RFR(S): JDK-8157236 - attach on ARMv7 fails with com.sun.tools.attach.AttachNotSupportedException: Unable to open socket file

[Dmitry Samersoff]

David,

Updated webrev is:

http://cr.openjdk.java.net/~dsamersoff/JDK-8157236/webrev.04/

Windows is absolutely different story that requires significant efforts
to reproduce error conditions and test changes. Also it has nothing to
do with ARMv7.

So I would prefer to address windows issues separately either as a part
of JDK-8159799 or as a separate CR.

-Dmitry

On 2016-08-12 03:24, David Holmes wrote:
> Hi Dmitry,
> 
> On 12/08/2016 2:55 AM, Dmitry Samersoff wrote:
>> David,
>>
>> Please see updated webrev.
>>
>> http://cr.openjdk.java.net/~dsamersoff/JDK-8157236/webrev.03/
>>
>> I didn't touch windows version because it quite different from *NIX one.
> 
> Do we ever see failures on Windows? Is so we should add diagnostics
> there too even if they are different to *NIX.
> 
> I would still like to see what file it is working with. We need some
> logging in here:
> 
> bool AttachListener::is_init_trigger() {
>    if (init_at_startup() || is_initialized()) {
>      return false;               // initialized at startup or already
> initialized
>    }
>    char fn[PATH_MAX+1];
>    sprintf(fn, ".attach_pid%d", os::current_process_id());
>    int ret;
>    struct stat64 st;
>    RESTARTABLE(::stat64(fn, &st), ret);
>    if (ret == -1) {
> +    log ("failed to find attach file: %s, trying alternate", fn)
>      snprintf(fn, sizeof(fn), "%s/.attach_pid%d",
>               os::get_temp_directory(), os::current_process_id());
>      RESTARTABLE(::stat64(fn, &st), ret);
> +    if (ret == -1) {
> +       log("failed to find attach file: %s", fn);
> +    }
>    }
> 
> All failure paths need to show us what it was that failed.
> 
> typos: trigerred -> triggered
> 
> Thanks,
> David
> 
>> -Dmitry
>>
>> On 2016-08-08 02:40, David Holmes wrote:
>>> Hi Dmitry,
>>>
>>> On 5/08/2016 7:25 PM, Dmitry Samersoff wrote:
>>>> Everybody,
>>>>
>>>> Please review the fix:
>>>>
>>>>   http://cr.openjdk.java.net/~dsamersoff/JDK-8157236/webrev.02/
>>>>
>>>> Problem:
>>>>   Tests fail intermittently because it can't attach to child process,
>>>>   these attach failures is hard to debug because attach framework
>>>>   doesn't provide enough diagnostic information.
>>>>
>>>> Solution:
>>>>
>>>>   a) Increase attach timeout
>>>>   b) Slightly change attach loop to save a bit of CPU power.
>>>>   c) Add some logging to attach listener.
>>>>
>>>> It's just a first step in this direction. Complete cleanup of attach
>>>> code (remove LinuxThreads support and convert all printing to UL) is
>>>> not
>>>> a goal of this fix - I'll file a separate CR for it.
>>>
>>> I still think you need more logging now to aid in debugging these cases.
>>> In particular we want to be able to verify that the path of the attach
>>> file is what we expect in all cases ie whether we find  the .attach_pid
>>> file in cwd or whether we are looking in temp directory, and whether we
>>> ultimately succeed or fail.
>>>
>>> Plus whatever you do now should be done consistently for all platforms.
>>>
>>> Thanks,
>>> David
>>>
>>>> -Dmitry
>>>>
>>
>>


-- 
Dmitry Samersoff
Oracle Java development team, Saint Petersburg, Russia
* I would love to change the world, but they won't give me the sources.