Fix Thread-Safe Trigger Synchronization
Thread-Safe Trigger Implementation
You are tasked with implementing a thread-safe trigger in Python. This trigger manages an internal boolean flag, which is initially False.
Requirements:
wait(): This method must block the calling thread until the trigger has fired.fire(): This method sets the internal flag toTrueand subsequently wakes all threads currently blocked bywait().- Pre-fired State: If
fire()is invoked before any calls towait(), all future invocations ofwait()should return immediately without blocking. - Concurrency: Multiple threads must be able to call both
wait()andfire()concurrently.
Consider the following code fragment for the fire() method:
self.lock.acquire()
self.lock.release()
self.flag = True
Your task is to determine if this specific fire() implementation is thread-safe. If not, explain in detail what potential issues or race conditions can arise, and then propose a correct, thread-safe implementation approach for the trigger.
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Core dilemma
Correctly implementing a robust, efficient, and deadlock-free thread synchronization primitive (a one-shot event/trigger) using low-level concurrency constructs, specifically addressing race conditions and proper thread signaling.
2 tradeoffs and 2 stress tests locked
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Fix Thread-Safe Trigger Synchronization
Thread-Safe Trigger Implementation
You are tasked with implementing a thread-safe trigger in Python. This trigger manages an internal boolean flag, which is initially False.
Requirements:
wait(): This method must block the calling thread until the trigger has fired.fire(): This method sets the internal flag toTrueand subsequently wakes all threads currently blocked bywait().- Pre-fired State: If
fire()is invoked before any calls towait(), all future invocations ofwait()should return immediately without blocking. - Concurrency: Multiple threads must be able to call both
wait()andfire()concurrently.
Consider the following code fragment for the fire() method:
self.lock.acquire()
self.lock.release()
self.flag = True
Your task is to determine if this specific fire() implementation is thread-safe. If not, explain in detail what potential issues or race conditions can arise, and then propose a correct, thread-safe implementation approach for the trigger.