Hi Ben. Before you get too far into the details of using threads, can I ask why you're considering it? The memory footprint and performance of using forked processes with Perl is generally going to be better than that of threads, due to copy-on-write.
- Perrin On Mon, Apr 4, 2016 at 4:44 PM, Ben RUBSON <ben.rub...@gmail.com> wrote: > Hello, > > I have some questions regarding mod_perl, threads, thread-safe functions, > special vars scope... > > From > https://perl.apache.org/docs/2.0/user/coding/coding.html#toc_Thread_environment_Issues > : > "if you chdir() in one thread, all other thread now see the current > working directory of that thread that chdir()'ed to that directory" > Do we speak about threads from threaded MPM ? > (so the specific Apache process which owns the thread running this Perl > script, and all its (the process) threads, will chdir()). > > From the same page : > "Other usually problematic (non thread-safe) functions include readdir(), > srand(), etc." > Why readdir() would not be thread-safe ? I can't see why. Perhaps > readdir() chdir() to read a directory content ? > How could we then read dir content being thread-safe ? > > From > https://perl.apache.org/docs/general/perl_reference/perl_reference.html#toc_The_Scope_of_the_Special_Perl_Variables > : > "In the mod_perl situation where the child server doesn't usually exit, if > in one of your scripts you modify a global variable it will be changed for > the rest of the process' life and will affect all the scripts executed by > the same process." > So in a threaded MPM, if one of the threads modifies one of the special > Perl variables, it will instantly affect all other threads of this process ? > > What about variables like $? ? (return code of system() calls) > And ${^CHILD_ERROR_NATIVE} ? (return code too) > Does their value stay local to the thread ? / Does each thread have these > variables with their own proper value ? > Or is it unsafe to read them because they could be modified by another > thread ? > > Thank you very much for your clarification, > > Best regards, > > Ben > >
