在Java中使用ProcessBuilder执行外部命令时如何提高性能

Question

I use ProcessBuilder class to execute external commands in Java.

The code likes below.

ProcessBuilder pb = new ProcessBuilder(command);
pb.redirectErrorStream(true); 
Process process = pb.start(); 
...
// instance a new thread to read process output
...
process.waitFor(); 
...

But If a lot of commands are used to executed by this approach. As waitFor() would cost plenty time, and command executing time would cost more then Linux command line.

Is there any approach to increase the waitfor() performance, or other efficient approach to executing command in java?

Answer 1

Is there any approach to increase the waitfor() performance,

No.

or other efficient approach to executing command in java?

No.

In fact, assuming that you are reading all of the external command's output, the waitFor() call is unlikely to take much time at all.

First of all, I think you are doing what is known as "premature optimization". That is, you are trying to optimize something before you know that optimization is required. Unless you have gotten your code working, measured its performance, and profiled it, you are only guessing that waitFor() in particular and using ProcessBuilder in general are a significant bottleneck. If your guess is wrong, then optimization is a waste of time.

---

Assuming that that using ProcessBuilder >>is<< a bottleneck, then there is not much you can do about it ... in Java. Possible non-java solutions are:

• Write / rewrite the external application so that you don't need to run multiple commands.

• Write a script or batch file, and get >>that<< to run multiple commands.

Answer 2

You can take a look at NuProcess .

However, the README states:

Speed-wise, there is not a significant difference between NuProcess and the standard Java Process class, even when running 500 concurrent processes. On some platforms such as MacOS X or Linux, NuProcess is 20% faster than java.lang.Process for large numbers of processes.

It may be worth a try and see if it helps in your case.