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Deadlock avoidance requires that the operating system be given in advance additional information concerning which resources a process will request and use during its lifetime. Deadlock avoidance algorithm analyzes each and every request by examining that there is no possibility of deadlock occurrence in the future if the requested resource is ...
Deadlock commonly refers to: Deadlock (locksmithing) or deadbolt, a physical door locking mechanism; Deadlock (computer science), a situation where two processes are each waiting for the other to finish; Political deadlock or gridlock, a situation of difficulty passing laws that satisfy the needs of the people
This is known as a deadlock (E. W. Dijkstra originally called it a deadly embrace). [1] A simple example is when Process 1 has obtained an exclusive lock on Resource A, and Process 2 has obtained an exclusive lock on Resource B. If Process 1 then tries to lock Resource B, it will have to wait for Process 2 to release it.
Distributed deadlocks can be detected either by constructing a global wait-for graph, from local wait-for graphs at a deadlock detector or by a distributed algorithm like edge chasing. Phantom deadlocks are deadlocks that are detected in a distributed system due to system internal delays but no longer actually exist at the time of detection.
Careless use of locks can result in deadlock or livelock. A number of strategies can be used to avoid or recover from deadlocks or livelocks, both at design-time and at run-time. (The most common strategy is to standardize the lock acquisition sequences so that combinations of inter-dependent locks are always acquired in a specifically defined ...
[2] In OCPP, a task X's priority is raised when a higher-priority task Y tries to acquire a resource that X has locked. The task's priority is then raised to the highest priority had been blocked by itself, ensuring that task X quickly finishes its critical section, unlocking the resource.
Linux also supports mandatory locking through the special -o mand parameter for file system mounting , but this is rarely used. Some Unix-like operating systems prevent attempts to open the executable file of a running program for writing; this is a third form of locking, separate from those provided by fcntl and flock.
The transactional memory could be configured in two modes; the first is an unordered and single-version mode, where a write from one transaction causes a conflict with any transactions reading the same memory address. The second mode is for speculative multithreading, providing an ordered, multi-versioned transactional memory.