fix: prevent unbounded memory leak during concurrent validation under…

src/jvmMain/kotlin/controller/validation/ValidationServiceFactoryImpl.kt

@@ -16,12 +16,18 @@ import kotlin.collections.ArrayList
 class ValidationServiceFactoryImpl : ValidationServiceFactory {
     private val validationServiceConfig: ValidationServiceConfig = ValidatorApplicationConfig.validationServiceConfig
     private var sessionCacheFactory: SessionCacheFactory = SessionCacheFactoryImpl()
+    @Volatile
     private var validationService: ValidationService
     private var presets: List<Preset>
 
+    private val reloadLock = java.util.concurrent.locks.ReentrantLock()
+    private var lastReloadTime: Long = 0
+    private val RELOAD_COOLDOWN_MS = java.util.concurrent.TimeUnit.MINUTES.toMillis(5)
+
     init {
         presets = loadPresets();
         validationService = createValidationServiceInstance();
+        lastReloadTime = System.currentTimeMillis()
     }
 
     private fun createValidationServiceInstance(): ValidationService {
@@ -72,13 +78,30 @@ class ValidationServiceFactoryImpl : ValidationServiceFactory {
     }
 
     override fun getValidationService() : ValidationService {
-        if (java.lang.Runtime.getRuntime().freeMemory() < validationServiceConfig.engineReloadThreshold) {
-            println(
-                "Free memory ${
-                    java.lang.Runtime.getRuntime().freeMemory()
-                } is less than ${validationServiceConfig.engineReloadThreshold}. Re-initializing validationService"
-            );
-            validationService = createValidationServiceInstance();
+        val freeMemory = java.lang.Runtime.getRuntime().freeMemory()
+        if (freeMemory < validationServiceConfig.engineReloadThreshold) {
+            val now = System.currentTimeMillis()
+            // Try to acquire lock. If we can't, another thread is already reloading it, so just return the existing one.
+            if (reloadLock.tryLock()) {
+                try {
+                    // Double check time and memory inside the lock
+                    if (java.lang.Runtime.getRuntime().freeMemory() < validationServiceConfig.engineReloadThreshold &&
+                        (now - lastReloadTime) > RELOAD_COOLDOWN_MS) {
+
+                        println(
+                            "Free memory ${
+                                java.lang.Runtime.getRuntime().freeMemory()
+                            } is less than ${validationServiceConfig.engineReloadThreshold} and cooldown passed. Re-initializing validationService"
+                        );
+                        validationService = createValidationServiceInstance();
+                        lastReloadTime = System.currentTimeMillis()
+                    }
+                } finally {
+                    reloadLock.unlock()
+                }
+            } else {
+                println("Memory is low ($freeMemory), but another thread is currently re-initializing the engine. Skipping.")
+            }
         }
         return validationService;
     }