Child Process resource cleanup

Question

the problem I am having in my application is that resources are "leaking" (but not really) because memory is not used a lot (all the work is done by child processes) but since Process class does not have any means to explicitly release system resources taken by .exec, I ended up having a bug (.exec would fail after a while). Only after adding rtm.gc() the application worked as expected.
I have code something like this:
final Runtime rtm = Runtime.getRuntime();
try {
Thread.sleep(5000);
for (int i = 0; i != 100; ++i) {
Process prc = rtm.exec(new String[] {
          "cmd.exe", "/C","\"echo hello\""                     });
Thread.sleep(1000);
prc.waitFor();
rtm.gc(); // without this, it will NOT release resources
System.out.println("finished");
Thread.sleep(20000);
} catch (Exception e) { 
qeustion is: is there not a way to release child process' resources without having to call garbage collection?

Answer 1

My child process does terminates correctly.
It looks like Process object is not freeing up resources it holds for the process (input/output/err streams and process handle itself). Since gc does not kick in (there is almost no memory consumption), it takes a long time until it's cleaned up (if ever)
Adding:
prc.getOutputStream().flush();
prc.getOutputStream().close();
prc.getInputStream().close();
prc.getErrorStream().close();
after
prc.waitFor();
changes things a bit, it reduces number of handles process still holds (after the child process has finished execution) to 1. There is still, however, one handle held by the Process object, my guess is - process handle.
It is a pitty there is no way to "tell" process object to release this one last handle. Or maybe there is?