[UR][L0] event pool leak fix

Addresses event pool leak when SYCL_PI_LEVEL_ZERO_DISABLE_EVENTS_CACHING is set

Signed-off-by: Zhang, Winston <[email protected]>

Author: winstonzhang-intel

unified-runtime/source/adapters/level_zero/context.cpp

@@ -337,6 +337,20 @@ ur_result_t ur_context_handle_t_::finalize() {
       }
       ZePoolCache.clear();
     }
+    for (auto &ZePool : ZePoolCleanupList) {
+      if (NumEventsAvailableInEventPool[ZePool] == 0 &&
+          checkL0LoaderTeardown()) {
+        auto ZeResult = ZE_CALL_NOCHECK(zeEventPoolDestroy, (ZePool));
+        // Gracefully handle the case that L0 was already unloaded.
+        if (ZeResult && (ZeResult != ZE_RESULT_ERROR_UNINITIALIZED &&
+                         ZeResult != ZE_RESULT_ERROR_UNKNOWN))
+          return ze2urResult(ZeResult);
+        if (ZeResult == ZE_RESULT_ERROR_UNKNOWN) {
+          ZeResult = ZE_RESULT_ERROR_UNINITIALIZED;
+        }
+      }
+    }
+    ZePoolCleanupList.clear();
   }
 
   if (checkL0LoaderTeardown()) {
@@ -420,13 +434,9 @@ ur_result_t ur_context_handle_t_::getFreeSlotInExistingOrNewPool(
   if (!ZePoolCache->empty()) {
     if (NumEventsAvailableInEventPool[ZePoolCache->front()] == 0) {
       if (DisableEventsCaching) {
-        // Remove full pool from the cache if events caching is disabled.
+        ZePoolCleanupList.push_back(*ZePoolCache->begin());
         ZePoolCache->erase(ZePoolCache->begin());
       } else {
-        // If event caching is enabled then we don't destroy events so there is
-        // no need to remove pool from the cache and add it back when it has
-        // available slots. Just keep it in the tail of the cache so that all
-        // pools can be destroyed during context destruction.
         ZePoolCache->push_front(nullptr);
       }
     }

unified-runtime/source/adapters/level_zero/context.hpp

@@ -160,6 +160,7 @@ struct ur_context_handle_t_ : ur_object {
   std::vector<std::list<ze_event_pool_handle_t>> ZeEventPoolCache{30};
   std::vector<std::unordered_map<ze_device_handle_t, size_t>>
       ZeEventPoolCacheDeviceMap{30};
+  std::list<ze_event_pool_handle_t> ZePoolCleanupList;
 
   // This map will be used to determine if a pool is full or not
   // by storing number of empty slots available in the pool.