This is the second part of the Concurrency series. For your convenience you can find other parts in the table of contents in Part 1 – Mutex performance in .NET

Today we explore system-wide lock in Java 1.8.0_161 on Windows 10 x64.

There is no built-in mechanism in Java for acquiring system wide lock. One trick is to lock a file — if only every interested process locks the same file, we effectively have a system-wide lock for our processes.

Code

As in previous part, nothing magical. Just a lock, measuring time and showing results.

Results

    \[ \begin{array}{cc} Number\ of\ processes & Time [ms] \\ 1 & 320\\ 2 & 641\\ 3 & 1784\\ 4 & 2277\\ 5 & 2897\\ 6 & 3351\\ 7 & 3929\\ 8 & 4541\\ 9 & 5188\\ 10 & 5815\\ \end{array} \]

As we can see, even for one process this lock type is much slower than mutex in previous part.