Distributed shared memory

A computer program product for recovering ownership of a plurality of data segments in a distributed shared memory (DSM) having a plurality of distributed shared memory (DSM) agents in a computing storage system using a processor device, the computer program product comprising a non-transitory computer-readable storage medium having computer-readable program code portions stored therein, the computer-readable program code portions comprising:

• upon initiating a request for access to a requested data segment remotely connected and determining by a local DSM agent that the local DSM agent is not the owner of the requested data segment, an upgrade in an access permission to the requested data segment is required, and the local DSM agent has no ongoing messaging session with a remote DSM agent for the requested data segment
• a first executable portion for initiating the messaging session by the local DSM agent by sending a message to a remote DSM agent that the local DSM agent is not the owner of the requested data segment;
• and
• a second executable portion for sending a response by the remote DSM agent to the local DSM agent granting ownership of the requested data segment to the local DSM agent after the remote DSM agent receives the message and determines from local parameters of the remote DSM agent that the remote DSM agent is not the owner of the requested data segment, wherein a predetermined remote DSM agent resolves a no-ownership deadlock by unblocking request for a data segment.

A system for recovering ownership of a plurality of data segments in a distributed shared memory (DSM) having a plurality of distributed shared memory (DSM) agents comprising:

• a plurality of cluster nodes remotely connected to form a computer cluster for the DSM to reside therein, wherein each of the plurality of cluster nodes has a processor, a memory coupled to the processor, local applications in communication with the processor and memory, and one of the plurality of DSM agents, and
• the plurality of DSM agents in communication with the processor and the local applications maintains a local set of memory data segments and associated local parameters which include an access permission and the ownership for one of the plurality of segments by the one of the plurality of DSM agents, wherein the processor and the memory are configured to perform one of:
• upon initiating a request for access to a requested data segment remotely connected and determining by a local DSM agent that the local DSM agent is not the owner of the requested data segment, an upgrade in a permission for access to the requested data segment is required, and the local DSM agent has no ongoing messaging session with a remote DSM agent for the requested data segment:
• initiating the messaging session by the local DSM agent by sending a message to a remote DSM agent that the local DSM agent is not the owner of the requested data segment;
• and
• sending a response by the remote DSM agent to the local DSM agent granting ownership of the requested data segment to the local DSM agent after the remote DSM agent receives the message and determines from local parameters of the remote DSM agent that the remote DSM agent is not the owner of the requested data segment, wherein a predetermined remote DSM agent resolves a no-ownership deadlock by unblocking a request for a data segment.