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