Controlling Thread Attributes and Synchronization

• Threads and synchronization variables can have several attributes associated with them.
  • Different threads may be scheduled differently (round-robin, prioritized, etc.),
  • They may have different stack sizes, and so on.
  • A synchronization variable such as a mutex-lock may be of different types.
• An attributes object is a data-structure that describes entity (thread, mutex, condition variable) properties.
• When creating a thread or a synchronization variable, we can specify the attributes object that determines the properties of the entity.
• Pthreads allows the user to change the priority of the thread.
• Subsequent changes to attributes objects do not change the properties of entities created using the attributes object prior to the change.

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There are several advantages of using attributes objects.

1

It separates the issues of program semantics and implementation.

• Thread properties are specified by the user.
• How these are implemented at the system level is transparent to the user.
• This allows for greater portability across operating systems.

2

Using attributes objects improves modularity and readability of the programs.

3

It allows the user to modify the program easily.

• For instance, if the user wanted to change the scheduling from round robin to time-sliced for all threads,
• they would only need to change the specific attribute in the attributes object.

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To create an attributes object with the desired properties,

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we must first create an object with default properties and then modify the object as required.