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docs: lwsws under gdb / valgrind from ml

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Andy Green 2017-08-27 09:50:04 +08:00
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README.lwsws.md
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@ -576,3 +576,26 @@ Prepare the log directory like this
sudo mkdir /var/log/lwsws sudo mkdir /var/log/lwsws
sudo chmod 700 /var/log/lwsws sudo chmod 700 /var/log/lwsws
``` ```
@section lwswsgdb Debugging lwsws with gdb
Hopefully you won't need to debug lwsws itself, but you may want to debug your plugins. start lwsws like this to have everything running under gdb
```
sudo gdb -ex "set follow-fork-mode child" -ex "run" --args /usr/local/bin/lwsws
```
this will give nice backtraces in lwsws itself and in plugins, if they were built with symbols.
@section lwswsvgd Running lwsws under valgrind
You can just run lwsws under galgrind as usual and get valid results. However the results / analysis part of valgrind runs
after the plugins have removed themselves, this means valgrind backtraces into plugin code is opaque, without
source-level info because the dynamic library is gone.
There's a simple workaround, use LD_PRELOAD=<plugin.so> before running lwsws, this has the loader bring the plugin
in before executing lwsws as if it was a direct dependency. That means it's still mapped until the whole process
exits after valgtind has done its thing.