Threads, race conditions, deadlock, mutexes, semaphores, the actor model, async I/O, memory models and amdahl's law.
39 cards · basic cards · AI-written, checked twice. Edit anything.
- What is a thread?
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The smallest unit of execution within a process, capable of running concurrently with other threads in the same process.- Define concurrency.
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The ability of a program to deal with multiple tasks being interleaved in execution, not necessarily executing at the same instant.- Define parallelism.
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Multiple tasks executing truly simultaneously on different physical processors or cores.- What is context switching?
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The process of storing and restoring the state of a thread so the CPU can switch between executing different threads.- What is a critical section?
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A code segment where a thread accesses shared resources and must not be interrupted by other threads.- What is a race condition?
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A bug where the outcome of a program depends on the unpredictable order in which multiple threads execute.- What is mutual exclusion?
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The guarantee that only one thread can execute a critical section at any given time.- What is deadlock?
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A situation where two or more threads are blocked forever, each waiting for the other to release a resource.- List the four Coffman conditions for deadlock.
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Mutual exclusion, hold and wait, no preemption, and circular wait.- How can you prevent deadlock?
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Break at least one Coffman condition, such as using timeouts, resource ordering, lock-free algorithms, or allowing preemption.- What is a mutex?
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A synchronization primitive that acts as a mutual exclusion lock, allowing only one thread to hold it at a time.- How does a mutex work?
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A thread acquires the mutex before entering a critical section and releases it upon exit, blocking other threads that try to acquire it.- What is lock contention?
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The situation where many threads compete to acquire the same lock, causing performance degradation and increased waiting times.- What is a semaphore?
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A synchronization primitive that maintains a counter, allowing threads to increment or decrement it and block if the counter would go negative.- What is a binary semaphore?
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A semaphore with a counter that can only be 0 or 1, functionally equivalent to a mutex.
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