RFR (S): 8149901: [Solaris] Use of -XX:+UseThreadPriorities crashes fastdebug

[David Holmes]

Ping - need a Reviewer please.

David

On 18/05/2016 6:21 AM, David Holmes wrote:
> On 18/05/2016 12:49 AM, Gerard Ziemski wrote:
>> Looks good.
>
> Thanks.
>
> Can I get a Reviewer as well please.
>
> David
> -----
>
>>
>> thanks
>>
>>> On May 16, 2016, at 4:03 PM, David Holmes <david.holmes at oracle.com>
>>> wrote:
>>>
>>> Hi Gerard,
>>>
>>> Thanks for looking at this.
>>>
>>> On 17/05/2016 1:19 AM, Gerard Ziemski wrote:
>>>> hi David,
>>>>
>>>> The fix seems reasonable, but the following comment seems to be
>>>> missing the end of its last sentence?
>>>>
>>>> +  // Most thread types will set an explicit priority before
>>>> starting the thread,
>>>> +  // but for those that don't we need a valid value to read back in
>>>> thread_native_entry.
>>>
>>> This is the complete comment.
>>>
>>>> +  // Push a default initial priority into the osThread to be read
>>>> back when the new
>>>
>>> This line is deleted. I forgot to refresh the webrev - now done.
>>>
>>> Thanks,
>>> David
>>>
>>>> +  osthread->set_native_priority(NormPriority);
>>>> +
>>>>
>>>>
>>>> cheers
>>>>
>>>>> On May 16, 2016, at 12:47 AM, David Holmes
>>>>> <david.holmes at oracle.com> wrote:
>>>>>
>>>>> bug: https://bugs.openjdk.java.net/browse/JDK-8149901
>>>>>
>>>>> webrev: http://cr.openjdk.java.net/~dholmes/8149901/webrev/
>>>>>
>>>>> JDK-8038473 removed the old code pertaining to use of the T1
>>>>> threads library and related unused flags - like
>>>>> DefaultThreadPriority. One chunk of code it removed from
>>>>> os::create_thread was:
>>>>>
>>>>> // Set the default thread priority. If using bound threads, setting
>>>>> // lwp priority will be delayed until thread start.
>>>>> set_native_priority(thread, DefaultThreadPriority == -1 ?
>>>>>                             java_to_os_priority[NormPriority] :
>>>>>                             DefaultThreadPriority);
>>>>>
>>>>> but by removing this, the logic in thread_native_entry (formerly
>>>>> java_start) would read back an uninitialized field from the
>>>>> OSThread instance for any thread type (eg VMThread) which did not
>>>>> explicitly set the priority before calling os::start_thread - and
>>>>> that would cause a range check assertion to fire.
>>>>>
>>>>> The simple fix, because we only deal with bound threads (and so we
>>>>> know we will skip most of os::set_native_priority) is to just push
>>>>> a default priority into the OSThread instance directly:
>>>>>
>>>>> osthread->set_native_priority(NormPriority);
>>>>>
>>>>> Ideally I would have fixed this in the OSThread constructor but it
>>>>> is shared code and knows nothing about the native_priority field on
>>>>> Solaris.
>>>>>
>>>>> I found a number of related issues when looking closely at this
>>>>> code, and have filed:
>>>>>
>>>>> https://bugs.openjdk.java.net/browse/JDK-8157010
>>>>>
>>>>> as a followup cleanup for Java 10.
>>>>>
>>>>> Thanks,
>>>>> David
>>>>
>>