RFR: JDK-8152690: main thread does not have native thread name

[Robbin Ehn]

FYI: I'm not a Reviewer.

/Robbin

On 03/30/2016 10:55 PM, Robbin Ehn wrote:
> Thanks, looks good.
>
> /Robbin
>
> On 03/30/2016 03:47 PM, Yasumasa Suenaga wrote:
>> Hi,
>>
>> I uploaded new webrev.
>> Could you review it?
>>
>>    http://cr.openjdk.java.net/~ysuenaga/JDK-8152690/webrev.01/
>>
>>
>> Thanks,
>>
>> Yasumasa
>>
>>
>> On 2016/03/30 19:10, Robbin Ehn wrote:
>>> Hi,
>>>
>>> On 03/30/2016 11:41 AM, Yasumasa Suenaga wrote:
>>>> Hi Robbin,
>>>>
>>>> 2016/03/30 18:22 "Robbin Ehn" <robbin.ehn at oracle.com
>>>> <mailto:robbin.ehn at oracle.com>>:
>>>>  >
>>>>  > Hi Yasumasa,
>>>>  >
>>>>  >
>>>>  > On 03/25/2016 12:48 AM, Yasumasa Suenaga wrote:
>>>>  >>
>>>>  >> Hi Robbin,
>>>>  >> 2016/03/25 1:51 "Robbin Ehn" <robbin.ehn at oracle.com
>>>> <mailto:robbin.ehn at oracle.com>
>>>>  >> <mailto:robbin.ehn at oracle.com <mailto:robbin.ehn at oracle.com>>>:
>>>>  >>
>>>>  >>  >
>>>>  >>  > Hi Yasumasa,
>>>>  >>  >
>>>>  >>  > I'm not sure why you don't set it:
>>>>  >>  >
>>>>  >>  > diff -r ded6ef79c770 src/share/vm/runtime/thread.cpp
>>>>  >>  > --- a/src/share/vm/runtime/thread.cpp   Thu Mar 24 13:09:16 2016
>>>> +0000
>>>>  >>  > +++ b/src/share/vm/runtime/thread.cpp   Thu Mar 24 17:40:09 2016
>>>> +0100
>>>>  >>  > @@ -3584,6 +3584,7 @@
>>>>  >>  >    JavaThread* main_thread = new JavaThread();
>>>>  >>  >    main_thread->set_thread_state(_thread_in_vm);
>>>>  >>  >    main_thread->initialize_thread_current();
>>>>  >>  > +  main_thread->set_native_thread_name("main");
>>>>  >>  >    // must do this before set_active_handles
>>>>  >>  >    main_thread->record_stack_base_and_size();
>>>>  >>  >
>>>> main_thread->set_active_handles(JNIHandleBlock::allocate_block());
>>>>  >>  >
>>>>  >>  > here instead? Am I missing something?
>>>>  >>
>>>>  >> Native thread name is the same to thread name in Thread class.
>>>>  >> It is set in c'tor in Thread or setName().
>>>>  >> If you create new thread in Java app, native thread name will be
>>>> set at
>>>>  >> startup. However, main thread is already starte in VM.
>>>>  >> Thread name for "main" is set in create_initial_thread().
>>>>  >> I think that the place of setting thrrad name should be the same.
>>>>  >
>>>>  >
>>>>  > Yes, I see your point. But then something like this is nicer, no?
>>>>  >
>>>>  > --- a/src/share/vm/runtime/thread.cpp   Tue Mar 29 09:43:05 2016
>>>> +0200
>>>>  > +++ b/src/share/vm/runtime/thread.cpp   Wed Mar 30 10:51:12 2016
>>>> +0200
>>>>  > @@ -981,6 +981,7 @@
>>>>  >  // Creates the initial Thread
>>>>  >  static oop create_initial_thread(Handle thread_group, JavaThread*
>>>> thread,
>>>>  >                                   TRAPS) {
>>>>  > +  static const char* initial_thread_name = "main";
>>>>  >    Klass* k =
>>>> SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true,
>>>> CHECK_NULL);
>>>>  >    instanceKlassHandle klass (THREAD, k);
>>>>  >    instanceHandle thread_oop =
>>>> klass->allocate_instance_handle(CHECK_NULL);
>>>>  > @@ -988,8 +989,10 @@
>>>>  >    java_lang_Thread::set_thread(thread_oop(), thread);
>>>>  >    java_lang_Thread::set_priority(thread_oop(), NormPriority);
>>>>  >    thread->set_threadObj(thread_oop());
>>>>  > -
>>>>  > -  Handle string = java_lang_String::create_from_str("main",
>>>> CHECK_NULL);
>>>>  > +
>>>>  > +  thread->set_native_thread_name(initial_thread_name);
>>>>  > +
>>>>  > +  Handle string =
>>>> java_lang_String::create_from_str(initial_thread_name, CHECK_NULL);
>>>>  >
>>>>  >    JavaValue result(T_VOID);
>>>>  >    JavaCalls::call_special(&result, thread_oop,
>>>>
>>>> Okay, I will upload new webrev later.
>>>
>>> Thanks!
>>>
>>>>
>>>>  >>  > The launcher seem to name itself 'java' and naming this thread
>>>> just
>>>>  >>  > 'main' is confusing to me.
>>>>  >>  >
>>>>  >>  > E.g. so main thread of the process (and thus the process) is
>>>> 'java' but
>>>>  >>  > first JavaThread is 'main'.
>>>>  >>
>>>>  >> The native main thread in the process is not JavaThread. It is
>>>> waiting
>>>>  >> for ending of Java main thread with pthread_join().
>>>>  >> set_native_thread_name() is for JavaThread. So I think that we do
>>>> not
>>>>  >> need to call it for native main thread.
>>>>  >
>>>>  >
>>>>  > Not sure if we can change it anyhow, since we want java and native
>>>> name to be the same and java thread name might have some dependents.
>>>>  >
>>>>  > The name is visible in e.g. /proc.
>>>>  >
>>>>  > $ ps H -C java -o 'pid tid comm' | head -4
>>>>  >   PID   TID COMMAND
>>>>  >  6423  6423 java
>>>>  >  6423  6424 main
>>>>  >  6423  6425 GC Thread#0
>>>>  >
>>>>  > It would be nice with something like 'Java Main Thread'.
>>>>
>>>> I do not think so.
>>>> Native main thread might not be a Java launcher - e.g. Apache
>>>> commons-daemon, JNI application, etc.
>>>>
>>>> If you want to change native main thread name, I think that we have to
>>>> change Java launcher code.
>>>> Should I include it in new webrev?
>>>
>>> No
>>>
>>> Thanks again!
>>>
>>> /Robbin
>>>
>>>>
>>>> Thanks,
>>>>
>>>> Yasumasa
>>>>
>>>>  > Thanks
>>>>  >
>>>>  > /Robbin
>>>>  >
>>>>  >
>>>>  >>
>>>>  >> Thanks,
>>>>  >>
>>>>  >> Yasumasa
>>>>  >>
>>>>  >>  > Thanks!
>>>>  >>  >
>>>>  >>  > /Robbin
>>>>  >>  >
>>>>  >>  > On 03/24/2016 03:26 PM, Yasumasa Suenaga wrote:
>>>>  >>  > > Hi all,
>>>>  >>  > >
>>>>  >>  > > HotSpot for Linux will set thread name via
>>>> pthread_setname_np().
>>>>  >>  > > However, main thread does not have it.
>>>>  >>  > >
>>>>  >>  > > All JavaThread have native name, and main thread is
>>>> JavaThread.
>>>>  >>  > > For consistency, main thread should have native thread name.
>>>>  >>  > >
>>>>  >>  > > I uploaded a webrev. Could you review it?
>>>>  >>  > >
>>>>  >>  > > http://cr.openjdk.java.net/~ysuenaga/JDK-8152690/webrev.00/
>>>>  >>  > >
>>>>  >>  > > I cannot access JPRT.
>>>>  >>  > > So I need a sponsor.
>>>>  >>  > >
>>>>  >>  > >
>>>>  >>  > > Thanks,
>>>>  >>  > >
>>>>  >>  > > Yasumasa
>>>>  >>  > >
>>>>  >>
>>>>