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Method and Apparatus for Maintaining Permanent UNIX Processes

IP.com Disclosure Number: IPCOM000015155D
Original Publication Date: 2002-May-21
Included in the Prior Art Database: 2003-Jun-20

Publishing Venue



This invention introduces the concept of a permanent UNIX process. A permanent UNIX process is one that survives a shutdown of the UNIX System Services environment. This allows address spaces that use UNIX System Services for part of their functionality to continue to function for other purposes while UNIX System Services is shutdown. The address spaces that could gain advantage from this include CICS, DB2, RMF and NETVIEW, since these system address spaces provide significant functionality that doe not require UNIX System Services. Without this capability, these system address spaces would have to be terminated and subsequently restarted when UNIX System Services is shutdown. On other UNIX platforms a shutdown will force all processes to be terminated, none of the processes on those systems are permitted to survive a shutdown. The concept of a permanent UNIX process did not exist in the prior art. The shutdown of UNIX System Services is initiated by a F OMVS,SHUTDOWN console command. This will cause all non-permanent processses to be terminated via the sending of SIGTERM and SIGKILL signals and results in the cleanup of most UNIX System Services resources. Once all non-permanent processes have ended, the permanent processes will have their key UNIX Systerm Services resources checkpointed, but will not be terminated. When UNIX System Services shutdown is complete permanent processes will be unable to use services provided by the UNIX System Services kernel. All other operating system services would be available to these processes. To be identified as a permanent process, a new shutdown registration function is provided via the BPX1ENV service (SHUTDOWN_REG and via the BPX1SDD service DUBJOBPERM ). The new SHUTDOWN_REG function of BPX1ENV provides the capability for certain privileged address spaces to register either the calling process or job to be permanent. As part of the SHUTDOWN_REG function the caller can optionally request that a SIGDANGER signal or an exit is driven when the shutdown is initiated as an early warning that a shutdown is imminent. Additionally, the caller can request that UNIX System Services kernel services fail with a return code, abend or wait the caller when UNIX System Services is shutdown. The new DUBJOBPERM function of BPX1SDD allows a privileged address space to register the job as being permanent. Once registered as permanent, a process or job would not be terminated and would be permitted to stay active while UNIX System Services is shutdown. The restart of UNIX System Services is initiated by a F OMVS,RESTART console command. This causes the startup of UNIX System Services. Once the UNIX System Services kernel address space is reinitialized, the INIT process is reestablished as part of UNIX System Services initialization and it will initiate the restarting of /etc/init and other UNIX Daemons. When the INIT process is first being reinitialized the reestablishment of the UNIX System Services resources for the checkpointed permanent processes is done so that the permanent processes can begin using UNIX System Services again. 1