问题描述
有没有办法在java中执行一个没有使用ProcessBuilder的启动开销（慢）的命令？
Is there a way to execute a command in java that doesn't suffer from the startup overhead (slowness) of using ProcessBuilder?
更多细节：我正在使用im4java是一个java库，它在内部使用ProcessBuilder来执行imagemagick的程序。这很慢。我创建了一个小单元测试，显示ProcessBuilder（不是im4java）是问题所在。缓慢是使用ProcessBuilder的启动开销。我发现互联网上有帖子说过程序员有开销，所以不仅仅是我这么说。
More detail: I am using im4java which is a java library that internally uses ProcessBuilder to execute imagemagick's programs. It is slow. I have created a small unit test that shows that ProcessBuilder (not im4java) is the problem. The slowness is the startup overhead of using ProcessBuilder. I have found posts around the internet saying processbuider has overhead so its not just me saying it does.
List<String> commands = new ArrayList<String>();
commands.add("C:\\PROGRA~2\\ImageMagick-6.6.4-Q16\\convert.exe");
commands.add("dog.jpg");
commands.add("output.jpg");
ProcessBuilder processBuilder = new ProcessBuilder(commands);
Process start = processBuilder.start();
start.waitFor();
推荐答案
这不推荐，但你可以写一个JNI库可以执行与ProcessBuilder相同的操作。也许你会更快，但我不会指望它，加上你会失去跨平台的兼容性。
This is not recommended, but you could write a JNI library to do the same thing that ProcessBuilder is doing. Perhaps yours would be faster, but I wouldn't count on it, plus you would lose cross-platform compatibility.
我们在这里说话的速度有多慢？我正在使用 ProcessBuilder 来运行Git命令（还没有机会查看JGit），而且看起来很活泼。你可能在Linux上有更好的运气，因为开销可能实际上是在Windows重量级进程创建中。
How slow are we talking here? I'm using ProcessBuilder myself for running Git commands (haven't had a chance to look into JGit yet), and it seems snappy enough. You may have better luck on Linux, as the overhead may actually be in Windows heavyweight process creation.
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