All MCQs

Deadlock prevention designs the resource rules so at least one necessary condition cannot hold.
Deadlock avoidance evaluates each request using future maximum needs and safe-state analysis.

The ostrich approach assumes deadlocks are sufficiently rare or recoverable through manual intervention.
General-purpose systems may choose this trade-off for some resource classes.

A safe state has a safe sequence that permits each process to obtain its remaining needs and complete.
An unsafe state is not necessarily deadlocked, but it can lead to deadlock.

With one instance per resource type, a graph cycle means each process in the cycle waits on the next.
No process in that cycle can obtain the needed resource and proceed.

A resource-to-process edge is an assignment edge.
It records current ownership rather than a pending request.

A process-to-resource edge is a request edge showing an outstanding demand.
An assignment edge points in the opposite direction, from a resource instance to a process.

Resource-allocation graphs conventionally represent processes as circles.
Resource types are shown separately, commonly as rectangles containing instances.

Circular wait forms a closed chain of resource dependencies among processes.
Breaking the possibility of such a cycle prevents deadlock.

No preemption means resources are released only voluntarily by the process holding them.
A process may therefore remain blocked while retaining resources needed elsewhere.

Hold and wait allows a process to retain allocated resources while waiting for others.
This retained ownership can participate in a cycle of dependencies.

Mutual exclusion applies when a resource cannot be shared concurrently among requesting processes.
If every resource were freely shareable, resource deadlock would not arise.

Deadlocked processes cannot progress because each depends on resources or events held by another in the set.
External scheduling alone cannot resolve the circular dependency.