Computer network system for detecting global deadlock

DETAILED DESCRIPTION It is therefore an object of the present invention to provide a computer network system capable of accurately detecting a global deadlock.
To achieve this object, according to one aspect of the present invention, a computer network system has nodes linked together.
Each node comprises: a "pseudo; closed path" detecting means, for detecting whether or not a path having a contact to another node at both ends is formed within the self node; check request means for requesting that another node located on one end of the pseudo closed path check if a pseudo closed path is present; transfer means for checking if a pseudo closed path has been formed; and reentrant determining means for, in response to a check request received from another node, determining whether or not the received check request is what has been issued by and returned to the receiving node, and for determining that a global deadlock has occurred when the received check request is the one issued by the receiving node.
According to the second embodiment of the present invention, a computer network system has linked multiple computer systems serving as data processing nodes, at least one of the nodes comprising time monitoring means for monitoring a time from a point of making a request to another node to a point of reception of a response from the another node.
A pseudo closed path detecting means detects if a pseudo closed path is formed within the self node when the time monitoring means detects no response from the another node within a predetermined period of time.
Finally, the second embodiment contains a means for recognizing that a global deadlock is occurring when the pseudo closed path detecting means has detected formation of the pseudo closed path.
According to the third embodiment of the present invention, a computer network system has linked multiple computer systems serving as data processing nodes, at least one of the nodes comprising pseudo closed path detecting means for detecting if a pseudo closed path is formed within the node, itself