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# Debug the c-code with gdb inspired by: https://dev.to/wataash/how-to-create-and-debug-ruby-gem-with-c-native-extension-3l8b ## install ruby with sources rbenv is your friend ;) 😄 -k means keep sources ``` rbenv install -k 2.6.3 rbenv shell 2.6.3 # check that ruby is debuggable type ruby # => ruby is /home/wsh/.rbenv/shims/ruby rbenv which ruby # => /home/wsh/.rbenv/versions/2.6.3/bin/ruby ``` ## ## add debug info when compiling appoptics_apm add this line to extconf.rb to turn off optimization ``` CONFIG["optflags"] = "-O0" ``` ## ## start ruby app with gdb This will run ruby and load the app with a breakpoint in the Reporter::startThread c-function. `bundle exec gdb -q -ex 'set breakpoint pending on' -ex 'b Reporter::startThread' -ex run --args ruby -e 'require "./app"'` If there is a bug in the ruby code or a ruby byebug binding that halts the script, the debugger will hang without showing any output. So, make sure `bundle exec ruby app.rb` runs. use the gdb navigation commands to step through the code. If it says: ``` (gdb) n Single stepping until exit from function _ZN8Reporter11startThreadEv@plt, which has no line number information. ``` type `c` and it may end up stopping in the right location. ## ## make ruby .gdbinit macros available These macros are pretty elaborate. They are checked in the ruby github repo: https://github.com/ruby/ruby/blob/master/.gdbinit The code is nicely formatted and colorized in github and easiest to read there. installation in the user's home dir: ``` wget https://github.com/ruby/ruby/blob/master/.gdbinit ``` ## ## examples Some inspiring examples here: https://jvns.ca/blog/2016/06/12/a-weird-system-call-process-vm-readv/ https://medium.com/@zanker/finding-a-ruby-bug-with-gdb-56d6b321bc86
Version data entries
10 entries across 10 versions & 1 rubygems