[prev in list] [next in list] [prev in thread] [next in thread] 

List:       openjdk-serviceability-dev
Subject:    Re: Call new Win32 API SetThreadDescription in os::set_native_thread_name
From:       David Holmes <david.holmes () oracle ! com>
Date:       2020-02-07 2:00:12
Message-ID: 51b20779-a6de-b9ce-08d5-8c155fd2a3f9 () oracle ! com
[Download RAW message or body]

Hi Markus,

Adding hotspot-runtime-dev as runtime owns this area of code.

On 7/02/2020 4:07 am, Gaisbauer, Markus wrote:
> Hi,
> 
> I am looking for a sponsor who could create a ticket for the following proposal:

Have you signed the OCA?

https://www.oracle.com/technetwork/community/oca-486395.html

I don't see you listed.

> Microsoft recently introduced a new API to assign a name to native Windows threads.
> https://docs.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-setthreaddescription
>  
> These thread names can be shown by debuggers, C++ profilers, etc. The new API is \
> available since either Windows 10 1607 or Windows Server 2016.

Thanks for that heads up about the new API. I have filed:

https://bugs.openjdk.java.net/browse/JDK-8238649

for that enhancement.

Thanks,
David
-----

> The JVM already tries to set a native thread name both for all internal JVM threads \
> and all Java threads (except main). 
> But the Windows implementation of os::set_native_thread_name currently uses a weird \
> hack described here. \
> https://docs.microsoft.com/en-us/visualstudio/debugger/how-to-set-a-thread-name-in-native-code?view=vs-2015&redirectedfrom=MSDN
>  
> For this hack, debugger has to be already attached when a thread starts.
> 
> I propose to check in os::set_native_thread_name if SetThreadDescription is \
> available. If yes, either call it instead or in addition to the current code. 
> Here is some prototype code that worked for me:
> 
> typedef HRESULT(WINAPI *SetThreadDescriptionT)(HANDLE, PCWSTR);
> 
> static SetThreadDescriptionT getSetThreadDescriptionT() {
> HMODULE kernel32 = GetModuleHandle("Kernel32.dll");
> return kernel32 ? reinterpret_cast<SetThreadDescriptionT>(GetProcAddress(kernel32, \
> "SetThreadDescription")) : nullptr; }
> 
> static LPWSTR utf8_decode(const char *name) {
> if (name == nullptr) return nullptr;
> int name_len = (int) strlen(name);
> int size_needed = MultiByteToWideChar(CP_UTF8, 0, name, name_len, NULL, 0);
> size_t buffer_len = sizeof(wchar_t) * (size_needed + 1);
> LPWSTR result = (LPWSTR) os::malloc(buffer_len, mtInternal);
> memset(result, 0, buffer_len);
> MultiByteToWideChar(CP_UTF8, 0, name, name_len, result, size_needed);
> return result;
> }
> 
> void os::set_native_thread_name(const char *name) {
> 
> // First try calling SetThreadDescription available since Windows 10 1607 / Windows \
> Server 2016 // See: \
> https://docs.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-setthreaddescription
>  
> static SetThreadDescriptionT SetThreadDescription = getSetThreadDescriptionT();
> if (SetThreadDescription) {
> LPWSTR nameWide = utf8_decode(name);
> if (nameWide != nullptr) {
> SetThreadDescription(GetCurrentThread(), nameWide);
> os::free(nameWide);
> }
> return;
> }
> 
> // fallback
> ...
> }
> 
> Best regards,
> Markus
> The contents of this e-mail are intended for the named addressee only. It contains \
> information that may be confidential. Unless you are the named addressee or an \
> authorized designee, you may not copy or use it, or disclose it to anyone else. If \
> you received it in error please notify us immediately and then destroy it. \
> Dynatrace Austria GmbH (registration number FN 91482h) is a company registered in \
> Linz whose registered office is at 4020 Linz, Austria, Am Fünfundzwanziger Turm 20 


[prev in list] [next in list] [prev in thread] [next in thread]