18 Questions
What led to the prevalence of deadlocks in computer systems?
The introduction of interactive systems
In which type of systems are deadlocks particularly critical?
Real-time systems
What type of resources are commonly involved in deadlocks?
Nonshareable and nonpreemptable resources
What can occur when jobs request and hold files for the duration of their execution?
Deadlock
Which of the following is NOT a characteristic of a deadlock?
Livelock
What can occur when shareable resources are locked, such as disks and databases?
Deadlock
What is the primary cause of a deadlock in a spooling system?
No single job has its entire print output in the spool area
What can lead to a deadlock in a network?
Congestion or filling a large percentage of the I/O buffer space
What is the primary characteristic of livelock?
A process is waiting for a resource, but never gains control of it
Which of the following is a common consequence of a deadlock in a spooling system?
Partially completed output for all jobs
What is the primary reason for deadlocks in disk sharing?
Disks are designed to be shared, leading to an active type of deadlock
What is the term used to describe a situation where a network becomes deadlocked due to congestion or filling a large percentage of its I/O buffer space?
Deadlock Sequence
What is a consequence of locking only a subsection of the database?
Reduced access time
In the scenario where two processes P1 and P2 need to update two records R1 and R2, what is the outcome of the deadlock sequence?
A deadlock occurs between P1 and P2
What is an alternative to using locks to preserve the integrity of the database?
Allow simultaneous updates
What can occur when multiple processes access a shared resource, such as a database or a device?
Deadlock
What is the main concern when using a group of dedicated devices?
Deadlock
What happens when two processes request each other's locked resources, leading to a deadlock?
The processes are blocked indefinitely
Study Notes
Deadlocks in Operating Systems
- Deadlocks became more prevalent with the introduction of interactive systems and dynamic resource sharing.
- Deadlocks can cause critical situations in real-time systems and the OS must prevent or resolve them.
Characteristics of Deadlocks
- Deadlocks occur when non-shareable, non-preemptable resources are allocated to jobs that require other locked resources.
- Deadlocks can also occur on shareable resources that are locked, such as disks and databases.
Seven Cases of Deadlock
Case 1: Deadlocks on File Requests
- Deadlocks can occur when jobs request and hold files for execution, leading to a deadlock.
Case 5: Deadlocks in Spooling
- Deadlocks can occur in spooling systems when no job has entire print output in the spool area, resulting in partially completed output for all jobs.
Case 6: Deadlocks in a Network
- Networks can become deadlocked if they don't have protocols to control message flow, leading to congested networks or filled I/O buffer space.
Case 7: Deadlocks in Disk Sharing
- Disks designed for sharing can create an active type of deadlock, known as livelock, due to busy-waiting processes.
Case 2: Deadlocks in Databases
- Locking subsections of a database can improve access time but increase the possibility of deadlocks.
- Locking individual records can also lead to deadlocks if multiple processes need to access the same record simultaneously.
- Deadlocks can occur when two processes (e.g., P1 and P2) need to update two records (e.g., R1 and R2) simultaneously, leading to a race between processes.
Case 3: Deadlocks in Dedicated Device Allocation
- The use of a group of dedicated devices can also deadlock the system.
Learn about deadlocks in spooling systems, where printer jobs get stuck due to disk space limitations. Understand how partially completed output for all jobs can lead to a deadlock. This quiz is based on the 6th edition of 'Understanding Operating Systems' and covers Case 5.
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