On 14/11/2011 00:42, David Holmes wrote:
Will the exec'd process block until the copier threads read from its
output streams? If not then the copier threads (well stdin anyway)
could read their input and have terminated before the main thread even
reaches the original sleep() call.
I don't think this test can be written correctly as-is. Even using a
CountDownLatch won't help because you have to sync with two copier
threads, so the first could be finished before the second signals the
latch.
I would think we would need to exec our own process (a Java one of
course) that assists with the synchronization issue - ie by not
terminating until it receives an input token. At least that way we
know the copier threads can not proceed passed the read() calls, even
if we can't be 100% certain they are in the read at the time the
process is destroyed.
The test runs cat without any arguments so the Copier threads will block
when they read from the stream. If we can get the main thread to wait
until the Copier threads are just about to do the read, sleep for a bit,
then the threads should be blocked in the read when we destroy the
process. It's not ideal but I don't think there is any other way to test
this.
-Alan.
