I was using the YourKit Java profiler to investigate some performance issues in our code when doing a series of Hibernate generate -generated read queries form our code (most of the resulting SQL queries are 8-16kb of SQL, and typically return only one or two rows , but dozens and dozens of colums columns ). Under this load, of all the CPU time being spent used up by Hibernate, roughly 20% of it (!) was coming from a single stack trace:
{code}
sun.reflect.Reflection.getCallerClass() called from
Class.java: line1783
java.lang.Class.getMethod(String, Class[]) called from
ResultSetWrapperProxy.java: line 137 org.hibernate.engine.jdbc.ResultSetWrapperProxy.locateCorrespondingColumnIndexMethod(Method) called from
ResultSetWrapperProxy.java: line 71
org.hibernate.engine.jdbc.ResultSetWrapperProxy.invoke(Object, Method, Object[])
{code}
The line of code in ResultSetWrapperProxy.java: line 137 of org.hibernate.engine.jdbc.ResultSetWrapperProxy.locateCorrespondingColumnIndexMethod(Method) is:
{code}
return columnNameMethod.getDeclaringClass().getMethod( columnNameMethod.getName(), actualParameterTypes );
{code}
The basic issue here is that ResultSetWrapperProxy.locateCorrespondingColumnIndexMethod(Method) is called often, it's using Java reflection which is slow, and it's not caching the results despite the fact it often repeats. |
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