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Arcflow of interpreted and jitted methods Disclosure Number: IPCOM000013776D
Original Publication Date: 2000-Mar-01
Included in the Prior Art Database: 2003-Jun-18

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When analyzing the performance of a java virtual machine, it is nice to have a way to identify where time is spent performing what type of operations and on behalf of what types of processing. In particular, it is helpful to know what time is spent interpreting method(s) and what time is spent executing the jitted method(s). This knowledge may be used to help determine when to jit a method and in determining how much time to spend jitting a method is warranted. Also, summary statistics, such as, the total time spent interpreting and executing jitted methods for a specific run would be helpful in this determination. Please note that it is not sufficient to simply take the difference between the end time and the start time to identify the time spent executing an interpreted method or a jitted method. This is because other operations could take place, such as, process switches, timer interrupts, key board interrupts, etc. Also, other events could occur during the execution of a method. For example, it is possible that other operations or threads are executing code concurrently. The key to avoiding this problem is in the processing or analysis phase, which could be either real time or post processing. We define a methodology for attributing time spent in a method or process/thread (pid/tid) by identifying the current method or process/thread (pid/tid) as a node and applying base time to the node currently executing whenever a new event occurs. Nodes are either a pid/tid node or a child of a pid/tid node. New child nodes are defined to represent executing the method interpretively as opposed to executing the method once it is jitted. This allows the distinguishing between the execution of the methods interpretively and the execution of the method once it is jitted. This is especially helpful in a mixed mode environment, where methods may be executed for some time interpretively as opposed to being jitted before being executed. Even in a non-mixed mode environment, some of the initialization methods are only executed interpretively as opposed to being jitted before being executed.