Readers/Writers Problem

• cours magistral
• leçon - matière potentielle : many readers
• expression écrite

1CS377: Operating SystemsComputer Science Lecture 11, page 1 Today: Synchronization forReaders/Writers Problem• An object is shared among may threads, each belonging to one oftwo classes:– Readers: read data, never modify it– Writers: read data and modify it• Using a single lock on the data object is overly restrictive=> Want many readers reading the object at once– Allow only one writer at any point– How do we control access to the object to permit this protocol?• Correctness criteria:– Each read or write of the shared data must happen within a critical section.

• void putdown
• writers solution
• toenter block on mutex
• chopstick
• private int numreaders
• readwrite
• writers
• readers
• block
• int