RFR: JDK-6546236 Thread interrupt() of Thread.sleep() can be lost on Solaris due to race with signal handler

[Frederic Parain]

Hi Dan,

Thank you very much for your review, I knew it was a painful review with 
all this code moving from one directory to another. I've
in-lined my answers below.

The new webrev is here:
http://cr.openjdk.java.net/~fparain/6546236/webrev.01/

On 02/13/2014 07:14 PM, Daniel D. Daugherty wrote:
>  > http://cr.openjdk.java.net/~fparain/6546236/webrev.00/
>
> Sorry for the delay. This was a difficult review to perform due to
> the code motion between files. My technique was to use the 'udiff'
> view for a side-by-side visual compare. Of course, this means I
> could easily have missed critical differences... :-)
>
> src/os/bsd/vm/os_bsd.cpp
>      Deletes os::sleep(), os::naked_sleep(), os::interrupt() and
>      os::is_interrupted().
>
>      bsd << os::sleep >> posix
>        << assert(!Bsd::supports_monotonic_clock(), "time moving
> backwards");
>        >> warning("time moving backwards");
>            The above diff happens twice. Without at least an assert here
>            we will be less likely to see this issue pop-up on specific
>            test machines.

I've re-written this warning. Now the warning will be printed only
if the JVM was expecting a monotonic clock and its time warps backward.
Note that warnings can be disabled on product builds with
-XX:-PrintWarnings if the warning is causing trouble on VM output
stream.
The warning is also associated with an assert for our debug builds,
as we discussed privately.

>      bsd << os::is_interrupted >> posix
>        picked up a long comment from the Solaris version
>
> src/os/linux/vm/os_linux.cpp
>      Deletes os::sleep(), os::naked_sleep(), os::interrupt() and
>      os::is_interrupted().
>
>      linux << os::sleep >> posix
>        << assert(!Linux::supports_monotonic_clock(), "time moving
> backwards");
>        >> warning("time moving backwards");
>            The above diff happens twice. Without at least an assert here
>            we will be less likely to see this issue pop-up on specific
>            test machines.

Same comment as above.

>      linux << os::is_interrupted >> posix
>        picked up a long comment from the Solaris version
>
> src/os/solaris/vm/os_solaris.cpp
>      Deletes os::sleep(), os::naked_sleep(), os::interrupt() and
>      os::is_interrupted(). Also deletes static os_sleep() and
>      os::Solaris::setup_interruptible_already_blocked()
>
>      solaris << os::interrupt >> posix
>        << // When events are used everywhere for os::sleep, then this
> thr_kill
>        << // will only be needed if UseVMInterruptibleIO is true.
>        << if (!isInterrupted) {
>        <<   int status = thr_kill(osthread->thread_id(),
> os::Solaris::SIGinterrupt());
>        <<   assert_status(status == 0, status, "thr_kill");
>            Deleting the above code presumes that you're also going to
>            remove the remaining uses of UseVMInterruptibleIO. Should
>            that be done with this changeset so things are not out of
>            sync.

Initially I had the fix for 6546236 and the removal of
UseVMInterruptibleIO in the same workspace, but I split it into
two different changesets to ease tracking in our bug database.
The changeset to remove UseVMInterruptibleIO should be ready very
soon after fix for 6546236 has been pushed.

>        << // Bump thread interruption counter
>        << RuntimeService::record_thread_interrupt_signaled_count();
>            This call was only ever made on Solaris. Is this just a
>            counter for when a SIGinterrupt has to be thrown because
>            of the UseVMInterruptibleIO stuff?
>
>      Doesn't this deletion make INTERRUPTIBLE_NORESTART_VM_ALWAYS
>      unused so it can be deleted from
>      src/os/solaris/vm/os_solaris.inline.hpp
>
>      Were you also planning on removing the last vestiges of
>      UseVMInterruptibleIO? Or will that be done with another bug?

The changeset to remove UseVMInterruptibleIO includes all those cleanup:
clean deprecation of the flag, re-work of all the macros around
interruptible calls, cleanup of RuntimeServices methods and the
associated performance counters.

> src/os/posix/vm/os_posix.cpp
>      Adds os::sleep(), os::naked_sleep(), os::interrupt() and
>      os::is_interrupted().
>
>      > // the interrupted flag into the os::Solaris::Event structure,
>          Should this be more generic instead of "Solaris" specific?

I replaced this comment by the new version provided by David Holmes,
so no more Solaric specific content.

Thank you,

Fred

> On 2/10/14 8:58 AM, Frederic Parain wrote:
>> Greetings,
>>
>> Please review this fix for JDK-6546236.
>>
>> A race condition exists in the implementation of
>> Thread.sleep() and Thread.interrupt() on the
>> Solaris platform. For historical reasons, the
>> Solaris implementation of sleep() and interrupt()
>> differs from the other Unices (Linux, BSD).
>> It uses poll() calls while Linux and BSD are
>> using ParkEvents.
>>
>> This changeset reconciles the Solaris code with
>> Linux and BSD code. And instead of having three
>> copies of this code, sleep() and interrupt()
>> code are moved to the os_posix.cpp from
>> os_[solaris|linux|bsd].cpp files.
>>
>> Note that with this changeset, the Solaris
>> implementation of sleep() and interrupt()
>> is loosing the support for UseVMInterruptibleIO
>> but this is not an issue because this VM
>> flag has been deprecated in JDK8 and will be
>> removed in JDK9.
>>
>> The code has been tested with JPRT, vm.quick.testlist
>> as well as jdk_lang, jdk_util, jdk_nio and jdk_awt
>> (not a random list, all those jdk_* test suites are
>> using Thread.sleep() and thread.interrupt()).
>>
>> The bug description:
>> https://bugs.openjdk.java.net/browse/JDK-6546236
>>
>> The webrev:
>> http://cr.openjdk.java.net/~fparain/6546236/webrev.00/
>>
>> Thank you,
>>
>> Fred
>>
>

-- 
Frederic Parain - Oracle
Grenoble Engineering Center - France
Phone: +33 4 76 18 81 17
Email: Frederic.Parain at oracle.com