pthread_rwlock_trywrlock()
by Tracey Hughes, Cameron Hughes
Professional Multicore Programming: Design and Implementation for C++ Developers
- Copyright
- About the Authors
- Credits
- Acknowledgments
- Introduction
- 1. The New Architecture
- 2. Four Effective Multicore Designs
- 2.1. The AMD Multicore Opteron
- 2.2. The Sun UltraSparc T1 Multiprocessor
- 2.3. The IBM Cell Broadband Engine
- 2.4. Intel Core 2 Duo Processor
- 2.5. Summary
- 3. The Challenges of Multicore Programming
- 3.1. What Is the Sequential Model?
- 3.2. What Is Concurrency?
- 3.3. Software Development
- 3.3.1. Challenge #1: Software Decomposition
- 3.3.2. Challenge #2: Task-to-Task Communication
- 3.3.3. Challenge #3: Concurrent Access to Data or Resources by Multiple Tasks or Agents
- 3.3.4. Challenge #4: Identifying the Relationships between Concurrently Executing Tasks
- 3.3.5. Challenge #5: Controlling Resource Contention Between Tasks
- 3.3.6. Challenge #6: How Many Processes or Threads Are Enough?
- 3.3.7. Challenges #7 and #8: Finding Reliable and Reproducible Debugging and Testing
- 3.3.8. Challenge #9: Communicating a Design That Has Multiprocessing Components
- 3.3.9. Challenge #10: Implementing Multiprocessing and Multithreading in C++
- 3.4. C++ Developers Have to Learn New Libraries
- 3.5. Processor Architecture Challenges
- 3.6. Summary
- 4. The Operating System's Role
- 4.1. What Part Does the Operating System Play?
- 4.1.1. Providing a Consistent Interface
- 4.1.2. Managing Hardware Resources and Other Software Applications
- 4.1.3. The Developer's Interaction with the Operating System
- 4.1.4. Core Operating System Services
- 4.1.5. The Application Programmer's Interface
- 4.2. Decomposition and the Operating System's Role
- 4.3. Hiding the Operating System's Role
- 4.4. Summary
- 4.1. What Part Does the Operating System Play?
- 5. Processes, C++ Interface Classes, and Predicates
- 5.1. We Say Multicore, We Mean Multiprocessor
- 5.2. What Is a Process?
- 5.3. Why Processes and Not Threads?
- 5.4. Using posix_spawn()
- 5.5. Who Is the Parent? Who Is the Child?
- 5.6. Processes: A Closer Look
- 5.7. Monitoring Processes with the ps Utility
- 5.8. Setting and Getting Process Priorities
- 5.9. What Is a Context Switch?
- 5.10. The Activities in Process Creation
- 5.11. Working with Process Environment Variables
- 5.12. Using system() to Spawn Processes
- 5.13. Killing a Process
- 5.14. Process Resources
- 5.15. What Are Asynchronous and Synchronous Processes
- 5.16. The wait() Function Call
- 5.17. Predicates, Processes, and Interface Classes
- 5.18. Summary
- 6. Multithreading
- 6.1. What Is a Thread?
- 6.2. Comparing Threads to Processes
- 6.3. Setting Thread Attributes
- 6.4. The Architecture of a Thread
- 6.5. A Simple Threaded Program
- 6.6. Creating Threads
- 6.7. Managing Threads
- 6.8. Extending the Thread Interface Class
- 6.9. Summary
- 7. Communication and Synchronization of Concurrent Tasks
- 7.1. Communication and Synchronization
- 7.1.1. Dependency Relationships
- 7.1.2. Counting Tasks Dependencies
- 7.1.3. What Is Interprocess Communication?
- 7.1.4. What Are Interthread Communications?
- 7.2. Synchronizing Concurrency
- 7.2.1. Types of Synchronization
- 7.2.2. Synchronizing Access to Data
- 7.2.2.1. Critical Sections
- 7.2.2.2. PRAM Model
- 7.2.2.2.1. Concurrent and Exclusive Memory Access
- 7.2.2.2.2. Concurrent Tasks: Coordinating Order of Execution
- 7.2.2.2.3. Relationships between Cooperating Tasks
- 7.2.2.2.4. Start-to-Start (SS) Relationship
- 7.2.2.2.5. Finish-to-Start (FS) Relationship
- 7.2.2.2.6. Start-to-Finish Relationship
- 7.2.2.2.7. Finish-to-Finish Relationship
- 7.2.3. Synchronization Mechanisms
- 7.2.3.1. Semaphores
- 7.2.3.2. Program Profile 7-4
- 7.2.3.2.1. Program Name:
- 7.2.3.2.2. Description:
- 7.2.3.2.3. Libraries Required:
- 7.2.3.2.4. Headers Required:
- 7.2.3.2.5. Compile and Link Instructions:
- 7.2.3.2.6. Test Environment:
- 7.2.3.2.7. Processors:
- 7.2.3.2.8. Execution Instructions:
- 7.2.3.2.9. Notes:
- 7.2.3.2.10. Mutex Semaphores
- 7.2.3.2.11. Using the Mutex Attribute Object
- 7.2.3.2.12. Using Mutex Semaphores to Manage Critical Sections
- 7.2.3.3. Read-Write Locks
- 7.2.3.4. Program Profile 7-5
- 7.2.3.5. Condition Variables
- 7.2.3.6. Program Profile 7-6
- 7.2.3.7. Thread-Safe Data Structures
- 7.3. Thread Strategy Approaches
- 7.4. Decomposition and Encapsulation of Work
- 7.5. Summary
- 7.1. Communication and Synchronization
- 8. PADL and PBS: Approaches to Application Design
- 8.1. Designing Applications for Massive Multicore Processors
- 8.2. What Is PADL?
- 8.2.1. Layer 5: Application Architecture Selection
- 8.2.1.1. What Are Agents?
- 8.2.1.2. What Is a Multiagent Architecture?
- 8.2.1.3. From Problem Statements to Multiagent Architectures
- 8.2.1.4. Blackboard Architectures
- 8.2.1.5. Approaches to Structuring the Blackboard
- 8.2.1.5.1. A "Question and Answer Browser" Blackboard Example
- 8.2.1.5.2. Where's the Parallelism? Where's the Blackboard?
- 8.2.1.5.3. Components of the Solution
- 8.2.1.5.4. Knowledge Sources for the Browser Program
- 8.2.1.5.5. Is a Blackboard a Good Fit?
- 8.2.1.5.6. The Blackboard as an Iterative Shared Solution Space
- 8.2.1.6. The Anatomy of a Knowledge Source
- 8.2.1.7. Concurrency Flexibility of the Application Architecture
- 8.2.2. Layer 4: Concurrency Models in PADL
- 8.2.3. Layer 3: The Implementation Model of PADL
- 8.2.3.1. C++ Components to the Rescue
- 8.2.3.2. The Intel Threading Building Blocks
- 8.2.3.3. Program Profile 8-1
- 8.2.3.3.1. Program Name:
- 8.2.3.3.2. Description:
- 8.2.3.3.3. Libraries Required:
- 8.2.3.3.4. Additional Source Files Needed:
- 8.2.3.3.5. User-Defined Headers Required:
- 8.2.3.3.6. Compile and Link Instructions:
- 8.2.3.3.7. Test Environment:
- 8.2.3.3.8. Processors:
- 8.2.3.3.9. Notes:
- 8.2.3.3.10. Obtaining the TBB library
- 8.2.3.4. The Parallel STL Library
- 8.2.3.5. The "Implementation Layer" Mapping
- 8.2.3.6. PADL: Layer 3 Type Control Strategies
- 8.2.1. Layer 5: Application Architecture Selection
- 8.3. The Predicate Breakdown Structure (PBS)
- 8.4. Summary
- 9. Modeling Software Systems That Require Concurrency
- 9.1. What Is UML?
- 9.2. Modeling the Structure of a System
- 9.2.1. The Class Model
- 9.2.2. Visualizing Classes
- 9.2.3. Ordering the Attributes and Services
- 9.2.4. Visualizing Instances of a Class
- 9.2.5. Visualizing Template Classes
- 9.2.6. Showing the Relationship between Classes and Objects
- 9.2.7. Visualizing Interface Classes
- 9.2.8. The Organization of Interactive Objects
- 9.3. UML and Concurrent Behavior
- 9.4. Visualizing the Whole System
- 9.5. Summary
- 10. Testing and Logical Fault Tolerance for Parallel Programs
- 10.1. Can You Just Skip the Testing?
- 10.2. Five Concurrency Challenges That Must Be Checked during Testing
- 10.3. Failure: The Result of Defects and Faults
- 10.4. How Do You Approach Defect Removal for Parallel Programs?
- 10.4.1. The Problem Statement
- 10.4.2. A Simple Strategy and Rough-Cut Solution Model
- 10.4.3. A Revised Solution Model Using Layer 5 from PADL
- 10.4.4. The PBS of the Agent Solution Model
- 10.5. What Are the Standard Software Engineering Tests?
- 10.5.1. Software Verification and Validation
- 10.5.2. The Code Doesn't Work — Now What?
- 10.5.3. What Is Logical Fault Tolerance?
- 10.5.4. Predicate Exceptions and Possible Worlds
- 10.5.5. What Is Model Checking?
- 10.6. Summary
- A. UML for Concurrent Design
- B. Concurrency Models
- B.1. Interprocess and Interthread Communication
- B.2. Boss/Worker Approach 1 with Threads
- B.3. Boss/Worker Approach 1 with Processes
- B.4. Boss/Worker Approach 2 with Threads
- B.5. Boss/Worker Approach 3 with Threads
- B.6. Peer-to-Peer Approach 1 with Threads
- B.7. Peer-to-Peer Approach 1 with Processes
- B.8. Peer-to-Peer Approach 2 with Threads
- B.9. Peer-to-Peer Approach 2 with Processes
- B.10. Workpile Approach 1
- B.11. Workpile Approach 2
- B.12. Pipeline Approach with Threads
- B.13. Producer/Consumer Approach 1 with Threads
- B.14. Producer/Consumer Approach 2 with Threads
- B.15. Producer/Consumer Approach 3 with Threads
- B.16. Monitor Approach
- B.17. Blackboard Approach with Threads
- B.18. Data Level Parallelism: SIMD Approach
- B.19. Data Level Parallelism: MIMD Approach
- B.20. PRAM Model
- C. POSIX Standard for Thread Management
- pthread_atfork()
- pthread_attr_destroy()
- pthread_attr_getdetachstate()
- pthread_attr_getguardsize()
- pthread_attr_getinheritsched()
- pthread_attr_getschedparam()
- pthread_attr_getschedpolicy()
- pthread_attr_getscope()
- pthread_attr_getstack()
- pthread_attr_getstackaddr()
- pthread_attr_getstacksize()
- pthread_attr_init()
- pthread_attr_setdetachstate()
- pthread_attr_setguardsize()
- pthread_attr_setinheritsched()
- pthread_attr_setschedparam()
- pthread_attr_setschedpolicy()
- pthread_attr_setscope()
- pthread_attr_setstack()
- pthread_attr_setstackaddr()
- pthread_attr_setstacksize()
- pthread_cancel()
- pthread_cond_broadcast()
- pthread_cond_destroy()
- pthread_cond_signal()
- pthread_cond_timedwait()
- pthread_condattr_destroy()
- pthread_condattr_getclock()
- pthread_condattr_getpshared()
- pthread_condattr_init()
- pthread_condattr_setclock()
- pthread_condattr_setpshared()
- pthread_create()
- pthread_detach()
- pthread_equal()
- pthread_exit()
- pthread_getconcurrency()
- pthread_getcpuclockid()
- pthread_getschedparam()
- pthread_getspecific()
- pthread_join()
- pthread_kill()
- pthread_mutex_destroy()
- pthread_mutex_getprioceiling()
- pthread_mutex_init()
- pthread_mutex_lock()
- pthread_mutex_setprioceiling()
- pthread_mutex_timedlock()
- pthread_mutex_trylock()
- pthread_mutexattr_destroy()
- pthread_mutexattr_getprioceiling()
- pthread_mutexattr_getprotocol()
- pthread_mutexattr_getpshared()
- pthread_mutexattr_gettype()
- pthread_mutexattr_init()
- pthread_mutexattr_setprioceiling()
- pthread_mutexattr_setprotocol()
- pthread_mutexattr_setpshared()
- pthread_mutexattr_settype()
- pthread_once()
- pthread_rwlock_destroy()
- pthread_rwlock_rdlock()
- pthread_rwlock_timedrdlock()
- pthread_rwlock_timedwrlock()
- pthread_rwlock_tryrdlock()
- pthread_rwlock_trywrlock()
- pthread_rwlock_unlock()
- pthread_rwlock_wrlock()
- pthread_rwlockattr_destroy()
- pthread_rwlockattr_getpshared()
- pthread_rwlockattr_init()
- pthread_rwlockattr_setpshared()
- pthread_self()
- pthread_setcancelstate()
- pthread_setconcurrency()
- pthread_setschedparam()
- Pthread_setschedprio()
- pthread_setspecific()
- pthread_testcancel()
- D. POSIX Standard for Process Management
- posix_spawn()
- posix_spawn_file_actions_addclose()
- posix_spawn_file_actions_adddup2()
- posix_spawn_file_actions_addopen()
- posix_spawn_file_actions_destroy()
- posix_spawnattr_destroy()
- posix_spawnattr_getflags()
- posix_spawnattr_getpgroup()
- pisix_spawnattr_getschedparam()
- posix_spawnattr_getschedpolicy()
- Bibliography
Name
SYNOPSIS
THR #include <pthread.h>
int pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock);
int pthread_rwlock_wrlock(pthread_rwlock_t *rwlock);DESCRIPTION
The pthread_rwlock_trywrlock() function shall apply a write lock like the pthread_rwlock_wrlock() function, with the exception that the function shall fail if any thread currently holds rwlock (for reading or writing).
The pthread_rwlock_wrlock() function shall apply a write lock to the read-write lock referenced by rwlock. The calling thread acquires the write lock if no other thread (reader or writer) holds the read-write lock rwlock. Otherwise, the thread shall block until it can acquire the lock. The calling thread may deadlock if at the time the call is made it holds the read-write lock (whether a read or write lock).
Implementations may favor writers over readers to avoid writer starvation.
Results are undefined if any of these functions are called with an uninitialized read-write lock.
If a signal is delivered to a thread waiting for a read-write lock for writing, upon return from the signal handler the thread resumes waiting for the read-write lock for writing as if it was not interrupted.
RETURN VALUE
The pthread_rwlock_trywrlock() function shall return zero if the lock for writing on the read-write lock object referenced by rwlock is acquired. Otherwise, an error number shall be returned to indicate the error.
If successful, the pthread_rwlock_wrlock() function shall return zero; otherwise, an error number shall be returned to indicate the error.
ERRORS
The pthread_rwlock_trywrlock() function shall fail if:
[EBUSY] | The read-write lock could not be acquired for writing because it was already locked for reading or writing. |
The pthread_rwlock_trywrlock() and pthread_rwlock_wrlock() functions may fail if:
[EINVAL] | The value specified by rwlock does not refer to an initialized read-write lock object. |
The pthread_rwlock_wrlock() function may fail if:
[EDEADLK] | The current thread already owns the read-write lock for writing or reading. |
These functions shall not return an error code of [EINTR],
APPLICATION USAGE
Applications using these functions may be subject to priority inversion, as discussed in the Base Definitions volume of IEEE Std 1003.1-2001, Section 3.285, Priority Inversion.
SEE ALSO
pthread_rwlock_destroy(), pthread_rwlock_rdlock(), pthread_rwlock_timedrdlock(), pthread_rwlock_ttimedwrlock(), pthread_rwlock_tryrdlock(), pthread_rwlock_unlock(), the Base Definitions volume of IEEE Std 1003.1-2001, <pthread.h>
Issue 6
The following changes are made for alignment with IEEE Std 1003.lj-2000:
The margin code in the SYNOPSIS is changed to THR to indicate that the functionality is now part of the Threads option (previously it was part of the Read-Write Locks option in IEEE Std 1003.lj-2000 and also part of the XSI extension).
The [EDEADLK] error is deleted as a pthread_rwlock_trywrlock() error.
The SEE ALSO section is updated.
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