Distributed processing object shared resource control apparatus and method

Claim 1

A method of determining a master process for control of a shared resource in a computer system having a plurality of processes operating on at least one processor that has a memory and access to a shared data storage means, the method comprising: testing said shared data storage means for the presence of a shared resource control file for said shared resource; if no file exists, creating a shared resource control file in said shared data storage means, writing master process identification information to said shared resource control file, and writing a timestamp to said control file; if a file exists, requesting exclusive access to said file; if access denied, waiting and retrying until exclusive access to said file is obtained; if access granted, determining the difference between current time and the last time stamp; if said difference is less then a first preset interval, designating the requesting process as a shadow process; if said difference is greater than said first preset interval, discarding said shared resource control file, creating a new shared resource control file and writing master process identification information to said shared resource control file, and writing a timestamp to said control file; if said requesting process is a master process for said shared resource, replacing the timestamp in said shared resource control file with a current timestamp after a preset second interval has passed.

Claim 2

A method of determining a master process for control of a shared resource in a computer system having a plurality of processes operating on at least one processor that has a memory and access to a shared data storage means, the method comprising: testing said shared data storage means for the presence of a shared resource control file for said shared resource; if no file exists, creating a shared resource control file in said shared data storage means, writing master process identification information to said shared resource control file, and writing a timestamp to said control file; if a file exists, requesting exclusive access to said file; if access denied, waiting and retrying until exclusive access to said file is obtained; if access granted, determining the difference between current time and the last time stamp; if said difference is less then a first preset interval, designating the requesting process as a shadow process; if said difference is greater than said first preset interval, discarding said shared resource control file, creating a new shared resource control file and writing master process identification information to said shared resource control file, and writing a timestamp to said control file; if said requesting process is a master process for said shared resource, replacing the timestamp in said shared resource control file with a current timestamp after a preset second interval has passed.

Claim 5

A system for controlling sharing of a plurality of shared resources in a distributed processing system having a plurality of processors connected by a communications means, the system comprising: means for testing said plurality of shared resources for the presence of a shared resource control file for said shared resource; shared resource control means for creating and storing data in said shared resource control file indicating a process as controlling process for each of said plurality of shared resources and data indicating a time of a last update of said shared resource control means by said controlling process; access control means for limiting exclusive access to said shared resource control means to at most one process; shared resource control read means for reading data from said shared resource control means; comparison means for comparing said data indicating the time of the last update and the current time to determine an elapsed interval; release means for releasing said shared resource control file if said elapsed internal is greater than a first value; update means for periodically causing said controlling process to replace said data indicating the time of the last update with the current time.

Claim 6

A system for controlling sharing of a plurality of shared resources in a distributed processing system having a plurality of processors connected by a communications means, the system comprising: means for testing said plurality of shared resources for the presence of a shared resource control file for said shared resource; shared resource control means for creating and storing data in said shared resource control file indicating a process as controlling process for each of said plurality of shared resources and data indicating a time of a last update of said shared resource control means by said controlling process; access control means for limiting exclusive access to said shared resource control means to at most one process; shared resource control read means for reading data from said shared resource control means; comparison means for comparing said data indicating the time of the last update and the current time to determine an elapsed interval; release means for releasing said shared resource control file if said elapsed internal is greater than a first value; update means for periodically causing said controlling process to replace said data indicating the time of the last update with the current time.

Claim 9

A system for determining a master process for control of a shared resource in a computer system having a plurality of processes operating on at least one processor that has a memory and access to a shared data storage means, the system comprising: means for testing said shared data storage means for the presence of a shared resource control file for said shared resource; means for creating a shared resource control file in said shared data storage means if no file exists, and means for writing master process identification information to said shared resource control file, and writing a timestamp to said control file; means for requesting exclusive access to said file if a file exists; means for waiting and retrying until exclusive access to said file is obtained if access denied; means for determining the difference between current time and the last time stamp if access granted; means for designating the requesting process as a shadow process if said difference is less then a first preset interval; means for discarding said shared resource control file, creating a new shared resource control file and writing master process identification information to said shared resource control file, and writing a timestamp to said control file if said difference is greater than said first preset interval; and means for replacing the timestamp in said shared resource control file with a current timestamp after a preset second interval has passed if said requesting process is a master process for said shared resource.

Claim 10

A system for determining a master process for control of a shared resource in a computer system having a plurality of processes operating on at least one processor that has a memory and access to a shared data storage means, the system comprising: means for testing said shared data storage means for the presence of a shared resource control file for said shared resource; means for creating a shared resource control file in said shared data storage means if no file exists, and means for writing master process identification information to said shared resource control file, and writing a timestamp to said control file; means for requesting exclusive access to said file if a file exists; means for waiting and retrying until exclusive access to said file is obtained if access denied; means for determining the difference between current time and the last time stamp if access granted; means for designating the requesting process as a shadow process if said difference is less then a first preset interval; means for discarding said shared resource control file, creating a new shared resource control file and writing master process identification information to said shared resource control file, and writing a timestamp to said control file if said difference is greater than said first preset interval; and means for replacing the timestamp in said shared resource control file with a current timestamp after a preset second interval has passed if said requesting process is a master process for said shared resource.