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Hi Yasumasa,
On 7/10/19 23:56, Yasumasa Suenaga wrote:
Hi Serguei,
Hi
Yasumasaa,
It looks good to me in general.
It is hard to prove the Attach Listener initialization
state machine is fully correct.
One comment though.
+bool AttachListener::check_socket_file() {
. . .
+ is_init_trigger();
+ return true;
+ }
+ return false;
+}
I was expecting a value from the is_init_trigger() call be returned:
return is_init_trigger();
Do I miss anything here?
I expect check_socket_file() returns whether
is_init_trigger() was kicked. So I return true at this point.
Should this function return the result of
is_init_trigger()?
It is not clear to me what is your intention.
Is it Okay for the check_socket_file() to return true even if the
is_init_trigger() returned false?
Thanks,
Serguei
Thanks,
Yasumasa
Thanks,
Serguei
On 7/10/19 17:18, Yasumasa Suenaga wrote:
Hi Chris,
Thank you for your comment!
I uploaded new webrev:
http://cr.openjdk.java.net/~ysuenaga/JDK-8225690/webrev.01/
I write some comments the following.
On 2019/07/11 4:29, Chris Plummer wrote:
Hi Yasumasa,
I just took a quick look at this. I understand a
little about how the attach mechanism works, but am
by no means an expert, and find myself easily lost
in some of the logic. I'll look again after others
have also contributed comments. Here area few
comments.
I don't understand the need for the following in
attach_listener_thread_entry()
428 AttachListener::set_state(AL_NOT_INITIALIZED);
There is no path to this statement since the only
way out of the loop is the following:
I agree with you, but I think we need to reset the
status of Attach Listener
in the end of the function.
We might be able to use ShouldNotReachHere() at here.
How are errors in
AttachListener::init() properly propagated. I see
is_init_trigger() does the following:
548 if
(os::Posix::matches_effective_uid_or_root(st.st_uid))
{
549 init();
550 log_trace(attach)("Attach triggered by
%s", fn);
551 return true;
So "true" is returned even though init() maybe have
failed, but then check_socket_file() doesn't even
check the result from is_init_trigger():
509 is_init_trigger();
510 return true;
The SIGBREAK code does check the is_init_trigger()
result, but since init() failures are not propagated
to is_init_trigger(), the result may not be
accurate.
In case of Linux, HotSpot has some phase to start
Attach Listener:
1. Check attach file (.attach_pid*) ->
is_init_trigger()
2. Create unix domain socket ->
is_init_trigger()
3. Start Attach Listener thread -> init()
is_init_trigger() returns whether init() is kicked or
not.
OTOH init() is declared as a void function, so we
cannot know
Attach Listener is started.
(We can know it through exception message on the
console, but
it will not handle in HotSpot.)
Thus I thought we can add new field
AttachListener::_state
to know current status of Attach Listener.
Have you done any testing of
the error handling by forcing errors to happen?
Do you mean it is the race of the attach request?
If so, I've added the testcase (ConcAttachTest.java).
If you mean the failure of init() and/or
is_init_trigger(),
I do not have idea how to test it.
The following code needs a
comment to indicate that the current state is
AL_INITIALIZED, and if the socket file was removed
it needs to be recreated and a new socket opened.
379 } else if
(AttachListener::check_socket_file()) {
380 continue;
381 }
I added it in new webrev.
Thanks,
Yasumasa
thanks,
Chris
On 7/4/19 6:27 AM, Yasumasa Suenaga wrote:
Hi all,
Please review this change:
JBS: https://bugs.openjdk.java.net/browse/JDK-8225690
webrev: http://cr.openjdk.java.net/~ysuenaga/JDK-8225690/webrev.00/
This issue has been discussed on [1] and [2].
This webrev passed tests on submit repo
(mach5-one-ysuenaga-JDK-8225690-20190704-1214-3626907).
It includes the fix for JDK-8225193. They relate
each other, so I fix them together.
Thanks,
Yasumasa
[1]
https://mail.openjdk.java.net/pipermail/serviceability-dev/2019-July/028585.html
[2]
https://mail.openjdk.java.net/pipermail/serviceability-dev/2019-June/028418.html
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