Deadlock Handling
Conditions and strategies for dealing with deadlocks.
The four necessary conditions for deadlock, the strategies for dealing with it (prevention, avoidance, detection and recovery) and related hazards such as livelock and starvation. Each entry is a one-line definition suitable for exam review or design discussion.
Use it when
- You are diagnosing a hang and need the vocabulary for what is happening.
- You are choosing between preventing deadlock and detecting it.
Watch out for
- Most general-purpose operating systems do not prevent deadlock for user programs; they leave it to application design.
- Banker's algorithm needs advance knowledge of maximum resource needs, which is rarely available.
The data
15 rows
| Concept | Description |
|---|---|
| Mutual Exclusion | At least one resource must be non-sharable. |
| Hold and Wait | A process holds resources while waiting for additional ones. |
| No Preemption | Resources cannot be forcibly taken from a process. |
| Circular Wait | A circular chain of processes each waiting for a resource held by the next. |
| Banker's Algorithm | Deadlock avoidance using safety checks on resource allocation. |
| Deadlock Prevention | Design the system so at least one necessary condition cannot hold. |
| Deadlock Detection | Periodically check the resource allocation graph for cycles. |
| Resource Allocation Graph | A directed graph of processes and resources; a cycle indicates possible deadlock, and certain deadlock when each resource has a single instance. |
| Safe State | A state in which there is an order in which every process can finish even if all request their maximum needs. |
| Deadlock Avoidance | Granting a request only if the resulting state remains safe, as the Banker's algorithm does. |
| Deadlock Recovery | Breaking a detected deadlock by terminating processes or preempting resources. |
| Lock Ordering | Requiring all code to acquire locks in one global order, which removes circular wait. |
| Livelock | Processes keep changing state in response to each other but make no progress. |
| Starvation | A process waits indefinitely because others are always favored; aging is a common remedy. |
| Ostrich Algorithm | Ignoring deadlock on the assumption that it is rare and the cost of handling it is not worth paying. |
Fields
The shape of this dataset, read from the data itself: every column, its type and a real value. Agents can use this to plan a query without fetching the whole document.
| Section | Field | Type | Example |
|---|---|---|---|
| data | concept | string | Mutual Exclusion |
| data | description | string | At least one resource must be non-sharable. |
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