registry.clear_pool();
+    }
 }
 
 impl Default for ParserFactory {
@@ -195,4 +289,267 @@ mod tests {
         assert_eq!(step3.model_type(), "deepseek_r1");
         assert_eq!(glm45.model_type(), "qwen3");
     }
+
+    #[test]
+    fn test_pooled_parser_reuse() {
+        let factory = ParserFactory::new();
+
+        // Get the same parser twice - should be the same instance
+        let parser1 = factory.get_pooled("deepseek-r1");
+        let parser2 = factory.get_pooled("deepseek-r1");
+
+        // Both should point to the same Arc
+        assert!(Arc::ptr_eq(&parser1, &parser2));
+
+        // Different models should get different parsers
+        let parser3 = factory.get_pooled("qwen3");
+        assert!(!Arc::ptr_eq(&parser1, &parser3));
+    }
+
+    #[test]
+    fn test_pooled_parser_concurrent_access() {
+        use std::thread;
+
+        let factory = ParserFactory::new();
+        let parser = factory.get_pooled("deepseek-r1");
+
+        // Spawn multiple threads that use the same parser
+        let mut handles = vec![];
+
+        for i in 0..3 {
+            let parser_clone = Arc::clone(&parser);
+            let handle = thread::spawn(move || {
+                let mut parser = parser_clone.lock().unwrap();
+                let input = format!("thread {} reasoning</think>answer", i);
+                let result = parser.detect_and_parse_reasoning(&input).unwrap();
+                assert_eq!(result.normal_text, "answer");
+                assert!(result.reasoning_text.contains("reasoning"));
+            });
+            handles.push(handle);
+        }
+
+        // Wait for all threads to complete
+        for handle in handles {
+            handle.join().unwrap();
+        }
+    }
+
+    #[test]
+    fn test_pool_clearing() {
+        let factory = ParserFactory::new();
+
+        // Get a pooled parser
+        let parser1 = factory.get_pooled("deepseek-r1");
+
+        // Clear the pool
+        factory.clear_pool();
+
+        // Get another parser - should be a new instance
+        let parser2 = factory.get_pooled("deepseek-r1");
+
+        // They should be different instances (different Arc pointers)
+        assert!(!Arc::ptr_eq(&parser1, &parser2));
+    }
+
+    #[test]
+    fn test_passthrough_parser_pooling() {
+        let factory = ParserFactory::new();
+
+        // Unknown models should get passthrough parser
+        let parser1 = factory.get_pooled("unknown-model-1");
+        let parser2 = factory.get_pooled("unknown-model-2");
+
+        // Both should use the same passthrough parser instance
+        assert!(Arc::ptr_eq(&parser1, &parser2));
+
+        // Verify it's actually a passthrough parser
+        let parser = parser1.lock().unwrap();
+        assert_eq!(parser.model_type(), "passthrough");
+    }
+
+    #[test]
+    fn test_high_concurrency_parser_access() {
+        use std::sync::atomic::{AtomicUsize, Ordering};
+        use std::thread;
+        use std::time::Instant;
+
+        let factory = ParserFactory::new();
+        let num_threads = 100;
+        let requests_per_thread = 50;
+        let models = vec!["deepseek-r1", "qwen3", "kimi", "qwen3-thinking"];
+
+        // Track successful operations
+        let success_count = Arc::new(AtomicUsize::new(0));
+        let error_count = Arc::new(AtomicUsize::new(0));
+
+        let start = Instant::now();
+        let mut handles = vec![];
+
+        for thread_id in 0..num_threads {
+            let factory = factory.clone();
+            let models = models.clone();
+            let success_count = Arc::clone(&success_count);
+            let error_count = Arc::clone(&error_count);
+
+            let handle = thread::spawn(move || {
+                for request_id in 0..requests_per_thread {
+                    // Rotate through different models
+                    let model = &models[(thread_id + request_id) % models.len()];
+                    let parser = factory.get_pooled(model);
+
+                    // Use blocking lock - this is the realistic scenario
+                    // In production, requests would wait for the parser to be available
+                    // Handle poisoned locks gracefully
+                    let mut p = match parser.lock() {
+                        Ok(guard) => guard,
+                        Err(_poisoned) => {
+                            // Lock was poisoned by a panicking thread
+                            // In production, we might want to recreate the parser
+                            // For testing, we'll just skip this iteration
+                            error_count.fetch_add(1, Ordering::Relaxed);
+                            continue;
+                        }
+                    };
+
+                    // Simulate realistic parsing work with substantial text
+                    // Typical reasoning can be 500-5000 tokens
+                    let reasoning_text = format!(
+                        "Thread {} is processing request {}. Let me think through this step by step. \
+                        First, I need to understand the problem. The problem involves analyzing data \
+                        and making calculations. Let me break this down: \n\
+                        1. Initial analysis shows that we have multiple variables to consider. \
+                        2. The data suggests a pattern that needs further investigation. \
+                        3. Computing the values: {} * {} = {}. \
+                        4. Cross-referencing with previous results indicates consistency. \
+                        5. The mathematical proof follows from the axioms... \
+                        6. Considering edge cases and boundary conditions... \
+                        7. Validating against known constraints... \
+                        8. The conclusion follows logically from premises A, B, and C. \
+                        This reasoning chain demonstrates the validity of our approach.",
+                        thread_id, request_id, thread_id, request_id, thread_id * request_id
+                    );
+
+                    let answer_text = format!(
+                        "Based on my analysis, the answer for thread {} request {} is: \
+                        The solution involves multiple steps as outlined in the reasoning. \
+                        The final result is {} with confidence level high. \
+                        This conclusion is supported by rigorous mathematical analysis \
+                        and has been validated against multiple test cases. \
+                        The implementation should handle edge cases appropriately.",
+                        thread_id,
+                        request_id,
+                        thread_id * request_id
+                    );
+
+                    let input = format!("<think>{}</think>{}", reasoning_text, answer_text);
+
+                    match p.detect_and_parse_reasoning(&input) {
+                        Ok(result) => {
+                            // Verify parsing worked correctly with substantial content
+                            // Note: Some parsers with stream_reasoning=true won't accumulate reasoning text
+                            assert!(result
+                                .normal_text
+                                .contains(&format!("thread {}", thread_id)));
+
+                            // For parsers that accumulate reasoning (stream_reasoning=false)
+                            // the reasoning_text should be populated
+                            if !result.reasoning_text.is_empty() {
+                                assert!(result
+                                    .reasoning_text
+                                    .contains(&format!("Thread {}", thread_id)));
+                                assert!(result.reasoning_text.len() > 500); // Ensure substantial reasoning
+                            }
+
+                            // Normal text should always be present
+                            assert!(result.normal_text.len() > 100); // Ensure substantial answer
+                            success_count.fetch_add(1, Ordering::Relaxed);
+                        }
+                        Err(e) => {
+                            eprintln!("Parse error: {:?}", e);
+                            error_count.fetch_add(1, Ordering::Relaxed);
+                        }
+                    }
+
+                    // Explicitly drop the lock to release it quickly
+                    drop(p);
+                }
+            });
+            handles.push(handle);
+        }
+
+        // Wait for all threads
+        for handle in handles {
+            handle.join().unwrap();
+        }
+
+        let duration = start.elapsed();
+        let total_requests = num_threads * requests_per_thread;
+        let successes = success_count.load(Ordering::Relaxed);
+        let errors = error_count.load(Ordering::Relaxed);
+
+        // Print stats for debugging
+        println!(
+            "High concurrency test: {} threads, {} requests each",
+            num_threads, requests_per_thread
+        );
+        println!(
+            "Completed in {:?}, {} successes, {} errors",
+            duration, successes, errors
+        );
+        println!(
+            "Throughput: {:.0} requests/sec",
+            (total_requests as f64) / duration.as_secs_f64()
+        );
+
+        // All requests should succeed
+        assert_eq!(successes, total_requests);
+        assert_eq!(errors, 0);
+
+        // Performance check: should handle at least 1000 req/sec
+        let throughput = (total_requests as f64) / duration.as_secs_f64();
+        assert!(
+            throughput > 1000.0,
+            "Throughput too low: {:.0} req/sec",
+            throughput
+        );
+    }
+
+    #[test]
+    fn test_concurrent_pool_modifications() {
+        use std::thread;
+
+        let factory = ParserFactory::new();
+        let mut handles = vec![];
+
+        // Thread 1: Continuously get parsers
+        let factory1 = factory.clone();
+        handles.push(thread::spawn(move || {
+            for _ in 0..100 {
+                let _parser = factory1.get_pooled("deepseek-r1");
+            }
+        }));
+
+        // Thread 2: Continuously clear pool
+        let factory2 = factory.clone();
+        handles.push(thread::spawn(move || {
+            for _ in 0..10 {
+                factory2.clear_pool();
+                thread::sleep(std::time::Duration::from_micros(100));
+            }
+        }));
+
+        // Thread 3: Get different parsers
+        let factory3 = factory.clone();
+        handles.push(thread::spawn(move || {
+            for i in 0..100 {
+                let models = ["qwen3", "kimi", "unknown"];
+                let _parser = factory3.get_pooled(models[i % 3]);
+            }
+        }));
+
+        // Wait for all threads - should not deadlock or panic
+        for handle in handles {
+            handle.join().unwrap();
+        }
+    }
 }

sgl-router/src/reasoning_parser/mod.rs

@@ -2,7 +2,7 @@ pub mod factory;
 pub mod parsers;
 pub mod traits;
 
-pub use factory::{ParserFactory, ParserRegistry};
+pub use factory::{ParserFactory, ParserRegistry, PooledParser};
 pub use parsers::{
     BaseReasoningParser, DeepSeekR1Parser, KimiParser, Qwen3Parser, QwenThinkingParser,
 };