This section describes the types, names, and meanings of Netty memory metrics collected by APM.

**Table 1** Netty memory metrics
Category	Metric	Name	Description	Unit	Data Type	Default Aggregation Mode
Memory (memory: memory metrics)	directMemoryUsage	directMemoryUsage	Used direct memory	-	INT	AVG
Memory (memory: memory metrics)	maxDirectMemory	maxDirectMemory	Maximum direct memory	-	INT	MAX
Exception (exception)	causeType	causeType	Class	-	ENUM	LAST
	exceptionType	exceptionType	Exception type	-	ENUM	LAST
	count	count	Count	-	INT	SUM
	message	message	Exception message	-	STRING	LAST
	stackTrace	stackTrace	Exception stack	-	CLOB	LAST

Netty Memory