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Reliable datagram service provider for fast messaging in a clustered environment

  • US 5,699,500 A
  • Filed: 06/01/1995
  • Issued: 12/16/1997
  • Est. Priority Date: 06/01/1995
  • Status: Expired due to Term
First Claim
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1. A distributed lock manager (DLM) for a clustered computer system, said clustered computer system including a plurality of processing nodes and having a plurality of application processes operating within said plurality of processing nodes, said distributed lock manager comprising:

  • a plurality of virtual circuits, a virtual circuit between each pair of said processing nodes within said clustered computer system; and

    within each one of said processing nodes;

    a shared memory segment for storing lock status information for said one of said processing nodes, said shared memory segment being shared by said plurality of application processes to access the lock status information stored therein;

    a shared library providing said plurality of application processes access to said shared memory segment to request and be granted a lock if said lock is available;

    a DLM control program providing exception handling for any exception which occurs with respect to a lock managed within said one of said processing nodes; and

    a DLM driver including a communication service providing for the generation of data packets comprising lock manager instructions for transmission to other ones of said processing nodes via said virtual circuits, said communication service also providing for the receipt of data packets generated and transmitted by other ones of said processing nodes, said communication service further including means for testing the integrity of a virtual circuit between a sending processing node and a receiving processing node, said means generating a periodic keepalive message packet which is periodically sent by said sending processing node to said receiving processing node requesting the transmission of an acknowledge signal in response thereto, said keepalive message packet being transmitted in the absence of the receipt of a data packet from said receiving processing node for a predetermined period of time.

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