Deadlock detecting device
AssigneeFujitsu Limited
InventorKazuhiko Fujita
Life of this patent
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Abstract
Start, commit and abort of transactions in a computer system are managed by a task manager. When a certain transaction locks a certain resource, this information is registered in a lock manager. Accordingly, when a transaction requests for gaining a resource, the lock manager can determine that the resource is already locked, if any, by another transaction. In such a case, the transaction should wait for the termination of the other transaction, so that this information is registered in a wait-for-graph table. A deadlock detector determines whether the deadlock is caused according to the registered information in the wait-for-graph table.
Claims15
A deadlock detecting device of a multitasking system, said device detecting deadlock between plurality of tasks executed in the multitasking system, comprising;
- task managing means for managing parallel execution of plurality of the tasks;
- lock managing means for detecting that one task locks a common resource , and for detecting that another task is waiting for the common resource locked by the former task and outputting waiting relation information indicating that the latter task is waiting for the former task;
- a wait management table for storing a plural pieces of waiting relation information;
- registering means for registering said waiting relation information in said wait management table, every time said lock managing means outputs said waiting relation information;
- and
- deadlock detecting means for detecting the deadlock between plurality of the tasks, of plural pieces of waiting relation involving the tasks which are respectively indicated by any one of the waiting relation information stored in the wait management table forms a loop relation, said deadlock detecting means functioning independently and asynchronously from said lock managing means and said task managing means;
- whereby execution of said first task and said second task is not suspended during deadlock detection.
A deadlock detecting device of a multitasking system, said device detecting deadlock between plurality of tasks executed in the multitasking system, comprising:
- a task manager which manages parallel execution of plurality of the tasks;
- a lock manager which makes one task a common resource, and which detects that another task is waiting for the common resource locked by the former task and consequently output waiting relation information indicating that the latter task is waiting for the former task;
- a wait management table for storing the waiting relation information;
- and
- deadlock detector which detects the deadlock between plurality of the tasks if plural pieces of the waiting relation involving the tasks which are respectively indicated by any one of the waiting relation information stored in the wait management table forms a loop relation, said deadlock detector functioning independently and asynchronously from said lock manager and said task manager;
- whereby execution of said first task and said second task is not suspended during the deadlock detection.
A deadlock detecting device of a distribution system having a plurality of systems, said device detecting deadlock between plurality of tasks each of which is executed in one of the systems and is usable common resources, each system comprising:
- a task manager which manages parallel execution of plurality of the task executed in own system;
- a lock manager which makes one task lock a common resource and which detects that another task is waiting for the common resource locked by the former task and consequently output waiting relation information indicating that the latter task is waiting for the former task;
- means for sending only waiting relation information indicating that one task is waiting for any task executed in other system to this other system, said sending means further sending waiting relation information indicating that one task is waiting for another task involved in the sent waiting relation information;
- a wait management table for storing the waiting relation information outputted by the lock manager of own system and the waiting relation information sent from the sending means of other system;
- a deadlock detector which detects the deadlock between plurality of the tasks, if plural pieces of the waiting relation involving the tasks which are respectively indicated by any waiting relation information stored in the wait management table forms a loop relation, said deadlock detector functioning independently and asynchronously from said lock manager and said task manager;
- whereby execution of said first task and said second task is not suspended during the deadlock detection.
Dependencies are inferred from the claim text.