Testing Concurrent Programs - Java Concurrency in Practice - page 305

Listing 12.13. Driver Programfor TimedPutTakeTest .
12.2.2. Comparing Multiple Algorithms
While BoundedBuffer is a fairly solid implementation that performs reasonably well,
it turns out to be no match for either ArrayBlockingQueue or LinkedBlockin-
gQueue (which explains why this buffer algorithm wasn't selected for inclusion in the class
library). The java.util.concurrent algorithms have been selected and tuned, in part
using tests just like those described here, to be as efficient as we know how to make them,
while still offering a wide range of functionality. [6] The main reason BoundedBuffer
fares poorly is that put and take each have multiple operations that could encouter conten-
tion—acquire a semaphore, acquire a lock, release a semaphore. Other implementation ap-
proaches have fewer points at which they might contend with another thread.
Figure 12.2 shows comparative throughput on a dual hyperthreaded machine for all three
classes with 256-element buffers, using a variant of TimedPutTakeTest . This test sug-
gests that LinkedBlockingQueue scales better than ArrayBlockingQueue . This
may seem odd at first: a linked queue must allocate a link node object for each insertion,
and hence seems to be doing more work than the array-based queue. However, even though