Abstract:
The present invention discloses a solution for adding a profiling agent to a virtual machine (VM), which permits unit test programs to access information relating to memory and performance from runtime data areas of the VM. Operations permitted by the agent can include starting/stopping VM monitor, getting objects from the heap, retrieving an invocation count, determining a size of an instantiated object, getting a current thread time, and the like. Memory and performance information gathered during a test can be stored for later analysis under a test version identifier. A comparison engine can create reports that use the stored performance and memory data, which can help developers compare memory/performance deltas among different unit versions. In one embodiment, the VM can be a JAVA VIRTUAL MACHINE (JVM) and the unit test programs can be JUNIT programs.

Description:
BACKGROUND 
     Field of the Invention 
     The present invention relates to the field of unit testing of virtual machine components and, more particularly, to adding a profiling agent to a virtual machine to permit performance and memory consumption analysis within unit tests. 
     Description of the Related Art 
     A number of languages, like JUNIT, exist expressly for conducting unit tests of software units configured to execute within a virtual machine environment, such as a JAVA VIRTUAL MACHINE (JVM). Unit testing can be valuable as it permits one or more software units to be tested throughout a software development cycle by simply executing a unit test program. When a software unit requires iterative testing during its lifecycle, an initial cost of constructing a unit test program can be considerably outweighed with long term savings gained throughout the software development cycle. 
     Black and white box testing of units using unit tests generally don&#39;t include tests for memory usage and/or performance. This is expressed in the JUNIT language by a lack of memory and/or performance related asserts. When unit tests include memory and/or performance checks, results are often less than perfect and writing the testing code can be challenging. Executing unit tests for memory and performance related information is difficult because needed information from a virtual machine is not currently exposed. For example, in the JUNIT API, there is no API access to the heap, there is no access to object size, there is no memory specific asserts, and there is no control over a garbage collector. Additionally, no information is available to access thread specific timers, to query a method invocation count, and no performance related asserts exist. 
     SUMMARY OF THE INVENTION 
     The present invention discloses a solution for adding a profiling agent to a virtual machine, which permits unit test programs to access information relating to memory and performance from runtime data areas of the virtual machine (VM). Operations permitted by the agent can include starting/stopping VM monitor, getting objects from the heap, retrieving an invocation count, determining a size of an instantiated object, getting a current thread time, and the like. Memory and performance information gathered during a test can be stored for later analysis under a test version identifier. A comparison engine can create reports that use the stored performance and memory data, which can help developers compare memory/performance deltas among different unit versions. In one embodiment, the VM can be a JAVA VIRTUAL MACHINE (JVM) and the unit test programs can be JUNIT programs. Further, JUNIT can be extended to include one or more asserts related to memory and/or performance information exposes through the agent. 
     The present invention can be implemented in accordance with numerous aspects consistent with material presented herein. For example, one aspect of the present invention can include a system for performing unit testing that includes a virtual machine, a profiling agent, and a unit testing framework. The virtual machine can be configured to execute software units. The unit testing framework can be configured to test software units executing within the virtual machine. The profiling agent can be an agent of the virtual machine that exposes memory and performance information from runtime data areas of the virtual machine to the unit testing framework, which would not otherwise be exposed. The unit testing framework can execute a set of methods relating to memory and performance of the runtime data areas, where the set of methods interact with the profiling agent. 
     Another aspect of the present invention can include an extension to a unit testing framework that includes a set of published methods available for unit testing purposes relating to memory and/or performance aspects of an application virtual machine. These memory and performance aspects can be gathered from runtime data areas of the application virtual machine by a profiling agent. The published methods can include any or all of the following: a get heap method, a get invocation count method, a get size of object method, a get current thread time method, and a get data model method. 
     Still another aspect of the present invention can include a method for exposing runtime data areas of a virtual machine to a unit testing framework. The method can include a step of placing a profiling agent within an application virtual machine that has access to runtime data areas of the application virtual machine. An interface class can be established for exchanging information with the profiling agent. The interface class can include a set of public methods available to a unit testing framework. The public methods can provide memory and performance related information concerning objects in a heap of the application virtual machine and threads executing within the application virtual machine. 
     It should be noted that various aspects of the invention can be implemented as a program for controlling computing equipment to implement the functions described herein, or a program for enabling computing equipment to perform processes corresponding to the steps disclosed herein. This program may be provided by storing the program in a magnetic disk, an optical disk, a semiconductor memory, any other recording medium, or can also be provided as a digitally encoded signal conveyed via a carrier wave. The described program can be a single program or can be implemented as multiple subprograms, each of which interact within a single computing device or interact in a distributed fashion across a network space. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       There are shown in the drawings, embodiments which are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. 
         FIG. 1  is a schematic diagram illustrating a system that uses a profiling agent to expose memory and performance information of a virtual machine (VM) to a test unit framework in accordance with an embodiment of the inventive arrangements disclosed herein. 
         FIG. 2  is a schematic diagram of an implementation for an agent that exposes virtual machine information to a unit testing framework. 
         FIG. 3  is a flow chart showing a method in which a profiling agent is able to expose memory and performance information concerning a VM to unit test programs in accordance with an embodiment of the inventive arrangements disclosed herein. 
         FIG. 4  is a schematic for a sample model class diagram, such as a model conforming to an ECLIPSE MODEL FRAMEWORK (EMF) data model as described in  FIG. 2 . 
         FIG. 5  shows JUNIT extensions for memory and performance in accordance with an embodiment of the inventive arrangements disclosed herein. 
         FIG. 6  shows a sample differences report able to be generated by comparing differences between different unit tests of a common software object executing in a VM in accordance with an embodiment of the inventive arrangements disclosed herein. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a schematic diagram illustrating a system  100  that uses a profiling agent  112  to expose memory and performance information of a virtual machine (VM)  110  to a test unit framework in accordance with an embodiment of the inventive arrangements disclosed herein. The profiling agent  112  can access information from runtime data areas  120  of the VM  110 , such as a heap  122  and objects  124  contained therein. The agent  112  can either trigger a garbage collector  126  to perform collection actions or can prevent normally occurring actions from executing. Additionally, the agent  112  can access thread information  129  from stacks and/or registers  128  of the VM  100 . All of this information is made available to an agent front end  140 , which can be an interface class in an object oriented implementation of system  100 . 
     The agent front-end  140  can include a plurality of public methods for obtaining information from the runtime data areas  120  and for initiating actions involving the runtime data areas  120 . These methods can include, but are not limited to, start/stop methods  142 , a get heap method  143 , a get invocation count  144  method, a get size of object  145  method, a get current thread time  146  method, a get data model  147  method, and the like. Each of the methods  142 - 147  can be public methods able to be accessed from within xUnit  160  framework. 
     The start/stop  142  methods can start/stop a monitoring of memory and/or performance involving agent  112 . Get heap  143  can force the garbage collector  126  to start and can then give access to all objects  124  in the heap  122 . Get invocation count  144  can return how many times a specific method has been called during a monitoring period. One implementation of get size of object  145  can return a shallow size of an object  124 . This result can depend upon the virtual machine  110  and the operating system. A different implementation of get size of object  145  can return a retained size of a specified object  124 . Get current thread time  146  can return a current thread CPU time. Get data model  147  can return a set of optionally processed run data  132  from the data store  130 . 
     Each time a unit test program is run, the agent  112  can monitor memory and/or performance. This information can be stored within data store  130  as run data  132  along with a run version identifier. A compare engine  152  can be a software engine that compares data collected across different runs  132 . A report engine  154  can generate customizable reports based upon results of the compare engine  152 . In one embodiment, a data model can be established that represents a set of collected data for a run as well as deltas between that run and one or more previous runs for past versions of the tested unit. 
     In addition to being able to execute the exposed methods  142 - 147 , the xUnit  160  framework can be extended to include one or more asserts  162 - 165  that are related to memory and/or performance of the virtual machine  110 . These asserts  162 - 165  can depend upon actions performed by and data provided by the agent  112 . 
     In system  100 , the VM  110  can be a process VM or an application VM, which runs as a normal application inside an operating system and that supports a single process. The VM  110  can provide a platform independent programming environment that abstracts away details of the underlying hardware/OS and that permits programs written for the VM  110  to execute in the same way on any platform. The VM  110  can include a JAVA VIRTUAL MACHINE, a COMMON LANGUAGE RUNTIME from the .NET FRAMEWORK, and the like. 
     The xUnit  160  is a code-driven testing framework, which can include test fixtures, test suites, and test execution. xUnit  160  includes JUNIT as well as other sUnit based language ports, such as PHPUnit, NUnit, PyUnit, fUnit, Test::Class, Test::Unit, CPPUnit, and the like. 
       FIG. 2  is a schematic diagram  200  of an implementation for an agent that exposes virtual machine information to a unit testing framework. Specifically, diagram  200  presents an implementation for JUNIT based testing of software units within a JAVA VIRTUAL MACHINE  232 . Diagram  200  represents one contemplated implementation of system  100 . 
     In diagram  200 , the profiling agent  230  can be written using a C++ programming language, which can include builds for various operating system platforms, such as WIN32, WIN64, LINUX, etc. The agent  230  can be a JVM profiling interface (JVMPI) agent, a JVM tooling interface (JVMTI) agent, and the like. The agent  230  can communicate with the JVM  232 , which exposes some of its internal functionality specific to memory and performance analysis. 
     The JVM Helper  222  can be a JAVA interface for the C++ agent  230  that enables data to be exchanged between the JAVA and the C++ interfaces. API&#39;s for the JVM Helper  222  can include the methods analogous to methods  142 - 147  detailed in system  100 . Helper can use a Java Native Interface (JNI)  234  to communicate with agent  230 . 
     An Eclipse Modeling Framework (EMF)  224  can communicate with JUNIT  220  and the JVM helper  222 . THE EMF  224  can include a data model that represents collected data model and the delta model to support comparing data collected across different runs. The EMF  224  model can include a compare engine, which accepts data roots and products a delta model that represents the differences. 
       FIG. 3  is a flow chart showing a method  300  in which a profiling agent is able to expose memory and performance information concerning a VM to unit test programs in accordance with an embodiment of the inventive arrangements disclosed herein. The method  300  can be performed in the context of a system  100  or  200 . 
     Method  300  can begin in step  305 , where a profiling agent for a VM can be established. In step  310 , memory/performance specific interfaces can be established using an interface front end linked to the profiling agent. The front-end can, for example, be an interface class that exposes memory and performance related methods to a test framework. In step  315 , a unit test program can execute while the agent is monitoring performance/memory aspects of the VM. The unit test program can include one or more method calls to a memory/performance related method, as shown by step  320 . The agent can access a runtime data area of the VM and can convey results to the unit test program and/or perform programmatic actions initiated by the unit test program. In step  325 , results of the unit test can be presented. 
     In step  330 , a determination can be made as to whether a data capture feature for the test run was enabled. If so, the profiling agent can store all captured memory/performance data related to the test, as shown by step  335 . In step  340 , a determination can be made as to whether another run of the test program is to be executed. When so, the method can progress from step  340  to step  315  where the unit test program can again execute. This execution can be for a different or for the same version of unit software. In step  345 , an option can be provided to compare one or more runs, which can include a newly executed run. If no comparison is opted for, the method can end. Otherwise, the method can progress from step  345  to step  350 , where two or more runs can be identified and retrieved from a storage area, such as the storage area where data from step  335  was stored. In step  355 , a run comparison report based upon the retrieved data can be generated and presented to a requester. 
       FIG. 4  is a schematic for a sample model class diagram  400 , such as a model conforming to an ECLIPSE MODEL FRAMEWORK (EMF) data model as described in system  200 . The supported deltas  408  shown in model  400  include an add delta  412 , a delete delta  414 , and a change delta  410 . 
     Model specifics are variable by implementation and diagram  400  is presented to illustrate a concept. The scope of the disclosed invention is not to be limited by specifics shown in diagram  400  in any manner since the disclosed invention is able to utilize any model and not just that detailed in diagram  400 . 
       FIG. 5  shows JUNIT extensions for memory  510  and performance  520  in accordance with an embodiment of the inventive arrangements disclosed herein. 
       FIG. 6  shows a sample differences report  610  able to be generated by comparing differences between different unit tests of a common software object executing in a VM in accordance with an embodiment of the inventive arrangements disclosed herein. In one embodiment, the report  610  can represent an HTML report that has been generated from a delta data model (i.e., one of the EMF data models expressed in diagram  400 ) 
     The present invention may be realized in hardware, software, or a combination of hardware and software. The present invention may be realized in a centralized fashion in one computer system or in a distributed fashion where different elements are spread across several interconnected computer systems. Any kind of computer system or other apparatus adapted for carrying out the methods described herein is suited. A typical combination of hardware and software may be a general purpose computer system with a computer program that, when being loaded and executed, controls the computer system such that it carries out the methods described herein. 
     The present invention also may be embedded in a computer program product, which comprises all the features enabling the implementation of the methods described herein, and which when loaded in a computer system is able to carry out these methods. Computer program in the present context means any expression, in any language, code or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after either or both of the following: a) conversion to another language, code or notation; b) reproduction in a different material form. 
     This invention may be embodied in other forms without departing from the spirit or essential attributes thereof. Accordingly, reference should be made to the following claims, rather than to the foregoing specification, as indicating the scope of the invention.