Poco::ThreadPool

Poco::ThreadPool提供线程池功能，减少线程的创建和销毁所带来的开销，适合在服务器上应用。创建线程池时指定最少运行线程数和线程池的最大容量，若不指定则采用默认值，取2和16 。线程池的实现机制：有一部分线程始终处于运行状态，但阻塞在Event的wait调用上，所以处于休眠状态，开销并不大。如果我们需要一个线程来运行一段代码（在Poco中，用Runnable的子类表示一个target），则从线程池中去除一个线程，并将这段代码赋给它，并触发Event。然后线程就继续运行了。



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demo

[cpp]
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void ThreadPoolTest::testThreadPool()
{
ThreadPool pool(2, 3, 3);

assert (pool.allocated() == 2);
assert (pool.used() == 0);
assert (pool.capacity() == 3);
assert (pool.available() == 3);
pool.addCapacity(1);
assert (pool.allocated() == 2);
assert (pool.used() == 0);
assert (pool.capacity() == 4);
assert (pool.available() == 4);

RunnableAdapter<ThreadPoolTest> ra(*this, &ThreadPoolTest::hello);
pool.start(ra);
assert (pool.allocated() == 2);
assert (pool.used() == 1);
assert (pool.capacity() == 4);
assert (pool.available() == 3);

pool.start(ra);
assert (pool.allocated() == 2);
assert (pool.used() == 2);
assert (pool.capacity() == 4);
assert (pool.available() == 2);

pool.start(ra);
assert (pool.allocated() == 3);
assert (pool.used() == 3);
assert (pool.capacity() == 4);
assert (pool.available() == 1);

pool.start(ra);
assert (pool.allocated() == 4);
assert (pool.used() == 4);
assert (pool.capacity() == 4);
assert (pool.available() == 0);
}

void ThreadPoolTest::testThreadPool()
{
	ThreadPool pool(2, 3, 3);

	assert (pool.allocated() == 2);
	assert (pool.used() == 0);
	assert (pool.capacity() == 3);
	assert (pool.available() == 3);
	pool.addCapacity(1);
	assert (pool.allocated() == 2);
	assert (pool.used() == 0);
	assert (pool.capacity() == 4);
	assert (pool.available() == 4);

	RunnableAdapter<ThreadPoolTest> ra(*this, &ThreadPoolTest::hello);
	pool.start(ra);
	assert (pool.allocated() == 2);
	assert (pool.used() == 1);
	assert (pool.capacity() == 4);
	assert (pool.available() == 3);

	pool.start(ra);
	assert (pool.allocated() == 2);
	assert (pool.used() == 2);
	assert (pool.capacity() == 4);
	assert (pool.available() == 2);

	pool.start(ra);
	assert (pool.allocated() == 3);
	assert (pool.used() == 3);
	assert (pool.capacity() == 4);
	assert (pool.available() == 1);

	pool.start(ra);
	assert (pool.allocated() == 4);
	assert (pool.used() == 4);
	assert (pool.capacity() == 4);
	assert (pool.available() == 0);
}

线程池的内存策略有点像MemoryPool，请参加/article/1355316.html