p.45
Threading Issues: Cancellation, Signal Handling, and Pools
What is a target thread?
A thread that is to be canceled.
p.19
Thread States and Synchronization
What can the processor do when a thread is blocked?
Turn to the execution of another ready thread in the same or a different process.
p.6
Introduction to Threads and Processes
How many threads can exist for each process?
Many threads can exist for each process.
p.51
Scheduler Activations and Lightweight Processes (LWP)
What triggers an upcall when using scheduler activation?
When an application thread is about to block.
p.11
Single vs. Multi-Threaded Processes
What do all threads of a process share?
Access to the shared memory and resources of its process.
p.8
Single vs. Multi-Threaded Processes
What is multithreading in an operating system?
The ability of an OS to support multiple, concurrent paths of execution within a single process.
p.21
Thread States and Synchronization
What do all threads of a process share?
The same address space and other resources.
p.8
Single vs. Multi-Threaded Processes
What is the unit of dispatching in multithreading?
A thread or lightweight process.
p.37
Threading Models: Many-to-One, One-to-One, Many-to-Many
Which operating system supported the two-level model before Solaris 9?
The Solaris operating system.
p.14
Benefits and Drawbacks of Multithreading
How do threads benefit resource sharing?
Threads share the memory and resources of the process they belong to, allowing multiple threads of activity within the same address space.
p.39
OpenMP and Grand Central Dispatch (GCD)
What is OpenMP?
A set of compiler directives and an API for parallel programming in shared-memory environments.
p.41
OpenMP and Grand Central Dispatch (GCD)
What is Grand Central Dispatch (GCD)?
A technology for Apple’s Mac OS X and iOS operating systems that allows parallel code execution.
p.15
Benefits and Drawbacks of Multithreading
What is one benefit of using threads over processes?
It takes less time to create a new thread than a process.
p.18
Thread States and Synchronization
What are the key states for a thread?
Running, Ready, Blocked, Suspend.
p.7
Single vs. Multi-Threaded Processes
What are the two characteristics of traditional processes?
They follow an execution path that may be interleaved with other processes and have an execution state and dispatching priority.
p.27
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
What is one way to overcome the disadvantages of ULT?
By writing an application as multiple processes rather than multiple threads.
p.16
Single vs. Multi-Threaded Processes
What are the two types of work in a single-user system?
Foreground and background work.
p.26
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
What is a major disadvantage of User Level Threads (ULTs) regarding system calls?
When a ULT executes a blocking system call, all threads within the process are blocked.
p.13
Single vs. Multi-Threaded Processes
What components are included in a thread?
Parent Code, Data and Heap, Stack, Program Counter (PC), and CPU Registers.
p.10
Single vs. Multi-Threaded Processes
What is a Java run-time environment characterized by?
A system of one process with multiple threads.
p.16
Benefits and Drawbacks of Multithreading
How does multithreading contribute to program design?
It allows for a modular program structure.
p.7
Single vs. Multi-Threaded Processes
What does the OS provide to prevent unwanted interference between processes?
Protection with respect to resources.
p.10
Single vs. Multi-Threaded Processes
What does the right half of Figure 4.1 depict?
Multithreaded approaches.
p.24
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
What do ULT states refer to?
User-Level Thread states.
p.44
Threading Issues: Cancellation, Signal Handling, and Pools
What are the two types of thread cancellation?
Asynchronous and deferred.
p.24
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
What is depicted in Figure 4.6?
Examples of the relationships between User-Level Thread states and Process states.
p.14
Benefits and Drawbacks of Multithreading
How does multithreading benefit multiprocessor architectures?
It allows threads to run in parallel on different processors, increasing efficiency.
p.21
Thread States and Synchronization
Why is thread synchronization necessary?
To synchronize the activities of various threads.
p.22
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
What are the two types of threads mentioned?
User Level Threads (ULT) and Kernel Level Threads (KLT).
p.43
OpenMP and Grand Central Dispatch (GCD)
What is the purpose of concurrent queues in Grand Central Dispatch (GCD)?
To allow multiple blocks to execute in parallel while maintaining FIFO order.
p.4
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
What are the two main types of threads discussed in the lecture?
User Level Threads and Kernel Level Threads.
p.23
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
Who manages User-Level Threads (ULTs)?
Thread management is done by the application (user level library).
p.25
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
What is one advantage of User Level Threads (ULTs)?
Thread switching does not require kernel mode privileges (no mode switches).
p.20
Single vs. Multi-Threaded Processes
What does multiprogramming enable on a uniprocessor?
The interleaving of multiple threads within multiple processes.
p.30
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
How do KLTs overcome the drawbacks of User Level Threads (ULTs)?
By allowing the kernel to schedule multiple threads from the same process on multiple processors and scheduling another thread if one is blocked.
p.14
Benefits and Drawbacks of Multithreading
What is one major benefit of multithreaded programming related to user interaction?
Responsiveness, allowing a program to continue running even if part of it is blocked.
p.13
Single vs. Multi-Threaded Processes
How does a thread differ from a process?
A thread shares the parent code, data, and heap, while a process has its own separate resources.
p.5
Introduction to Threads and Processes
What is the basic idea of complex systems according to Herbert Simon?
Several components perform particular subfunctions that contribute to the overall function.
p.37
Threading Models: Many-to-One, One-to-One, Many-to-Many
What is the Many-to-Many Model in threading?
A variation that multiplexes many user-level threads to a smaller or equal number of kernel threads, allowing user-level threads to be bound to kernel threads.
p.50
Scheduler Activations and Lightweight Processes (LWP)
What is a key issue in multithreaded programs regarding communication?
Communication between the kernel and the thread library.
p.12
Single vs. Multi-Threaded Processes
What is the primary difference between threads and processes?
Threads are the smallest unit of processing that can be scheduled by an operating system, while processes are independent executing programs.
p.7
Thread Execution and Context Management
How are traditional processes scheduled and dispatched?
By the operating system (OS).
p.43
OpenMP and Grand Central Dispatch (GCD)
What function is used to submit a block to the default-priority concurrent queue in GCD?
dispatch async() function.
p.19
Thread Execution and Context Management
What does a thread need to provide when spawning another thread?
An instruction pointer and arguments for the new thread.
p.36
Threading Models: Many-to-One, One-to-One, Many-to-Many
What does the Many-to-Many model allow?
It allows many user-level threads to be mapped to many kernel threads.
p.27
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
What is the purpose of jacketing in User Level Threads (ULT)?
To convert a blocking system call into a non-blocking system call.
p.9
Single vs. Multi-Threaded Processes
What is a single-threaded approach?
A single execution path per process where the concept of a thread is not recognized.
p.15
Benefits and Drawbacks of Multithreading
What is the time difference in switching between threads versus processes?
Switching between two threads takes less time than switching between processes.
p.28
Threading Issues: Cancellation, Signal Handling, and Pools
What is the purpose of jacketing in thread management?
To convert a blocking system call into a non-blocking system call.
p.23
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
Is the kernel aware of User-Level Threads (ULTs)?
No, the kernel is not aware of the existence of threads.
p.12
Benefits and Drawbacks of Multithreading
What is a key advantage of using threads over processes?
Threads have lower overhead for context switching compared to processes.
p.12
Threading Issues: Cancellation, Signal Handling, and Pools
What is a disadvantage of using threads?
Threads can lead to issues with synchronization and data consistency due to shared memory.
p.17
Thread Execution and Context Management
What occurs when a process is terminated?
All threads within the process are terminated.
p.36
Threading Models: Many-to-One, One-to-One, Many-to-Many
What happens if the number of user-level threads (U) is less than the number of kernel threads (L)?
There are no benefits of multithreading.
p.21
Thread States and Synchronization
How does one thread's alteration of a resource affect others?
Any alteration by one thread affects the other threads in the same process.
p.2
Introduction to Threads and Processes
What is the email address of the instructor?
shamila_nasreen131@yahoo.com.
p.30
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
Can kernel routines be multithreaded?
Yes, kernel routines themselves can be multithreaded.
p.26
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
How does a pure ULT strategy affect multithreaded applications?
It prevents them from taking advantage of multiprocessing.
p.28
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
What is one disadvantage of using multiple processes instead of multiple threads?
It eliminates the main advantage of threads, leading to greater overhead due to process switching.
p.15
Benefits and Drawbacks of Multithreading
How do threads enhance communication between programs?
Threads enhance efficiency in communication between programs.
p.24
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
What are the possible transitions mentioned in the text?
4.6a→4.6b, 4.6a→4.6c, 4.6a→4.6d.
p.48
Threading Issues: Cancellation, Signal Handling, and Pools
What structure can be used to store created threads in a thread pool?
A container such as a queue or any other structure that allows adding and pulling threads.
p.35
Threading Models: Many-to-One, One-to-One, Many-to-Many
How does the one-to-one threading model affect multiprocessor performance?
It provides better multiprocessor performance.
p.30
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
What is a key advantage of Kernel Level Threads (KLTs)?
The kernel can simultaneously schedule multiple threads from the same process on multiple processors.
p.20
Thread Execution and Context Management
When does execution pass from one thread to another on a uniprocessor?
When the currently running thread is blocked or when its time slice is exhausted.
p.15
Benefits and Drawbacks of Multithreading
How does the termination time of a thread compare to that of a process?
It takes less time to terminate a thread than a process.
p.2
Introduction to Threads and Processes
What are the office hours for the instructor?
Wednesday: 8:30 - 10:00 AM, Thursday: 8:30 - 10:00 AM.
p.14
Benefits and Drawbacks of Multithreading
Why is multithreading considered more economical than process creation?
Because threads share resources of the process, making it less costly to create and context-switch threads.
p.33
Threading Models: Many-to-One, One-to-One, Many-to-Many
What is the One-to-One threading model?
A model where each user thread is mapped to a separate kernel thread.
p.34
Threading Models: Many-to-One, One-to-One, Many-to-Many
What is a key advantage of the Many-to-One model?
It is fast and does not require system calls.
p.45
Threading Issues: Cancellation, Signal Handling, and Pools
What is thread cancellation?
Terminating a thread before it has finished.
p.34
Threading Models: Many-to-One, One-to-One, Many-to-Many
What is a major limitation of the Many-to-One model?
There is no parallel execution of threads, which means it can't exploit multiple CPUs.
p.28
Threading Issues: Cancellation, Signal Handling, and Pools
What does the jacket routine do when the blocked thread regains control?
It checks the I/O device again to see if it is available.
p.42
OpenMP and Grand Central Dispatch (GCD)
How do serial queues operate?
Blocks placed on a serial queue are removed in FIFO order and must complete execution before another block is removed.
p.41
OpenMP and Grand Central Dispatch (GCD)
Provide a simple example of a block in GCD.
ˆ { printf("I am a block"); }
p.31
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
What is a disadvantage of Kernel Level Threads (KLTs)?
The transfer of control from one thread to another within the same process requires a mode switch to the kernel.
p.9
Single vs. Multi-Threaded Processes
Which operating systems supported single-threaded processes?
MS-DOS and some versions of UNIX.
p.50
Scheduler Activations and Lightweight Processes (LWP)
What data structure is typically used in the context of scheduling activation?
Lightweight Process (LWP).
p.29
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
Is any thread management done by the application in Kernel-Level Threads?
No, all management is done by the kernel.
p.10
Single vs. Multi-Threaded Processes
Which operating systems support multiple multithreaded processes?
Windows and some UNIX systems.
p.47
Threading Issues: Cancellation, Signal Handling, and Pools
What is a thread pool?
A group of pre-instantiated, idle threads that await work.
p.4
Single vs. Multi-Threaded Processes
What is the difference between single threaded and multi threaded processes?
Single threaded processes have one thread of execution, while multi threaded processes can have multiple threads running concurrently.
p.23
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
Do User-Level Threads (ULTs) require kernel system calls?
Yes, they still require a kernel system call to operate.
p.4
Thread States and Synchronization
What aspect of threads is covered under 'Thread States'?
The various states that threads can be in during their lifecycle.
p.39
OpenMP and Grand Central Dispatch (GCD)
What happens when OpenMP encounters the directive #pragma omp parallel?
It creates as many threads as there are processing cores in the system.
p.4
Thread States and Synchronization
What is thread synchronization?
The coordination of threads to ensure correct execution and data integrity.
p.51
Scheduler Activations and Lightweight Processes (LWP)
What is an upcall in the context of scheduler activation?
A procedure where the kernel informs an application about certain events.
p.19
Thread States and Synchronization
What occurs when the event for which a thread is blocked happens?
The thread is moved to the Ready queue.
p.11
Thread Execution and Context Management
What does TCB stand for in the context of threads?
Thread Control Block, which saves the thread context when not running.
p.25
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
How can scheduling be tailored in User Level Threads?
Scheduling can be application specific.
p.13
Single vs. Multi-Threaded Processes
What components make up a process?
Code, Data, Heap, Stack, Program Counter (PC), Process Control Block (PCB), and CPU Registers.
p.33
Threading Models: Many-to-One, One-to-One, Many-to-Many
What is the Many-to-One threading model?
A model where many user threads are mapped to a single kernel thread.
p.43
OpenMP and Grand Central Dispatch (GCD)
How are the system-wide concurrent dispatch queues distinguished?
According to priority: low, default, and high.
p.46
Threading Issues: Cancellation, Signal Handling, and Pools
What are signals used for in UNIX systems?
To notify a process that a particular event has occurred.
p.49
Threading Issues: Cancellation, Signal Handling, and Pools
What is Thread Specific Data?
It allows each thread to have its own copy of data.
p.33
Threading Models: Many-to-One, One-to-One, Many-to-Many
What is the Many-to-Many threading model?
A model where many user threads are mapped to many kernel threads.
p.42
OpenMP and Grand Central Dispatch (GCD)
What does Grand Central Dispatch (GCD) do?
GCD schedules blocks for run-time execution by placing them on a dispatch queue.
p.50
Scheduler Activations and Lightweight Processes (LWP)
What happens if a kernel thread blocks?
The LWP and the user-level thread attached to it also block.
p.42
OpenMP and Grand Central Dispatch (GCD)
How does GCD assign blocks for execution?
It removes a block from a queue and assigns it to an available thread from the thread pool it manages.
p.36
Threading Models: Many-to-One, One-to-One, Many-to-Many
What can the operating system do in a Many-to-Many model?
Create a sufficient number of kernel threads.
p.12
Single vs. Multi-Threaded Processes
Can threads within the same process communicate easily?
Yes, threads can communicate easily since they share the same memory space.
p.45
Threading Issues: Cancellation, Signal Handling, and Pools
What is asynchronous cancellation?
It terminates the target thread immediately, which can be troublesome if the thread is updating shared data.
p.32
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
What advantage does a combined approach provide regarding blocking system calls?
A blocking system call need not block the entire process.
p.40
OpenMP and Grand Central Dispatch (GCD)
What is OpenMP?
OpenMP is an API that supports multi-platform shared memory multiprocessing programming in C, C++, and Fortran.
p.2
Introduction to Threads and Processes
What department does Engr. Shamila Nasreen belong to?
Department of Software Engineering.
p.50
Scheduler Activations and Lightweight Processes (LWP)
How does the user-thread library perceive a Lightweight Process (LWP)?
As a virtual processor for scheduling user threads.
p.3
Introduction to Threads and Processes
Name one reference book on Operating Systems.
William Stallings, 'Operating Systems'.
p.34
Threading Models: Many-to-One, One-to-One, Many-to-Many
What is the Many-to-One threading model?
Many user-level threads are mapped to a single kernel thread.
p.7
Single vs. Multi-Threaded Processes
What is a key feature of traditional processes in terms of execution?
They are sequential, meaning only one execution path.
p.44
Threading Issues: Cancellation, Signal Handling, and Pools
What is the purpose of thread pools?
To manage a collection of pre-initialized threads for executing tasks.
p.6
Introduction to Threads and Processes
What does a process define?
The address space and general process attributes.
p.23
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
How do User-Level Threads (ULTs) differ from previously discussed threads?
They are managed by the application rather than the kernel.
p.32
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
How are multiple User Level Threads (ULTs) mapped in a combined approach?
They are mapped onto some (smaller or equal) number of Kernel Level Threads (KLTs).
p.49
Threading Issues: Cancellation, Signal Handling, and Pools
What is another term for thread-specific data?
Thread-local storage (TLS).
p.35
Threading Models: Many-to-One, One-to-One, Many-to-Many
What is a drawback of the one-to-one threading model?
Each user thread requires the creation of a kernel thread, which limits the total number of threads.
p.32
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
What is a key benefit of multiple threads running in parallel in a combined approach?
Multiple threads within the same application can run in parallel on multiple processors.
p.17
Thread Execution and Context Management
What maintains most of the state information dealing with execution in a thread?
Thread-level data structures.
p.48
Threading Issues: Cancellation, Signal Handling, and Pools
What is a key requirement for implementing thread pools?
A way to create threads and hold them in an idle state.
p.35
Threading Models: Many-to-One, One-to-One, Many-to-Many
What is the mapping of user-level threads in a one-to-one threading model?
Each user-level thread maps to a kernel thread.
p.49
Benefits and Drawbacks of Multithreading
What is one of the major benefits of using threads?
Most data is shared among threads.
p.46
Threading Issues: Cancellation, Signal Handling, and Pools
What are the options for delivering a signal to a process?
1. Deliver to the specific thread; 2. Deliver to every thread; 3. Deliver to certain threads; 4. Assign a specific thread to receive all signals.
p.49
Threading Issues: Cancellation, Signal Handling, and Pools
When do threads need thread-specific data?
When they require their own unique data separate from other threads.
p.46
Threading Issues: Cancellation, Signal Handling, and Pools
What are the two types of signal handlers?
1. Default signal handler; 2. User-defined signal handler.
p.42
OpenMP and Grand Central Dispatch (GCD)
What are the two types of dispatch queues identified by GCD?
Serial and concurrent queues.
p.51
Scheduler Activations and Lightweight Processes (LWP)
What does the kernel provide to an application in the scheduler activation scheme?
A set of virtual processors (LWPs).
p.48
Threading Issues: Cancellation, Signal Handling, and Pools
What does the execute() method in a thread pool do?
It performs the work and then returns.
p.42
OpenMP and Grand Central Dispatch (GCD)
What is the main queue in GCD?
Each process has its own serial queue known as its main queue.
p.6
Introduction to Threads and Processes
What are processes considered in relation to threads?
Containers in which threads execute.
p.19
Thread Execution and Context Management
What happens when a new process is spawned?
A thread for that process is also spawned.
p.41
OpenMP and Grand Central Dispatch (GCD)
What does GCD combine to facilitate parallel programming?
Extensions to the C language, an API, and a run-time library.
p.39
OpenMP and Grand Central Dispatch (GCD)
What do compiler directives in OpenMP do?
They identify parallel regions as blocks of code that may run in parallel.
p.41
OpenMP and Grand Central Dispatch (GCD)
How does GCD manage threading?
It manages most of the details of threading automatically.
p.51
Scheduler Activations and Lightweight Processes (LWP)
What is the purpose of scheduler activation?
To facilitate communication between the user-thread library and the kernel.
p.41
OpenMP and Grand Central Dispatch (GCD)
What are blocks in the context of GCD?
Self-contained units of work specified in C and C++ languages.
p.48
Threading Issues: Cancellation, Signal Handling, and Pools
What is an example of a standard interface for threads in a thread pool?
An abstract class called Task with an execute() method.
p.41
OpenMP and Grand Central Dispatch (GCD)
How is a block specified in code?
By a caret (^) inserted in front of a pair of braces ({ }).
p.35
Threading Models: Many-to-One, One-to-One, Many-to-Many
Which operating systems use the one-to-one threading model?
Windows NT/XP/2000, Linux, Solaris 9 and later.
p.45
Threading Issues: Cancellation, Signal Handling, and Pools
What is deferred cancellation?
It sets a flag indicating the thread should cancel itself when convenient, allowing periodic checks.
p.51
Scheduler Activations and Lightweight Processes (LWP)
What does the upcall handler do when a thread is blocking?
Saves the state of the blocking thread and schedules another eligible thread.
p.12
Single vs. Multi-Threaded Processes
How do threads share resources compared to processes?
Threads share the same memory space and resources of their parent process, while processes have separate memory spaces.
p.32
User Level Threads (ULT) vs. Kernel Level Threads (KLT)
What is the primary characteristic of thread creation in combined approaches?
Thread creation is done in the user space.
p.48
Threading Issues: Cancellation, Signal Handling, and Pools
How can threads be kept in an idle state in a thread pool?
By having each thread wait at a barrier until the pool hands it work.
p.17
Thread Execution and Context Management
What happens when a process is suspended in a thread-supported OS?
All threads of the process are suspended.
p.44
Threading Issues: Cancellation, Signal Handling, and Pools
What is thread-specific data?
Data that is unique to each thread.
p.19
Thread States and Synchronization
What happens when a thread blocks?
It saves its user registers, program counter, and stack pointers.
p.47
Threading Issues: Cancellation, Signal Handling, and Pools
How does a thread pool help manage the number of threads in an application?
It allows the number of threads to be bound to the size of the pool.
p.49
Threading Models: Many-to-One, One-to-One, Many-to-Many
Which major thread libraries provide support for thread-specific data?
pThreads, Win32, and Java.
p.45
Threading Issues: Cancellation, Signal Handling, and Pools
What is a drawback of asynchronous cancellation?
It can occur at any time, potentially leaving shared data in an inconsistent state.
p.45
Threading Issues: Cancellation, Signal Handling, and Pools
Why is deferred cancellation considered safer?
It allows the target thread to periodically check if it should be canceled, ensuring safe cancellation.
p.40
OpenMP and Grand Central Dispatch (GCD)
What type of programming does OpenMP facilitate?
Shared memory multiprocessing programming.
p.28
Threading Issues: Cancellation, Signal Handling, and Pools
How does a thread utilize a jacket routine for I/O operations?
Instead of directly calling a system I/O routine, a thread calls an application-level I/O jacket routine.
p.47
Threading Issues: Cancellation, Signal Handling, and Pools
Why are thread pools preferred over instantiating new threads for each task?
They prevent the overhead of creating a thread multiple times.
p.28
Threading Issues: Cancellation, Signal Handling, and Pools
What happens if the I/O device is busy when a thread checks it?
The thread enters the Blocked state and passes control to another thread.
p.47
Threading Issues: Cancellation, Signal Handling, and Pools
What is one advantage of using a thread pool?
It is usually slightly faster to service a request with an existing thread than to create a new thread.
p.6
Introduction to Threads and Processes
What does a thread define?
A sequential execution stream within a process.
p.44
Threading Issues: Cancellation, Signal Handling, and Pools
What are scheduler activations?
A mechanism to improve the performance of multithreaded applications by allowing the kernel to manage thread scheduling.
p.6
Introduction to Threads and Processes
Can a thread exist outside of a process?
No, a thread is bound to a single process.
p.11
Single vs. Multi-Threaded Processes
What is one characteristic of a thread in a process?
An execution state (Running, Ready, etc.).
p.19
Thread Execution and Context Management
What is allocated to a new thread when it is spawned?
Its own register context and stack space.
p.36
Threading Models: Many-to-One, One-to-One, Many-to-Many
What occurs if the number of user-level threads (U) is greater than the number of kernel threads (L)?
Some threads may have to wait for a Lightweight Process (LWP) to run.
p.42
OpenMP and Grand Central Dispatch (GCD)
Can developers create additional serial queues in GCD?
Yes, developers can create additional serial queues that are local to particular processes.
p.34
Threading Models: Many-to-One, One-to-One, Many-to-Many
Can you name examples of the Many-to-One threading model?
Solaris Green Threads and GNU Portable Threads.
p.36
Threading Models: Many-to-One, One-to-One, Many-to-Many
Which operating systems are examples of the Many-to-Many model?
Solaris prior to version 9 and Windows NT/2000 with the ThreadFiber package.
p.51
Scheduler Activations and Lightweight Processes (LWP)
What does the kernel do when a thread is about to block?
Makes an upcall to inform the application and allocates a new virtual processor.
p.42
OpenMP and Grand Central Dispatch (GCD)
Why are serial queues useful?
They ensure the sequential execution of several tasks.
p.11
Thread Execution and Context Management
What type of storage is available for local variables in a thread?
Per-thread static storage.
p.51
Scheduler Activations and Lightweight Processes (LWP)
What happens when the event that a blocking thread was waiting for occurs?
The kernel makes another upcall to the thread library informing it.
