From 2246621422759550fcf70a80236044b5a2747af7 Mon Sep 17 00:00:00 2001 From: Nils Dijk Date: Fri, 27 Oct 2023 16:57:51 +0200 Subject: [PATCH] automatically add a breakpoint that breaks on postgres errors (#7279) When debugging postgres it is quite hard to get to the source for `errfinish` in `elog.c`. Instead of relying on the developer to set a breakpoint in the `elog.c` file for `errfinish` for `elevel == ERROR`, this change adds the breakpoint to `.gdbinit`. This makes sure that whenever a debugger is attached to a postgres backend it will break on postgres errors. When attaching the debugger a small banner is printed that explains how to disable the breakpoint. --- .devcontainer/.gdbinit | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/.devcontainer/.gdbinit b/.devcontainer/.gdbinit index 9c710923fa6..9d544512b8f 100644 --- a/.devcontainer/.gdbinit +++ b/.devcontainer/.gdbinit @@ -3,3 +3,31 @@ # actually also works when debugging with vscode. Providing nice tools # to understand the internal datastructures we are working with. source /root/gdbpg.py + +# when debugging postgres it is convenient to _always_ have a breakpoint +# trigger when an error is logged. Because .gdbinit is sourced before gdb +# is fully attached and has the sources loaded. To make sure the breakpoint +# is added when the library is loaded we temporary set the breakpoint pending +# to on. After we have added out breakpoint we revert back to the default +# configuration for breakpoint pending. +# The breakpoint is hard to read, but at entry of the function we don't have +# the level loaded in elevel. Instead we hardcode the location where the +# level of the current error is stored. Also gdb doesn't understand the +# ERROR symbol so we hardcode this to the value of ERROR. It is very unlikely +# this value will ever change in postgres, but if it does we might need to +# find a way to conditionally load the correct breakpoint. +set breakpoint pending on +break elog.c:errfinish if errordata[errordata_stack_depth].elevel == 21 +set breakpoint pending auto + +echo \n +echo ----------------------------------------------------------------------------------\n +echo when attaching to a postgres backend a breakpoint will be set on elog.c:errfinish \n +echo it will only break on errors being raised in postgres \n +echo \n +echo to disable this breakpoint from vscode run `-exec disable 1` in the debug console \n +echo this assumes it's the first breakpoint loaded as it is loaded from .gdbinit \n +echo this can be verified with `-exec info break`, enabling can be done with \n +echo `-exec enable 1` \n +echo ----------------------------------------------------------------------------------\n +echo \n