RFR: 8036128 Remove deprecated VM flag UseVMInterruptibleIO

Karen Kinnear karen.kinnear at oracle.com
Fri Mar 7 19:02:35 UTC 2014


This looks great. And thank you so much.

Questions for you:

1. os::read
Yes we need to clean this up. Thank you for pointing that out.
I am concerned that if we skip state transitions when making OS calls that can block, that
we can possibly increase pause times trying to get to a safepoint, or possibly interfere with
requests for thread suspension. I updated 6523731 to include this in our cleaning up our
thread state transitions.

2. os::connect
The change to RESTARTABLE confuses me. I expected to see the current two step handling
in case of an EINTR (see 6343810 - at the very end it describes why this is Solaris-specific).
Or are you removing that because this will only be used internally and in debug mode and not
from the JDK soon?

3. jstat
I didn't see this in your tested list - and I believe that the way this works is dynamic, so you are probably
ok, but - since you removed perfcounters 
- what happens if your ~/.jvmstat/jstat_options was referencing this data?
and you run jstat -options and then try to dump these options?

David - I asked Frederic to put this flag in the obsolete_jvm_flags - that is our current deprecation mechanism -
i.e. for all the flags we are deprecating in JDK9, they should have obsoleted_in: 9, accept_until: 10. So the mechanism isn't
obsolete - it triggers a warning mechanism. We can rename it and rework it to not mention HSX, but we still
need to deprecate product flags even without HSX. Can we remove really old entries? Yes. Should we keep flags in there
that reference JDK9? I would prefer to keep those in for JDK9, so the information gets printed for customers about
when the flag became obsolete.


On Mar 6, 2014, at 11:40 PM, David Holmes wrote:

> Hi Fred,
> This looks good to me! Great to see the cleanup happen.
> os_solaris.cpp:
> This comment block seems redundant now:
> 5264       /*
> 5265       * XXX: is the following call interruptible? If so, this might
> 5266       * need to go through the INTERRUPT_IO() wrapper as for other
> 5267       * blocking, interruptible calls in this file.
> 5268       */
> ---
> Aside: arguments.cpp - I guess we can file an RFE to get rid of obsolete_jvm_flags now that hsx is dead. ;-)
> Cheers,
> David
> On 7/03/2014 2:12 AM, frederic parain wrote:
>> Greetings,
>> The UseVMInterruptibleIO flag removal has been
>> scheduled a long time ago:
>> https://bugs.openjdk.java.net/browse/JDK-4385444
>> Now, it's time to effectively remove this flag and
>> its associated code.
>> Removing this feature includes removing all the
>> macros used to deal with interruptible I/Os, which
>> could make the reading of the webrev hard and painful.
>> I conservatively preserved the asserts that were
>> inserted by the INTERRUPTIBLE macros, with one
>> notable exception for os::read(). The original
>> asserts checked that the current ThreadState
>> was not _thread_in_native nor _thread_blocked.
>> I changed it into an assert checking that the
>> current thread state is _thread_in_vm. The
>> rational for that is that the only real usage
>> of os::read() on Solaris is in the
>> ClassPathDirEntry::open_stream() method, which
>> is always called with ThreadState ==_thread_in_vm.
>> This change makes the TreadStateTransition simpler
>> and avoid having to store the previous ThreadState.
>> This choice could be revisited once the rules
>> for ThreadStateTransition around system calls
>> when ThreadState is _thread_in_vm are clarified
>> (Solaris is currently the only platform doing
>> this kind of transition for os::read()).
>> The CR:
>> https://bugs.openjdk.java.net/browse/JDK-8036128
>> The webrev:
>> http://cr.openjdk.java.net/~fparain/8036128/webrev.00/
>> Tested with vm.quick.testlist and JPRT hotspot job.
>> Thanks,
>> Fred

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