- Attacking the Hold and Wait Condition; Can a process hold a resource and ask for another? Can we require processes to request all resources at once? Most processes do not statically know about the resources they need.
- To ensure that the hold-and-wait condition never occurs in the system, we must guarantee that, whenever a process requests a resource, it does not hold any other resources.
- One protocol that can be used requires each process to request and be allocated all its resources before it begins execution.
- An alternative protocol allows a process to request resources only when it has none. A process may request some resources and use them. Before it can request any additional resources, however, it must release all the resources that it is currently allocated.
- To illustrate the difference between these two protocols, we consider a process that copies data from a DVD drive to a file on disk, sorts the file, and then prints the results to a printer.
- Both these protocols have two main disadvantages.
- First, resource utilization may be low, since resources may be allocated but unused for a long period.
- Second, starvation is possible. A process that needs several popular resources may have to wait indefinitely, because at least one of the resources that it needs is always allocated to some other process.
Cem Ozdogan
2010-04-19
