Data processing: software development – installation – and managem – Software program development tool – Testing or debugging
Reexamination Certificate
1999-12-29
2004-06-01
Dam, Tuan (Department: 2122)
Data processing: software development, installation, and managem
Software program development tool
Testing or debugging
C717S129000, C717S130000, C717S133000, C717S158000, C714S039000, C714S047300
Reexamination Certificate
active
06745383
ABSTRACT:
BACKGROUND OF THE INVENTION
With the proliferation of the internet and electronic commerce (“eCommerce”), businesses have begun to rely on the continuous operation of their computer systems. Even small disruptions of computer systems can have disastrous financial consequences as customers opt to go to other web sites or take their business elsewhere.
One reason that computer systems become unavailable is failure in the application or operating system code that runs on them. Failures in programs can occur for many reasons, including but not limited to, illegal operations such as dividing by zero, accessing invalid memory locations, going into an infinite loop, running out of memory, writing into memory that belongs to another user, accessing an invalid device, and so on. These problems are often due to program bugs.
Ayers, Agarwal and Schooler (hereafter “Ayers”), “A Method for Back Tracing Program Execution,” U.S. application Ser. No. 09/246,619, filed on Feb. 8, 1999 and incorporated by reference herein in its entirety, focuses on aiding rapid recovery in the face of a computer crash. When a computer runs an important aspect of a business, it is critical that the system be able to recover from the crash as quickly as possible, and that the cause of the crash be identified and fixed to prevent further crash occurrences, and even more important, to prevent the problem that caused the crash from causing other damage such as data corruption. Ayers discloses a method for recording a sequence of instructions executed during a production run of the program and outputting this sequence upon a crash.
Traceback technology is also important for purposes other then crash recovery, such as performance tuning and debugging, in which case some system event or program event or termination condition can trigger the writing out of an instruction trace.
The preferred method for traceback disclosed by Ayers is binary instrumentation in which code instrumentation is introduced in an executable. The instrumentation code writes out the trace.
Agarwal, “Test Protection, and Repair Through Binary-Code Augmentation,” U.S. Pat. No. 5,966,541, issued on Oct. 12,1999 and incorporated by reference herein in its entirety, discloses a method of binary instrumentation for aiding in testing programs through test coverage. The instrumentation marks instructions which were executed during a test run. Software test engineers or other testers could then write specific tests for the untested code, thereby improving overall test quality. One of the key aspects of the instrumentation technology is that it introduces virtually no overhead since it adds vew few extra instructions into the code directly, and does not involve expensive procedure calls. Improved testing also helps to discover and fix bugs, thereby resulting in higher availability for the system.
SUMMARY OF THE INVENTION
Traceback is a reactive tool. It promotes recovery when the program has crashed. But it does not usually warn of the possibility of a crash
The present invention, on the other hand, inserts binary instrumentation into a program which issues an “early warning” such as an email to an operator when the program enters a block of untested code which has been recently changed. Changed, untested codes are common causes of failures. Early warnings can also be issued upon other events that are likely to cause a failure.
Accordingly, a computer method for issuing an early warning includes determining, using a control flow graph representation of a program, locations in the program at which to insert EW code to monitor for an event. The program is instrumented with EW code which monitors for the event, by inserting EW code at the determined locations. Upon detecting the event, EW code performs an early action warning, or issues an early action.
In at least one embodiment, instrumenting the program is done by first injecting code coverage instrumentation into the program. Then, the code coverage-instrumented program is tested to provide coverage information. Finally, untested blocks are instrumented to perform an early warning action.
Instrumenting the program further comprises determining which program blocks in the program are changed relative to an earlier version of the program. Then, only untested blocks that are changed are instrumented to perform an early warning.
Early warnings in general are issued when an EW-instrumented block is reached. In one embodiment, the event is the reaching of program code which has changed relative to a prior version of the program.
Issuance of an early warning action can be conditional upon execution of the program in a particular environment, such as a production environment.
The issuing of an early warning can include, but is not limited to, sending an email to one or more people such as developers, testers, managers and/or operators, or to another computer system. The email can include information such as a traceback history.
The issuing of an early warning can also include, but is not limited to, writing an early warning log entry into a log file, which can be periodically checked by a human or by a processor. Furthermore, the log file or a portion thereof can be included in the email discussed above.
The issuing of an early warning can also include, but is not limited to, sending a message to a console, where the message causes the change of a human-perceptible characteristic. For example, the characteristic can be the color, visibility, shape, size or blinking state of an icon displayed on the console, or a combination thereof, where the icon is specific to the application. The characteristic can also be the sounding an audible alarm, or alternately, the turning off and on an audible alarm. This, of course, can be combined with the change of the icon's state. The message itself can be sent by various methods, including SNMP protocol traps.
The issuing of an early warning can also include, but is not limited to, placing the program into a wait state, halting the program, sending an alarm to an operator, or triggering a failover.
Furthermore, in some embodiments, EW code can be deactivated for a block after a predetermined number of early warnings have issued for the block. A table can be maintained, for example, to track the number of early warnings issued for each EW-instrumented block.
Alternatively, in some embodiments, EW code can be deactivated for the entire program, for example, after a predetermined number of early warning actions have been performed. This can be accomplished, for example, by checking for a predetermined condition before issuing the early warning, and issuing the early warning only if the predetermined condition is not true. Examples of predetermined conditions include, but are not limited to, a predetermined value stored in a known file or in an environmental variable.
Issuance of an early warning can also occur upon an event such as the execution of a user-inserted assert or warning statement, or before a file is opened, wherein the EW issues if a null pointer about to be passed to a system function. In some embodiments, an EW will issue if the value of an argument to some function exceeds a predetermined range.
In yet another embodiment, the EW code is placed in a loop, and issues an EW if the loop is executed more than a predetermined number of times.
In yet another embodiment, the EW code issues an EW upon the execution of user-marked code.
In another embodiment, the EW code issues an EW when the time duration between execution of two points in the program exceeds a predetermined value. The two points can be, for example, around a system call, a network request call, or a database interaction call.
In yet another embodiment, the EW code issues an EW upon the detection of an untested configuration. This can be implemented, for example, by maintaining a list of test configuration sets which have been tested. A configuration which does not match one of the listed test configuration sets is determined to be an untested configuration. A test configuration set can include, but i
Agarwal Anant
Ayers Andrew E.
Schooler Richard
Dam Tuan
Kivlin B. Noäl
Meyertons Hood Kivlin Kowert & Goetzel P.C.
Veritas Operating Corporation
Vo Ted T.
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