Sets (union/intersection) and itertools - Jaccard coefficient and shingling to check plagiarismĬlasses and Instances (_init_, _call_, etc.)īits, bytes, bitstring, and constBitStream Strings - Escape Sequence, Raw String, and Slicingįormatting Strings - expressions and method calls Object Types - Numbers, Strings, and None Running Python Programs (os, sys, import) Using locks in the with statement - context managerĬondition objects with producer and consumer
RLock (Reentrant) objects - acquire() method Lock objects - acquire() & release() methods Subclassing & overriding run() and _init_() methods Python Multithread Creating a thread and passing arguments to the thread Here it is used just to hold the names of the active threads to show that only 10 are running concurrently. A real resource pool would allocate a connection or some other value to the newly active thread, and reclaim the value when the thread is done. In the code, the ThreadPool class tracks which threads are able to run at a given moment. T = threading.Thread(target=f, name='thread_'+str(i), args=( s, pool)) Name = threading.currentThread().getName()
Semaphores are also often used to guard resources with limited capacity, for example, a database server.įormat='(%(threadName)-9s) %(message)s',) There are many cases we may want to allow more than one worker access to a resource while still limiting the overall number of accesses.įor example, we may want to use semaphore in a situation where we need to support concurrent connections/downloads. The counter can never go below zero when acquire() finds that it is zero, it blocks, waiting until some other thread calls release(). Dijkstra (he used the names P() and V() instead of acquire() and release())Ī semaphore manages an internal counter which is decremented by each acquire() call and incremented by each release() call. This is one of the oldest synchronization primitives in the history of computer science, invented by the early Dutch computer scientist Edsger W.
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