Operating system--concurrent process deadlock

Tag: The ISS target resource executes the ENTER condition HTTP causes the process

Deadlock Concept:

Refers to two or more than two processes in the course of execution, because of competing resources or due to the communication between each other caused by a blocking phenomenon, if there is no external force, they will not be able to proceed. At this point the system is in a deadlock state or the system generates a deadlock, and these processes, which are always waiting on each other, are called deadlock processes.

deadlock-generated conditions:

(The fourth condition is the most critical)

ways to resolve deadlocks:  

Deadlock Prevention : A Process request resource must follow certain pre-defined constraints to destroy one or more of the four necessary conditions that produce a deadlock to prevent deadlocks from occurring.

Avoid deadlocks : When a process requests a resource, it needs to be judged first (predicted), and if the resource request satisfies the deadlock, the resource request for the deadlock will be rejected, causing the process of the request resource process to block waiting until its required resource is allocated bits.

Learn about learning banker algorithms (http://blog.csdn.net/dk_zhe/article/details/7239376)

The question of the Philosopher's Meal (http://book.51cto.com/art/200907/138168.htm)

Detect and Unlock deadlocks : When a process requests a resource, there is no restriction, which allows a deadlock to occur. However, the system is required to periodically or irregularly detect whether a deadlock occurs. When a deadlock is detected, the deadlock is being sought to be unlocked.

Operating system--concurrent process deadlock