[jira] [Closed] (LOGCXX-554) Child thread does not inherit a copy of the mapped diagnostic context of its parent

["Robert Middleton (Jira)" <lo...@logging.apache.org>]

     [ https://issues.apache.org/jira/browse/LOGCXX-554?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Robert Middleton closed LOGCXX-554.
-----------------------------------
    Resolution: Won't Fix

Since this is not a feature that log4cxx has ever supported, and there is effectively no way to handle copying thread local data between threads in C++, closing as "won't fix."

> Child thread does not inherit a copy of the mapped diagnostic context of its parent
> -----------------------------------------------------------------------------------
>
>                 Key: LOGCXX-554
>                 URL: https://issues.apache.org/jira/browse/LOGCXX-554
>             Project: Log4cxx
>          Issue Type: Bug
>    Affects Versions: 0.12.1, 0.13.0
>         Environment: Linux - red hat 8.3/Windows 10/ Windows server 2016 64 bit
>            Reporter: Stefan Jipa
>            Priority: Major
>             Fix For: 0.13.0, 0.12.1
>
>
> Hi,
>  
> The API documentation for MDC says "The MDC is managed on a per thread basis. A child thread automatically inherits a copy of the mapped diagnostic context of its parent."
> However this does not appear to be the case. Take the following testcase:
> #include <iostream>
> #include <pthread.h>
> #include <log4cxx/mdc.h>
> using namespace std;
> void *threadfunc(void *arg)
> {
> std::cout << "child: " << log4cxx::MDC::get("mykey") << std::endl;
> }
> int main(int argc, char *argv[])
> {
> pthread_t thread_id;
> log4cxx::MDC::put("mykey", "123");
> std::cout << "main: " << log4cxx::MDC::get("mykey") << std::endl;
> pthread_create(&thread_id, NULL, threadfunc, NULL);
> pthread_join(thread_id, NULL);
> return 0;
> }
>  
> The resulted output is:
> main: 123
> child:
>  
> Instead of:
> main: 123
> child: 123
>  
> This simple program was executed on red hat 8.3 (used  c++17 and log4cxx 0.12.1)
> For compiling this simple program I used the following command line:
> g++ -std=c++17 -D_GLIBCXX_USE_CXX11_ABI=0 -I log4cxx_path/include -L log4cxx_path/lib/ -llog4cxx -L apr-util_path/lib/ -laprutil-1 -L apr_path/lib/ -lapr-1 -pthread -o test_mdc test_mdc.cpp
> This issue also happens on windows 64 bit in our applications (log4cxx 0.12.1) and I have found the same issue reported under this jira: LOGCXX-339 (and also is known on web as a latent problem)
> I checked the release notes of log4cxx 0.13.0 and it does not seem to address this issue and probably it was never fixed cause the resolution for the issue stated above was supposed to be fixed in the new versions.
>  
> Could you check this on the latest log4cxx (0.13.0)? and if is still happening please provide a solution.
>  
> Thanks,
> Stefan Jipa



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