Data processing: measuring – calibrating – or testing – Measurement system – Performance or efficiency evaluation
Reexamination Certificate
2001-04-05
2003-10-28
Barlow, John (Department: 2863)
Data processing: measuring, calibrating, or testing
Measurement system
Performance or efficiency evaluation
Reexamination Certificate
active
06640203
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to monitoring processes in a computer system. More particularly, the invention relates to a method for monitoring a computer process, to a monitor for monitoring a computer process, to a configuration management system for a computer system and to a computer system incorporating a computer system process and/or a managed process.
The invention find particular, but not exclusive, application to the monitoring of a process called a configuration management system (CMS) daemon (CMSD). A daemon provides a background service in a computer system.
A CMSD manages various system entities, or objects, which could be physical devices or could be software entities. In a particular example, a CMSD is connected via a UNIX socket via an application program interface (API) to application programs (UNIX is a registered trademark in the United States and other countries, exclusively licensed through X/Open Company, Ltd.). The behavior of the CMSD is specified using CMS definitions (CMSDEFs). A CMSDEF includes declarations for objects managed by the CMSD, state evaluations (statements for evaluating the states of objects), and transition code which is executed when a transition occurs between the states of an object.
The CMSDEFs can be thought of as being similar to a set of state machines for the objects to be managed, and the CMSD executes the state machines.
As mentioned, an example of a CMS operates as a daemon (i.e., it supplies a management service in the background). If the CMSD service becomes unavailable, then at least aspects of the operation of the computer system may be compromised. For example, in a particular example of a CMSD for use in a fault tolerant computer system, if the CMSD service becomes unavailable, then the fault tolerance can be compromised. Accordingly, it is necessary to monitor the CMSD to ensure that should it die during operation some corrective action will be taken.
In a prior example of a CMSD for a fault tolerant computer system operable under the UNIX operating system, a simple monitor was provided. This monitor was configured to search for the name of the CMSD process in a UNIX process table. If the process table no longer contained any process of that name, the monitor generated an error message. Of course, a process masquerading as CMSD, or a child of CMSD, or even a non-functioning CMSD that had not been flushed from the process table, would satisfy this monitor. Additionally, with the prior example of a CMSD monitor, the only facility offered was to indicate when the CMSD died, without any recovery being effected. As a result it was necessary for the operator to restart the CMSD manually.
An approach to process monitoring could be based on a system which implements a parent-child approach to process creation, for example in the manner of a UNIX style operating system. With such an approach, a monitored process would be created by a process monitor in the form of a further process that always acts as the parent of the monitored process. This would give the monitor process direct access to information about the monitored process and would usually include it being informed about the death of the monitored process by the operating system. However, the reliance on a direct parent-child relationship puts constraints on the overall system. Also, the monitored process might fail in ways that would not be communicated to its parent by the operating system.
Accordingly, an aim of the invention is to provide for process monitoring with a higher degree of reliability than is available with prior approaches, while still providing for flexible operation and, where possible, automatic restarting of a monitored process that has failed.
SUMMARY OF THE INVENTION
Particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. Combinations of features from the dependent claims may be combined with features of the independent claims as appropriate and not merely as explicitly set out in the claims.
In accordance with one aspect of the invention, there is provided a method of monitoring by a process monitor of a process in a computer system, where the monitored process is not a child of the process monitor. The process monitor uniquely determines the identity of a monitored process and verifies the correct operation of the monitored process. In the absence of verification of the correct operation of the monitored process, the monitored process is caused to initiate (to restart). On successful restarting of the monitored process, the monitored process is uniquely identified to the system.
In accordance with another aspect of the invention, there is provided a method of initiating a process to be monitored in a computer system. The method of initiating a process to be monitored comprises the spawning of a new process by, for example, an upgrade version of an existing process, and then the new process checking that it is operable. In response to a positive result to the tests, the monitored process uniquely identifies itself to the computer system and causes the existing monitored process to terminate, whereby the new process becomes the monitored process.
In accordance with a further aspect of the invention, there is provided a computer system comprising a process to be monitored, the process to be monitored being configured, on successful initiation (starting), uniquely to identify itself to the system, and a process monitor configured: uniquely to determine to identity of a monitored process; to verify correct operation of the monitored process; and, in the event of being unable to verify correct operation of a monitored process, to cause the monitored process to initiate (to restart).
It should be noted that where reference is made to initiating a process, this can relate to starting a new process or an upgrade version of a process, or restarting an existing process, as appropriate. The monitoring of processes in the manner of an embodiment of the invention means that there is no need to rely on a parent child relationship. This enables ‘abdication’ by one process to an upgrade version of that process while still providing continuity and reliable monitoring.
In accordance with yet another aspect of the invention, there is provided a process monitor for such a computer system, the process monitor being configured uniquely to determine to identity of a monitored process, to verify correct operation of the monitored process, and, in the event of being unable to verify correct operation of a monitored process, to cause the monitored process to initiate (to restart).
In accordance with yet a further aspect of the invention, there is provided a process to be monitored, for example in the form of a configuration management system for such a computer system, which is configured, on being initiated (started) by a process monitor, to check that it is operable; and, if so, to provide an indication of this to the process monitor prior to detaching itself from the process monitor.
An embodiment of the invention thereby seeks to provide a solution to the limitations of the prior approaches by providing a process monitor that can monitor the health (or successful operation) of one or more monitored processes that are not children of the process monitor. The process monitor seeks uniquely to identify a monitored process. If successful, it then carries out checks on the process to ensure that the process is still operating. In the event that the process has died, the process monitor then restarts the monitored process. Checks are performed on the monitored process (for example the monitored process may perform self-tests) to ensure it can proceed, before indicating to the monitor process that it has successfully started. An embodiment of the invention enables monitoring of processes without relying on a parent-child relationship and permits new or upgrade versions of processes to be started and for control to be passed reliably from an old process to a new or upgrade process.
The step of d
Applebaum Simon G.
Brown Roger S.
Flanders Joanna Susan
Roles Karen C.
Barlow John
Dougherty Anthony
Flanders Joanna Susan
Kivlin B. Noäl
Meyertons Hood Kivlin Kowert & Goetzel P.C.
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