RFR: 8183925: Decouple crash protection from watcher thread

[Robbin Ehn]

On 07/07/2017 05:43 AM, Daniel D. Daugherty wrote:
> On 7/6/17 4:33 AM, Robbin Ehn wrote:
>> Hi all, please review:
>>
>> While looking into:
>> java_lang_Thread::get_thread_status(oop java_thread) {
>>      4802:   assert(Thread::current()->is_Watcher_thread()
>> As: http://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2017-July/023863.html
>>
>> I saw that I have missed that crash protection doesn't work for the upcoming trace backend changes.
>> Main reason for not seeing this is that the trace backend haven't crashed (yet).
>>
>> This code is not used in the open-jdk, compiled tested linux and windows.
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8183925
>> Webrev: http://cr.openjdk.java.net/~rehn/8183925/webrev/index.html
> 
> General comments
>    - Please update copyright years as needed before pushing.

done

> 
> src/os/posix/vm/os_posix.hpp
>      No comments.
> 
> src/os/posix/vm/os_posix.cpp
>      L1306:   assert(_protected_thread != NULL, "Cannot crash protect a none Thread");
>          Typo: 'none Thread' -> 'NULL thread'
> 

done

> src/os/windows/vm/os_windows.hpp
>      No comments.
> 
> src/os/windows/vm/os_windows.cpp
>      L4842:   assert(_protected_thread != NULL, "Cannot crash protect a none Thread");
>          Typo: 'none Thread' -> 'NULL thread'
> 

done

>      Really don't like the variable named 'success', but that
>      pre-dates these changes.
> 
> src/os_cpu/bsd_x86/vm/os_bsd_x86.cpp
> src/os_cpu/linux_aarch64/vm/os_linux_aarch64.cpp
> src/os_cpu/linux_arm/vm/os_linux_arm.cpp
> src/os_cpu/linux_s390/vm/os_linux_s390.cpp
> src/os_cpu/linux_sparc/vm/os_linux_sparc.cpp
> src/os_cpu/linux_x86/vm/os_linux_x86.cpp
> src/os_cpu/solaris_sparc/vm/os_solaris_sparc.cpp
> src/os_cpu/solaris_x86/vm/os_solaris_x86.cpp
>      Same change to this set of files; no comments.
> 
> src/share/vm/runtime/mutex.cpp
>      L1392: assert(!os::ThreadCrashProtection::is_crash_protected(thread),
>      L1393:            "locking not allowed when crash protection is set");
>          nit - two extra spaces before '"' on L1393.

done

> 
> src/share/vm/runtime/os.cpp
>      L576:   // checking for the WatcherThread and crash_protection first
>      L579:   // try to find the thread after we see that the watcher thread
>          These comments mention "WatcherThread" and "watcher thread"
>          so they need to be updated.

done

> 
>      L582:          "Can't malloc with crash protection from WatcherThread");
>          "from WatcherThread" should be "from crash protected thread"
>          or something similar.
> 
>          Or you could do something like the mutex.cpp mesg:
> 
>          "locking not allowed when crash protection is set"
>          "malloc() not allowed when crash protection is set"

done

> 
> src/share/vm/runtime/thread.hpp
>      No comments.
> 
> src/share/vm/runtime/thread.cpp
>      No comments.
> 
> 
> Thumbs up! I don't need to see another webrev if you make
> the above minor changes...

Thanks you Dan!

/Robbin

> 
> Dan
> 
> 
>>
>> Thanks!
>>
>> /Robbin
>