Sent from my phone
On May 13, 2014 6:46 PM, "David Holmes" <david.hol...@oracle.com
<mailto:david.hol...@oracle.com>> wrote:
Hi Aleksej,
Thanks for the doc references regarding abandonment.
Let me rephrase my question. What is this logic trying to
achieve by
waiting on both a mutex and an event? Do we already own the
mutex
when this function is called?
David
On 13/05/2014 11:19 PM, Aleksej Efimov wrote:
David,
The Windows has a different terminology for mutex
objects (much
differs
from the POSIX one). This one link gave me some
understanding of
it [1].
Here is the MSDN [1] description of what "abandoned
mutex" is:
" If a thread terminates without releasing its
ownership of a
mutex
object, the mutex object is considered to be abandoned. A
waiting thread
can acquire ownership of an abandoned mutex object, but
the wait
function will return*WAIT_ABANDONED*to indicate that
the mutex
object is
abandoned. An abandoned mutex object indicates that an
error has
occurred and that any shared resource being protected
by the
mutex
object is in an undefined state. If the thread proceeds as
though the
mutex object had not been abandoned, it is no longer
considered
abandoned after the thread releases its ownership. This
restores
normal
behavior if a handle to the mutex object is subsequently
specified in a
wait function."
What does it mean to wait on mutex and ownership of the
mutex
object:
"Any thread with a handle to a mutex object can use one of
thewait
functions
<http://msdn.microsoft.com/en-__gb/library/windows/desktop/__ms687069%28v=vs.85%29.aspx
<http://msdn.microsoft.com/en-gb/library/windows/desktop/ms687069%28v=vs.85%29.aspx>>to
request ownership of the mutex object. If the mutex
object is
owned by
another thread, the wait function blocks the requesting
thread
until the
owning thread releases the mutex object using
the*ReleaseMutex*
<http://msdn.microsoft.com/en-__gb/library/windows/desktop/__ms685066%28v=vs.85%29.aspx
<http://msdn.microsoft.com/en-gb/library/windows/desktop/ms685066%28v=vs.85%29.aspx>>__function."
How we can release mutex and wait on already owned mutex:
" After a thread obtains ownership of a mutex, it can
specify
the same
mutex in repeated calls to the wait-functions
<http://msdn.microsoft.com/en-__gb/library/windows/desktop/__ms687069%28v=vs.85%29.aspx
<http://msdn.microsoft.com/en-gb/library/windows/desktop/ms687069%28v=vs.85%29.aspx>>__without
blocking its execution. This prevents a thread from
deadlocking
itself
while waiting for a mutex that it already owns. To
release its
ownership
under such circumstances, the thread must
call*ReleaseMutex*
<http://msdn.microsoft.com/en-__gb/library/windows/desktop/__ms685066%28v=vs.85%29.aspx
<http://msdn.microsoft.com/en-gb/library/windows/desktop/ms685066%28v=vs.85%29.aspx>>__once
for each time that the mutex satisfied the conditions
of a wait
function."
[1]
http://msdn.microsoft.com/en-__gb/library/windows/desktop/__ms684266(v=vs.85).aspx
<http://msdn.microsoft.com/en-gb/library/windows/desktop/ms684266(v=vs.85).aspx>
-Aleksej
On 05/13/2014 04:00 PM, David Holmes wrote:
I don't understand this one at all. What is an
"abandoned
mutex"? For
that matter why does the code wait on a mutex and
an event?
Do we
already own the mutex? If so what does it mean to
wait on
it? If not
then how can we release it?
???
Thanks,
David
On 13/05/2014 8:57 PM, Alan Bateman wrote:
This is debugger's shared memory transport so
cc'ing
serviceability-dev
as that is there this code is maintained.
Is there a test case or any outline of the
conditions
that cause this? I
think that would be useful to understand the issue
further.
-Alan
On 13/05/2014 11:46, Aleksej Efimov wrote:
Hi,
Can I have a review for 8032901 bug [1] fix
[2].
There is a possible
case when 'WaitForMultipleObjects' function
can
return the
WAIT_ABANDONED_0 [3] error value.
In such case it's better to release the
mutex and
return error value.
This will prevent other threads to be
blocked on
abandoned mutex.
Thank you,
Aleksej
[1]
https://bugs.openjdk.java.net/__browse/JDK-8032901
<https://bugs.openjdk.java.net/browse/JDK-8032901>
[2]
http://cr.openjdk.java.net/~__aefimov/8032901/9/webrev.00/
<http://cr.openjdk.java.net/~aefimov/8032901/9/webrev.00/>
[3]
http://msdn.microsoft.com/en-__gb/library/windows/desktop/__ms687025(v=vs.85).aspx
<http://msdn.microsoft.com/en-gb/library/windows/desktop/ms687025(v=vs.85).aspx>
