Abstract:
A system and method of detecting redundant subroutine calls in a software system is provided. Call path data is obtained for the software system and stored into a call tree comprising a plurality of nodes, each node representing a software routine of the software system, the call tree describing the calling paths between the plurality of software routines. At least one focal node is identified among the plurality of nodes in the call tree for redundancy analysis. The calling redundancy to the focal node is analyzed by determining a common ancestor node list for the focal node and by generating call path data for each of the common ancestor nodes on the list. The common ancestor list data may be sorted and call trees generated for the common ancestors in relation to the focal node. This data may then be displayed on a graphical user interface for redundancy analysis of the focal node.

Description:
BACKGROUND  
       [0001]     1. Technical Field  
         [0002]     The technology described in this patent application is generally directed to the field of software performance analysis and diagnostics. More specifically, the technology provides a system and method for detecting redundant subroutine calls in software applications.  
         [0003]     2. Description of the Related Art  
         [0004]     Complex software applications typically comprise hundreds or even thousands of subroutines or functions, each of the subroutines typically performing a particular function or set of functions. The subroutines of the software application communicate with one another by calling one another in a variety of distinct calling paths. A call path is a communication path between two or more subroutines. Oftentimes, the calling paths in complex applications can become redundant as between two subroutines, meaning that there are several communication paths between the subroutines.  
         [0005]     In order to visualize theses calling paths, a call tree is often developed. The call tree is a tree representation of all the software subroutines that are called while a program is executing. Within the call tree, each subroutine is represented by a node, and links between the nodes represent call paths. Several commercially available software performance analysis and diagnostic tools are available that can generate such a calling tree, such as Rational Quantify™ and Intel Vtune™, for example. This call tree data can be expressed as: (i) routine x was called; (ii) routines a and b called x; (iii) routine x calls routines c, d, and e; and (iv) repeat the above sequence (i)-(iii) for each routine in the call path.  
         [0006]     By using this call tree data, a complete call path for every routine of the program under analysis can be generated. The number of times that a routine is called, and how often it is called within a particular call path may also be generated along with the call tree data. By analyzing the data in the call tree, a performance analyst may be able to identify a performance bottleneck.  
         [0007]      FIG. 1  is an example call path diagram  10  showing the execution path between four functional software routines or nodes of an exemplary computer program. In this diagram, the four nodes—afoo  12 , bfoo  14 , cfoo  16 , and foo  18 —communicate with one another through a particular set of execution paths. In this example, the software routine afoo  12  makes a direct call to bfoo  14 , cfoo  16  and foo  18 . In addition, the routine bfoo  14  makes a direct call to foo  18  and cfoo  16 , which in turn makes another direct call to foo  18 . Thus, the routine afoo  12  makes four calls to the routine foo  18 , one direct call, and three indirect calls through the functions bfoo  14  and cfoo  16 . This relationship between afoo and foo is generally termed redundant because of the plurality of calling paths between the two functions.  
         [0008]     Upon determining the redundant relationship between afoo  12  and foo  18 , a performance analyst may determine that a majority of the execution time was spent in foo  18 , and then a software developer may attempt to rewrite the foo  18  routine to make it faster. Alternatively, the software developer may change afoo  12  to call foo  18  only once, and then cache the data returned therefrom and pass it along to bfoo  14  and cfoo  16  so as to eliminate the need for these routines to make another call to foo  18 , thereby eliminating any redundancy.  
         [0009]     Although this may seem like a straightforward approach to fixing the performance problem, in reality these redundant situations are very difficult to detect and diagnose using the commercially available performance analysis tools. Because a typical software application may have hundreds or more of inter-related routines, the resulting calling path data and call trees may become extremely difficult to analyze. Moreover, in determining how a particular function is performing, it is necessary to understand and analyze the calling path of any parent functions. The commercially available tools do not provide sufficient intelligence or functionality to enable this type of problem to be diagnosed by the performance analyst or the software developer.  
       SUMMARY  
       [0010]     A system and method of detecting redundant subroutine calls in a software system is provided. Call path data is obtained for the software system and stored into a call tree comprising a plurality of nodes, each node representing a software routine of the software system, the call tree describing the calling paths between the plurality of software routines. At least one focal node is identified among the plurality of nodes in the call tree for redundancy analysis. The calling redundancy to the focal node is analyzed by determining a common ancestor node list for the focal node and by generating call path data for each of the common ancestor nodes on the list. The common ancestor list data may be sorted and call trees generated for the common ancestors in relation to the focal node. This data may then be displayed on a graphical user interface for redundancy analysis of the focal node. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is an example call path diagram showing the execution path between four functional software routines or nodes;  
         [0012]      FIG. 2  is an example node traversal diagram showing a call tree and a method for traversing the nodes of the call tree;  
         [0013]      FIG. 3  is an example flow chart describing the method for traversing the nodes of the call tree shown in  FIG. 2 ;  
         [0014]      FIG. 4  is a block diagram of an example system for detecting redundant subroutine calls;  
         [0015]      FIG. 5  is a flow chart describing an example method for detecting redundant subroutine calls;  
         [0016]      FIG. 6  is an expanded flow chart describing step  130  of  FIG. 5 ;  
         [0017]      FIG. 7  is an expanded flow chart describing step  132  of  FIG. 5 ;  
         [0018]      FIG. 8A  is a graphical depiction of an example screen display showing a list of common ancestors for a selected focal node in a call tree;  
         [0019]      FIG. 8B  is a graphical depiction of an example screen display showing a common ancestor call tree for a selected common ancestor of the focal node from  FIG. 8A ;  
         [0020]      FIG. 9A  is another example call tree; and  
         [0021]      FIG. 9B  is an example of a common ancestor call tree.  
     
    
     DETAILED DESCRIPTION  
       [0022]     Turning now to the remaining drawing figures,  FIG. 2  is an example node traversal diagram  30  showing a call tree and a method for traversing the nodes of the call tree. In this example, there are eight nodes in the call tree, labeled A through G. The node A is termed the “focal node” in this diagram because it is the node currently under analysis for any redundancy. The “parent tree” of focal node A is shown in  FIG. 2 , which graphically depicts the full call paths of the nodes calling into the focal node. A “parent node” is a node in the call tree that calls a particular node under consideration, and a “child node” is a node that is called by a particular node under consideration. Other familial relationships apply to the description of the call tree as well. For example, nodes G, C and B are the parent nodes to the focal node A and thus the focal node A is the child node to nodes G, C and B. Node F is a parent node to nodes G and C, and thus it is a grandparent node to node A.  
         [0023]     A methodology of traversing the calling paths in a call tree is termed a “node traversal function.” The node traversal function provides a mechanism for tracing all of the possible paths from the focal node to the remaining nodes in the call tree to thereby determine which functions are calling the focal node, and through what paths that function is being called. An example of such steps is shown in table  32  of  FIG. 2 , which lists an exemplary series of steps for tracing the call paths from the focal node A to the other nodes in the call tree.  
         [0024]      FIG. 3  is an example flow chart describing a method  40  for traversing the nodes of the call tree shown in  FIG. 2 . The method begins at  42 . The method is initialized at step  44 , in which a level variable of the focal node is set to a level of 1. The level variable for each node is used as a measure of the distance between any two nodes. The focal node is assigned a level of 1. Parent nodes to the focal node, therefore, have a level of 2. The parent nodes to the parent nodes of the focal node have a level of 3, and so forth. Step  46  checks to determine if there are any unchecked level  2  parent nodes to the focal node. Initially, there must be at least one such node to check. If there are no unchecked level  2  parent nodes, then the method ends at  48 . If there are remaining level  2  parent nodes to be checked (i.e., call paths to the focal node to be traversed), however, then control passes to step  50 .  
         [0025]     At step  50  the method proceeds up the call tree to the next unchecked level  2  parent node, at which point that node is considered checked. From this level  2  node, the method proceeds to conduct one or more checks of any level  3  parent nodes in step  52  that are related to the current level  2  node. If, in step  52 , there are no additional level  3  parent nodes to check with respect to the current level  2  node, then control passes back to step  46  to proceed on to the next level  2  parent node, if one exists. If, however, there are remaining level  3  parent nodes to check with respect to the current level  2  node, then control passes to step  54  in which the current level  3  parent node is flagged as checked. This process of checking each node at each level for additional parent nodes at higher levels continues through steps  56 ,  58 ,  60  and  62  until all N levels of the call tree are traversed and thereby checked for related nodes at different levels of the tree structure.  
         [0026]     Table  32  of  FIG. 2  shows a typical node traversal path using the methodology described in  FIG. 3 . The process begins at the focal node A. From here, the method traces a path up to node G, which is a level  2  parent of node A. From node G, the method then continues the path up to node F, which is a level  3  parent of node A. Node F has no level  4  parents, and thus the method returns back to node G. This node has no additional parents, other than node F, and therefore the method returns back to node A. From here, the method then traces another path from node A up to node C, which is the second level  2  parent of node A. From node C the method then proceeds to node F, a level  3  parent of node A, and then returns to node C because node F has no parent nodes. Similarly, the method then proceeds to node E from node C, and then back to node C and then back to node A. The remaining paths from node A up through the four sub-paths defined by (1) nodes B, C, and F; (2) nodes B, C and E; (3) nodes B, D, and E; and (4) nodes B and D follow a similar logical flow.  
         [0027]      FIG. 4  is a block diagram of an example system  100  for detecting redundant subroutine calls. The system  100  may include a redundant path analyzer component  106 , a display  108 , a performance tool  104 , and a data store  110 . Although shown separately, the redundant path analyzer  106  may, alternatively, be integrated with the performance tool  104 . The system for detecting redundant subroutine calls operates on a software system under test  102 , which is the software application being evaluated for redundant subroutine calls.  
         [0028]     In this example system  100 , the performance tool  104  is utilized to analyze the calling path data of the software system  102  under test, and to generate a call tree  112  thereof. The call tree  112  is preferably stored in the data store  110  for subsequent access and analysis. The redundant path analyzer  106  is a software component that receives the call tree data  112  generated by the performance tool, and generates a redundant path file  114  therefrom. The redundant path file  114  includes, for each focal node analyzed by the redundant path analyzer  106 , a common ancestor list and a common ancestor call tree.  
         [0029]     A common ancestor to the focal node is a routine that calls the focal node through at least two different call paths. For example, as shown in  FIG. 2 , the node E is a common ancestor to the focal node A because it calls A indirectly through three separate call paths, E-C-A; E-C-B-A; and E-D-B-A.  
         [0030]     In addition to storing the redundant path file data  114  in the data store  110 , the redundant path analyzer  106  may also provide the common ancestor list and the common ancestor call tree data to the display  108  in the form of a tabular and/or graphical depiction. In this manner, a performance analyst or software programmer can visualize the common ancestor nodes of the focal node being analyzed, and can also visualize the call tree depicting the calling paths from those common ancestor nodes to the focal node. Using this visual cue, the analyst or programmer can more easily determine performance bottlenecks in the software system  102  under test and may then be able to enhance the performance of the program  102 .  
         [0031]      FIG. 5  is a flow chart describing an example method  120  of detecting redundant subroutine calls using, for example, the system of  FIG. 4 . The method begins at  122 . From here, a call tree is developed in step  124  detailing the calling path relationships between a plurality of the functional nodes in the software system under test  102 . The call tree is developed using, for example, the methodology described in  FIGS. 2-3 , above. This call tree data may be stored in a data store  110  for later use by the method. The call tree may be generated by a performance tool  104 , or it may be generated by the redundant path analyzer  106 .  
         [0032]     In step  126 , the method identifies a particular subroutine as the focal point or focal node of interest. This focal node is identified for further analysis in steps  128  through  136 . The focal node may be identified in a number of ways. First, a performance analyst operating the redundant path analyzer program  106  may select the focal node of interest for analysis. Alternatively, the focal node may be selected automatically by the computer as part of a system analysis of each node in the system, or as part of an analysis of some subset of all the functional nodes in the system that the computer has identified as being called in a potentially redundant manner. In this later implementation, the redundant path analyzer  106  may examine the nodes of the software system  102  that are being called from multiple other nodes and then automatically subject each of these nodes to the methodology set forth in  FIG. 5 .  
         [0033]     Following identification of the focal node, the method then initializes the level variable and count variable for each node in the call tree in step  128 . The level variable has been described previously as a measure of the nodal distance from the focal node to the node under analysis. In step  128 , the level variable is further defined as the lowest level from the focal node to where a particular node of interest under review is found in the calling paths. Thus, if a particular node under analysis is a parent node of the focal node via a first call path, but it is also a grandparent node, then it would be assigned the lower level value of 2 associated with the parent node. The count variable is assigned a value corresponding to the number of times that a subroutine (node) was identified in a calling path. The default value of the count variable is preferably zero.  
         [0034]     Following initialization of the node variables, in step  130  the method then proceeds to determine, for each parent node of the focal node, the number of times that the focal node occurs in the calling path under analysis and the minimum number of levels each parent node is away from the focal node. This step  130  is further described below in reference to  FIG. 6 . Having analyzed all of the parent nodes in each call path to the focal node in step  130 , the method then proceeds to generate a list of common ancestors in step  132 . This step  132  is further described below with reference to  FIG. 7 . This common list of ancestors is then sorted in step  134 , first by the lowest level variable, and then by the highest count variable. Finally, in step  136 , the method generates a full call tree for each of the common ancestors identified in step  132 . The common ancestor list and the common ancestor call tree data may then be stored to the data store  110 , and the analysis depicted in  FIG. 5  may repeat for additional focal nodes of interest in the software system  102  under review.  
         [0035]      FIG. 6  is an expanded flow chart describing step  130  of  FIG. 5 , in which for each parent node to the focal node, two determinations are made: (1) the number of times that the focal node occurs in the calling path to the parent node; and (2) the minimum number of levels from the focal node to the parent node. Step  130  begins at sub-step  140 . From here, the method progresses to the focal node under analysis and the initial level variable is set to 1. Using the node traversal method, such as shown in  FIGS. 2-3 , each parent node to the focal node is then visited for at least several levels of the call tree, preferably stopping at a top level value of between 5 and 10 levels away from the focal node. Allowing the method to progress more than 5 to 10 levels away from the focal node is usually unnecessary, because it becomes more difficult to fix any redundancies at these level distances from the node of interest. Optionally, the operator of the redundant path analyzer  106  may specify the top level value for a particular analysis.  
         [0036]     Subsequently, step  144  progresses to the next parent node to the focal node. This is now the current node under analysis. If the current node is determined to be a parent of the prior node under analysis in step  146 , then the count variable of the current node is incremented in step  148  and a current level pointer is incremented by one in step  150 , else in step  152  the current level pointer is decremented by one. Control of the method then proceeds to step  154 , in which the current level pointer is compared to the current level variable of the node under analysis. If the current level pointer is less than the current level variable, then in step  156  the current level variable is set to the current level pointer. Otherwise the current level variable remains unchanged in step  158 , and control passes to step  160 , which loops back to step  144  to analyze the next node if the node traversal method is not completed. After step  130  is completed, each node in the call tree will be assigned two variables—a level variable and a count variable. This data is subsequently used in steps  132 - 136  of the method to generate the common ancestor call list and the common ancestor call trees.  
         [0037]      FIG. 7  is an expanded flow chart describing step  132  of  FIG. 5 , the step of generating the list of common ancestors to the focal node. The method begins at  170 . Starting at the focal node, a value termed “current count” is set equal to one. Using the node traversal method discussed previously, steps  174 - 186  are executed by visiting each call path of the call tree from the focal node. In step  174 , the next node of the node traversal method is visited for analysis. If the current node is marked as used in step  176 , then control passes to step  186  which determines whether the node traversing method is complete. If the node traversing method is complete in step  186 , then the step  132  ends at  188 , otherwise control passes back to step  174  to iterate to the next node for analysis.  
         [0038]     If the current node was not marked as used in step  176 , then at step  178  the method determines whether the count variable associated with the current node is greater than the “current count” value initialized in step  172 . If the determination in step  178  is positive, then at step  180  the current node, and its level variable, is saved in the common ancestor list of the focal node being analyzed. After step  180  is complete, and also if the determination of step  178  is negative, then at step  182  the “current count” value is set to the count variable associated with the current node. The current node is marked as used in step  184 , and then the method determines whether the node traversing method is complete in step  186 . If the traversing method is complete, then the step  132  ends at  188 , otherwise the process loops back to step  174  to process the next node in the call path.  
         [0039]      FIG. 8A  is a graphical depiction of an example screen display  200  showing a list of common ancestors for a selected focal node in a call tree. Here, the selected focal node is termed TKEWHParse. The graphical display  200  is configured into four panes, a first pane  204  which details the subroutines making a direct call to the focal node, a second pane  202  which lists the common ancestors of the focal node as determined in step  132  of  FIG. 5 , a third pane  208  detailing the subroutines that are called by the focal node, and a fourth pane  206  detailing the common descendants of the focal node. Within the common ancestor list pane  202 , the subroutines are sorted first by the level variable, with the lowest level being at the top of the list, and then secondarily by the count variable. So, for example, the functions “omssmeac” and “omsmacho” both have a level value of 6, but the count value of “omssmeac” is much greater then “omsmacho,” and therefore it is placed above that function on the common ancestor list. The common ancestor list is sorted in this manner because it is likely that the functions that are easiest to fix (or otherwise make more efficient) are those with the lowest level value and the highest count value. For these functions, the performance analyst (or the programmer), may determine that the redundancy of the multiple calls to the focal node may be minimized by calling the focal node routine once and cacheing the data for the calling nodes.  
         [0040]      FIG. 8B  is a graphical depiction of an example screen display  210  showing a common ancestor call tree for a selected common ancestor of the focal node from  FIG. 8A . As described above in step  136  of  FIG. 5 , for each of the common ancestors identified in step  132 , a full call tree is generated from the common ancestor node to the focal node. This call tree data, along with the common ancestor node list may be saved to the data store  110  for subsequent analysis by the performance analyst or programmer. In  FIG. 8B , one of the common ancestor nodes in  FIG. 8A  has been selected for display. Here, the focal node is still the subroutine TKEWHParse and the selected common ancestor is the subroutine “omswuymz,” which is the second node listed in the common ancestor pane  202  of  FIG. 8A . The graphical depiction of the call tree shown in  FIG. 8B  demonstrates that the common ancestor node “omswuymz” calls the focal node subroutine three times, all of which are indirect calls through other subroutines. Hence, the count value associated with “omswuymz” is three. The level value of this subroutine is 2, which represents the shortest indirect calling path between the two nodes. Here, that path is through the function “search1.” The performance analyst may then print out the graphical depiction of the common ancestor call path shown in  FIG. 8B  and work with the programmer to determine whether or not the redundant calling of TKEWHParse from “omswuymz” can be improved. This process of visualizing, printing, and then analyzing the common ancestor call tree data may then proceed for each of the common ancestor nodes identified in step  132  so as to detect and then improve upon the redundancy of the calling paths between the various subroutines of the software system under analysis.  
         [0041]      FIG. 9A  is another example call tree having functional nodes A-K and R. Here, the functional node K has been selected as the focal node for further analysis of redundant calling paths. Following the methodology of  FIGS. 5-7 , the call tree is traversed a first time in order to determine the level and count variables for each of the calling nodes. In this case, the following data results from this first node traversal:  
                                                       NODE   LEVEL   COUNT                           A   3   2           B   4   1           C   3   1           D   2   1           E   1   1           F   2   5           G   2   1           H   1   4           I   1   1           J   1   2           R   4   2                        
         [0042]     During the second traversing of the call paths in step  132  of  FIG. 5  (as further explained in the description of  FIG. 7 ), the common ancestor list is generated. In this example, this second traversal of the call tree results in the following nodes being identified as the common ancestors of node K: F[5:2]; H[4:1]; J[2:1]; and A[2,3], where node[x:y] is the node listing, x is the count variable, and y is the level variable for each node. Subsequently, in step  134  of  FIG. 5 , the common ancestor call list is sorted first by the lowest level variable and then by the highest count variable within each level, resulting in the following sorted common ancestor list: H[4:1]; J[2:1]; F[5:2]; and A[2:3]. For each of these common ancestors of the focal node K, a common ancestor call tree is then generated, such as shown in  FIG. 9B .  FIG. 9B  is an example of a common ancestor call tree for the common ancestor node H showing the four call paths that exist between this node and the focal node K.  
         [0043]     While certain examples have been used to disclose and illustrate one or more embodiments of the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention, the patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art.  
         [0044]     It is further noted that the systems and methods disclosed herein may be implemented on various types of computer architectures, such as for example on a single general purpose computer or workstation, or on a network (e.g., local area network, wide area network, or internet), or in a client-server configuration, or in an application service provider configuration. Also, the system&#39;s and method&#39;s data (such as hierarchical dimensional data or other forms of data elements) may be stored as one or more data structures in computer memory and/or storage depending upon the application at hand. The systems and methods may be provided on many different types of computer readable media including instructions being executable by a computer to perform the system and method operations described herein. The systems and methods may also have their information transmitted via data signals embodied on carrier signals (e.g., radio frequency carrier signals) or other communication pathways (e.g., fiber optics, infrared, etc.).  
         [0045]     The computer components, software modules, functions and data structures described herein may be connected directly or indirectly to each other in order to allow the flow of data needed for their operations. It is also noted that a module includes but is not limited to a unit of code that performs a software operation, and can be implemented for example as a subroutine unit of code, or as a software function unit of code, or as an object (as in an object-oriented paradigm), or as an applet, or in a computer script language, or as another type of computer code. The computer components may be located on a single computer or distributed across multiple computers depending upon the situation at hand.