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Java Concurrency In Practice (2006) Figure 12.1 TimedPutTakeTest

In Figure 12.1 on page 263, I noticed the graph starts with 1.

Then I read the following on page 268:

"Therefore, tests of multithreaded performance should normally be mixed with tests of single-threaded performance, even if you want to measure only single-threaded performance. (This issue does not arise in TimedPutTakeTest because even the smallest test case uses two threads.)"

If the smallest test case uses 2 threads, where does the data for 1 thread in Figure 12.1 come from?

Thanks for your help.

Solution

  • The label Number of threads on Figure 12.1 is misleading.

    It is in fact number of thread pairs:

    ...
for (int pairs = 1; pairs <= 128; pairs *= 2) {
...

    Each TimedPutTakeTest uses 2 threads (single Producer and single Consumer) even for value 1.

    for (int i = 0; i < nPairs; i++) {
    pool.execute(new PutTakeTest.Producer());
    pool.execute(new PutTakeTest.Consumer());
}

    Note: The code in question is available online.