jnr-process

The jnr-process library provides a drop-in replacement for the JDK ProcessBuilder API, but instead of a thread-pumped shim it is a direct abstraction around the posix_spawn C API and provides selectable in, out, and err channels.

Usage

Basic usage with selectable input (out from child) is shown below:

    @Test
    public void testSelectableIn() throws Exception {
        ProcessBuilder pb = new ProcessBuilder("/bin/sh", "-c", "echo hello");

        Process p = pb.start();

        SelectableChannel in = p.getIn();

        in.configureBlocking(false);
        Selector selector = in.provider().openSelector();
        SelectionKey key = in.register(selector, SelectionKey.OP_READ);
        int selected = selector.select();

        assertEquals(1, selected);
        assertEquals(key, selector.keys().iterator().next());

        selector.close();
        in.configureBlocking(true);

        byte[] hello = new byte[5];
        p.getInputStream().read(hello);

        assertEquals(0, p.waitFor());

        assertArrayEquals("hello".getBytes(), hello);
    }

jnr-process provides getIn, getOut, and getErr to get a SelectableChannel for the child's output, input, and error streams respectively.

The killProcessGroup methods are provided to kill an entire subtree of child processes. All kill forms also accept an optional integer signal to send.