On 12/09/2014 01:39 AM, Stuart Marks wrote:
On 12/8/14 12:35 PM, Jaroslav Bachorik wrote:
Please, review the following test change
Issue : https://bugs.openjdk.java.net/browse/JDK-8066708
Webrev: http://cr.openjdk.java.net/~jbachorik/8066708/webrev.00
The test fails very intermittently when RMI registry is trying to bind
to a port
previously used in the test (via ServerSocket).
This seems to be caused by the sockets created via `new
ServerSocket(0)` and
being in reusable mode. The fix attempts to prevent this by explicitly
forbidding the reusable mode.
Hi Jaroslav,
I happened to see this fly by, and there are (I think) some similar
issues going on in the RMI tests.
But first I'll note that I don't think setReuseAddress() will have the
effect that you want. Typically it's set to true before binding a
socket, so that a subsequent bind operation will succeed even if the
address/port is already in use. ServerSockets created with new
ServerSocket(0) are already bound, and I'm not sure what calling
setReuseAddress(false) will do on such sockets. The spec says behavior
is undefined, but my bet is that it does nothing.
I guess it doesn't hurt to try this out to see if it makes a difference,
but I don't have much confidence it will help.
The potential similarity to the RMI tests is exemplified by JDK-8049202
(sorry, this bug report isn't open) but briefly this tests the RMI
registry as follows:
1. Opens port 1099 using new ServerSocket(1099) [1099 is the default
RMI registry port] in order to ensure that 1099 isn't in use by
something else already;
2. If this succeeds, it immediately closes the ServerSocket.
3. Then it creates a new RMI registry on port 1099.
In principle, this should succeed, yet it fails around 10% of the time
on some systems. The error is "port already in use". My best theory is
that even though the socket has just been closed by a user program, the
kernel has to run the socket through some of the socket states such as
FIN_WAIT_1, FIN_WAIT_2, or CLOSING before the socket is actually closed
and is available for reuse. If a program -- even the same one --
attempts to open a socket on the same port before the socket has reached
its final state, it will get an "already in use error".
If this is true I don't believe that setting SO_REUSEADDR will work if
the socket is in one of these final states. (I remember reading this
somewhere but I'm not sure where at the moment. I can try to dig it up
if there is interest.)
I admit this is just a theory and I'm open to alternatives, and I'm also
open to hearing about ways to deal with this problem.
Could something similar be going on with this JMX test?
Hm, this is exactly what happened with this test :(
The problem is that the port is reported as available while it is still
occupied and RMI registry attempts to start using that port.
If setting SO_REUSEADDR does not work then the only solution would be to
retry the test case when this exception occurs.
-JB-
s'marks
