Latest version including work on the spec language:
http://cr.openjdk.java.net/~robm/4244896/webrev.04/
<http://cr.openjdk.java.net/%7Erobm/4244896/webrev.03/>
-Rob
On 10/05/12 19:56, Rob McKenna wrote:
Hi folks,
The latest version is at:
http://cr.openjdk.java.net/~robm/4244896/webrev.03/
<http://cr.openjdk.java.net/%7Erobm/4244896/webrev.03/>
Feedback greatly appreciated.
-Rob
On 19/04/12 12:05, Alan Bateman wrote:
On 19/04/2012 01:05, David Holmes wrote:
On 18/04/2012 11:44 PM, Jason Mehrens wrote:
Rob,
It looks like waitFor is calling Object.wait(long) without owning
this objects monitor. If I pass Long.MAX_VALUE to waitFor,
shouldn't waitFor return if the early if the process ends?
Also waitFor doesn't call wait() under the guard of a looping
predicate so it will suffer from lost signals and potentially
spurious wakeups. I also don't see anything calling notify[All] to
indicate the process has now terminated. It would appear that
wait(timeout) is being used as a sleep mechanism and that is wrong
on a number of levels.
I assume waitFor(timout) will require 3 distinct implementations, one
for Solaris/Linux/Mac, another for Windows, and a default
implementations for Process implementations that exist outside of the
JDK.
It's likely the Solaris/Linux/Mac implementation will involve two
threads, one to block in waitpid and the other to interrupt it via a
signal if the timeout elapses before the child terminates. The
Windows implementation should be trivial because it can be a timed wait.
I assume the default implementation (which is what is being discussed
here) will need to loop calling exitValue until the timeout elapses
or the child terminates. Not very efficient but at least it won't be
used when when creating Processes via Runtime.exec or ProcessBuilder.
I think the question we need to consider is whether waitFor(timeout)
is really needed. If it's something that it pushed out for another
day then it brings up the question as to whether to include isAlive
now or not (as waitFor without timeout gives us an isAlive equivalent
too).
-Alan.
