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The second does not do distributed deadlock prevention. But the second one is redefined to prevent a deadlock scenario the first one does not address. Recursively, only one thread is allowed to pass through a lock. If other threads enter the lock, they must wait until the initial thread that passed through completes n number of times.
Thread safe, MT-safe: Use a mutex for every single resource to guarantee the thread to be free of race conditions when those resources are accessed by multiple threads simultaneously. Thread safety guarantees usually also include design steps to prevent or limit the risk of different forms of deadlocks , as well as optimizations to maximize ...
When disabling interrupts is used to prevent priority inversion, there are only two priorities: preemptible, and interrupts disabled. With no third priority, inversion is impossible. Since there's only one piece of lock data (the interrupt-enable bit), misordering locking is impossible, and so deadlocks cannot occur.
The priority ceiling protocol can be used on uniprocessor systems to minimize the worst-case priority-inversion duration, as well as prevent deadlock. Convoying: all other threads have to wait if a thread holding a lock is descheduled due to a time-slice interrupt or page fault. Some concurrency control strategies avoid some or all of these ...
Random boosting is a strategy used by the scheduler in Microsoft Windows to avoid deadlock due to priority inversion. Ready threads holding locks are randomly boosted in priority and allowed to run long enough to exit the critical section. If the thread doesn't get enough time to release the lock, it will get another chance. [1] [2]
Detecting a deadlock that has already occurred is easily possible since the resources that each process has locked and/or currently requested are known to the resource scheduler of the operating system. [13] After a deadlock is detected, it can be corrected by using one of the following methods: [citation needed]
Upgrading a lock from read-mode to write-mode is prone to deadlocks, since whenever two threads holding reader locks both attempt to upgrade to writer locks, a deadlock is created that can only be broken by one of the threads releasing its reader lock. The deadlock can be avoided by allowing only one thread to acquire the lock in "read-mode ...
For this reason, operating-system kernels often use spinlocks. However, spinlocks become wasteful if held for longer durations, as they may prevent other threads from running and require rescheduling. The longer a thread holds a lock, the greater the risk that the thread will be interrupted by the OS scheduler while holding the lock.