Backported fix for CORE-3908: Engine leaks memory and crashes when lo…

…t of autonomous transactions have been started and finished

src/jrd/tra.cpp

@@ -1604,7 +1604,7 @@ jrd_tra* TRA_start(thread_db* tdbb, ULONG flags, SSHORT lock_timeout, Jrd::jrd_t
 	// To handle the problems of relation locks, allocate a temporary
 	// transaction block first, seize relation locks, then go ahead and
 	// make up the real transaction block.
-	MemoryPool* const pool = outer ? outer->tra_pool : dbb->createPool();
+	MemoryPool* const pool = outer ? outer->getAutonomousPool() : dbb->createPool();
 	Jrd::ContextPoolHolder context(tdbb, pool);
 	jrd_tra* const temp = jrd_tra::create(pool, attachment, outer);
 
@@ -1659,7 +1659,7 @@ jrd_tra* TRA_start(thread_db* tdbb, int tpb_length, const UCHAR* tpb, Jrd::jrd_t
 	// To handle the problems of relation locks, allocate a temporary
 	// transaction block first, seize relation locks, then go ahead and
 	// make up the real transaction block.
-	MemoryPool* const pool = outer ? outer->tra_pool : dbb->createPool();
+	MemoryPool* const pool = outer ? outer->getAutonomousPool() : dbb->createPool();
 	Jrd::ContextPoolHolder context(tdbb, pool);
 	jrd_tra* const temp = jrd_tra::create(pool, attachment, outer);
 
@@ -3541,6 +3541,11 @@ jrd_tra::~jrd_tra()
 	}
 
 	DFW_delete_deferred(this, -1);
+
+	if (tra_autonomous_pool)
+	{
+		MemoryPool::deletePool(tra_autonomous_pool);
+	}
 }
 
 
@@ -3554,6 +3559,36 @@ UserManagement* jrd_tra::getUserManagement()
 }
 
 
+MemoryPool* jrd_tra::getAutonomousPool()
+{
+	if (!tra_autonomous_pool)
+	{
+		MemoryPool* pool = tra_pool;
+		jrd_tra* outer = tra_outer;
+		while (outer)
+		{
+			pool = outer->tra_pool;
+			outer = outer->tra_outer;
+		}
+		tra_autonomous_pool = MemoryPool::createPool(pool, tra_memory_stats);
+		tra_autonomous_cnt = 0;
+	}
+
+	return tra_autonomous_pool;
+}
+
+
+void jrd_tra::releaseAutonomousPool(MemoryPool* toRelease)
+{
+	fb_assert(tra_autonomous_pool == toRelease);
+	if (++tra_autonomous_cnt > TRA_AUTONOMOUS_PER_POOL)
+	{
+		MemoryPool::deletePool(tra_autonomous_pool);
+		tra_autonomous_pool = NULL;
+	}
+}
+
+
 /// class TraceSweepEvent
 
 TraceSweepEvent::TraceSweepEvent(thread_db* tdbb) :

src/jrd/tra.h

@@ -129,11 +129,12 @@ class jrd_tra : public pool_alloc<type_tra>
 		tra_blob_space(NULL),
 		tra_undo_space(NULL),
 		tra_undo_record(NULL),
-		tra_user_management(NULL)
+		tra_user_management(NULL),
+		tra_autonomous_pool(NULL),
+		tra_autonomous_cnt(0)
 	{
 		if (outer)
 		{
-			fb_assert(p == outer->tra_pool);
 			tra_arrays = outer->tra_arrays;
 			tra_blobs = outer->tra_blobs;
 		}
@@ -162,7 +163,10 @@ class jrd_tra : public pool_alloc<type_tra>
 		{
 			if (transaction->tra_outer)
 			{
+				jrd_tra* outer = transaction->tra_outer;
+				MemoryPool* const pool = transaction->tra_pool;
 				delete transaction;
+				outer->releaseAutonomousPool(pool);
 			}
 			else
 			{
@@ -223,8 +227,14 @@ class jrd_tra : public pool_alloc<type_tra>
 
 	Record* tra_undo_record;	// temporary record used for the undo purposes
 	UserManagement* tra_user_management;
+	MemoryPool* tra_autonomous_pool;
+	USHORT tra_autonomous_cnt;
+	static const USHORT TRA_AUTONOMOUS_PER_POOL = 64;
 
 public:
+	MemoryPool* getAutonomousPool();
+	void releaseAutonomousPool(MemoryPool* toRelease);
+
 	SSHORT getLockWait() const
 	{
 		return -tra_lock_timeout;