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MDEV-28931 MTR prints detailed stack trace unconditionally 
66832e3 introduced change that prints core dumps in very detailed
format. That's completely out of user-friendliness but serves as a
measure for debugging hard-reproducible bugs.

The proper way to implement this:

  1. it must be controlled by command-line and environment variable;
  2. detailed traces must be default for buildbots only, for user
     invocations normal stack traces should be printed.

Options for control are: MTR_PRINT_CORE and --print-core that accept
the following values:

  no	         Don't print core
  short	       	 Print stack trace of failed thread
  medium	 Print stack traces of all threads
  detailed       Print all stack traces with debug context
  custom:<code>  Use debugger commands <code> to print stack trace

Default setting is: short (see env_or_default() call in pre_setup())

For environment variable wrong values are silently ignored (falls back
to default setting, see env_or_default()).

Command-line option --print-core (or -C) overrides environment
variable. Its default value is 'short' if not specified explicitly
(same env_or_default() call in pre_setup()). Explicit values are
checked for validity.

--print-method option can specify by which debugger we print
cores. For Windows there is only one choice: cdb. For Unix the values
are: gdb, dbx, lldb, auto. Default value is: auto

In 'auto' we try to use all possible debuggers until success.
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@midenok
midenok committed Jul 18, 2022
1 parent 220fb67 commit e9be542
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Showing 2 changed files with 209 additions and 35 deletions.
237 mysql-test/lib/My/CoreDump.pm
View file
@@ -19,9 +19,141 @@ package My::CoreDump;
use strict;
use Carp;
use My::Platform;
use Text::Wrap;
use Data::Dumper;

use File::Temp qw/ tempfile tempdir /;
use mtr_results;
use mtr_report;

my %opts;
my %config;
my $help = "\n\nOptions for printing core dumps\n\n";

sub register_opt($$$) {
my ($name, $format, $msg)= @_;
my @names= split(/\|/, $name);
my $option_name= $names[0];
$option_name=~ s/-/_/;
$opts{$name. $format}= \$config{$option_name};
$help.= wrap(sprintf(" %-23s", join(', ', @names)), ' 'x25, "$msg\n");
}

# To preserve order we use array instead of hash
my @print_formats= (
short => {
description => "Failing stack trace",
codes => {}
},
medium => {
description => "All stack traces",
codes => {}
},
detailed => {
description => "All stack traces with debug context",
codes => {}
},
custom => {
description => "Custom debugger script for printing stack"
},
# 'no' must be last (check generated help)
no => {
description => "Skip stack trace printing"
}
);

# TODO: make class for each {method, get_code}
my @print_methods= (IS_WINDOWS) ? (cdb => { method => \&_cdb }) : (
gdb => {
method => \&_gdb,
get_code => \&_gdb_format,
},
dbx => {
method => \&_dbx
},
lldb => {
method => \&_lldb
},
# 'auto' must be last (check generated help)
auto => {
method => \&_auto
}
);

# But we also use hash
my %print_formats= @print_formats;
my %print_methods= @print_methods;

# and scalar
my $x= 0;
my $print_formats= join(', ', grep { ++$x % 2 } @print_formats);
$x= 0;
my $print_methods= join(', ', grep { ++$x % 2 } @print_methods);

# Fill 'short' and 'detailed' formats per each print_method
# that has interface for that
for my $f (keys %print_formats)
{
next unless exists $print_formats{$f}->{codes};
for my $m (keys %print_methods)
{
next unless exists $print_methods{$m}->{get_code};
# That calls f.ex. _gdb_format('short')
# and assigns { gdb => value-of-_gdb_format } into $print_formats{short}->{format}:
$print_formats{$f}->{codes}->{$m}= $print_methods{$m}->{get_code}->($f);
}
}

register_opt('print-core|C', ':s',
"Print core dump format: ". $print_formats. " (for not printing cores). ".
"Defaults to value of MTR_PRINT_CORE or 'short'");
if (!IS_WINDOWS)
{
register_opt('print-method', '=s',
"Print core method: ". join(', ', $print_methods). " (try each method until success). ".
"Defaults to 'auto'");
}

sub options() { %opts }
sub help() { $help }


sub env_or_default($$) {
my ($default, $env)= @_;
if (exists $ENV{$env}) {
my $f= $ENV{$env};
$f= 'custom'
if $f =~ m/^custom:/;
return $ENV{$env}
if exists $print_formats{$f};
mtr_verbose("$env value ignored: $ENV{$env}");
}
return $default;
}

sub pre_setup() {
$config{print_core}= env_or_default('short', 'MTR_PRINT_CORE')
if not defined $config{print_core};
$config{print_method}= (IS_WINDOWS) ? 'cdb' : 'auto'
if not defined $config{print_method};
# If the user has specified 'custom' we fill appropriate print_format
# and that will be used automatically
# Note: this can assign 'custom' to method 'auto'.
if ($config{print_core} =~ m/^custom:(.+)$/) {
$config{print_core}= 'custom';
$print_formats{'custom'}= {
$config{print_method} => $1
}
}
mtr_error "Wrong value for --print-core: $config{print_core}"
if not exists $print_formats{$config{print_core}};
mtr_error "Wrong value for --print-method: $config{print_method}"
if not exists $print_methods{$config{print_method}};

mtr_debug(Data::Dumper->Dump(
[\%config, \%print_formats, \%print_methods],
[qw(config print_formats print_methods)]));
}

my $hint_mysqld; # Last resort guess for executable path

@@ -50,8 +182,38 @@ sub _verify_binpath {
return $binpath;
}


# Returns GDB code according to specified format

# Note: this is like simple hash, separate interface was made
# in advance for implementing below TODO

# TODO: _gdb_format() and _gdb() should be separate class
# (like the other printing methods)

sub _gdb_format($) {
my ($format)= @_;
my %formats= (
short => "bt\n",
medium => "thread apply all bt\n",
detailed =>
"bt\n".
"set print sevenbit on\n".
"set print static-members off\n".
"set print frame-arguments all\n".
"thread apply all bt full\n".
"quit\n"
);
confess "Unknown format: ". $format
unless exists $formats{$format};
return $formats{$format};
}


sub _gdb {
my ($core_name)= @_;
my ($core_name, $code)= @_;
confess "Undefined format"
unless defined $code;

# Check that gdb exists
`gdb --version`;
@@ -61,7 +223,7 @@ sub _gdb {
}

if (-f $core_name) {
print "\nTrying 'gdb' to get a backtrace from coredump $core_name\n";
mtr_verbose("Trying 'gdb' to get a backtrace from coredump $core_name");
} else {
print "\nCoredump $core_name does not exist, cannot run 'gdb'\n";
return;
@@ -76,13 +238,7 @@ sub _gdb {

# Create tempfile containing gdb commands
my ($tmp, $tmp_name) = tempfile();
print $tmp
"bt\n",
"set print sevenbit on\n",
"set print static-members off\n",
"set print frame-arguments all\n",
"thread apply all bt full\n",
"quit\n";
print $tmp $code;
close $tmp or die "Error closing $tmp_name: $!";

# Run gdb
@@ -105,7 +261,7 @@ EOF


sub _dbx {
my ($core_name)= @_;
my ($core_name, $format)= @_;

print "\nTrying 'dbx' to get a backtrace\n";

@@ -167,7 +323,7 @@ sub cdb_check {


sub _cdb {
my ($core_name)= @_;
my ($core_name, $format)= @_;
print "\nTrying 'cdb' to get a backtrace\n";
return unless -f $core_name;

@@ -304,32 +460,47 @@ EOF
}


sub _auto
{
my ($core_name, $code, $rest)= @_;
# We use ordered array @print_methods and omit auto itself
my @valid_methods= @print_methods[0 .. $#print_methods - 2];
my $x= 0;
my @methods= grep { ++$x % 2} @valid_methods;
my $f= $config{print_core};
foreach my $m (@methods)
{
my $debugger= $print_methods{$m};
confess "Broken @print_methods"
if $debugger->{method} == \&_auto;
# If we didn't find format for 'auto' (that is only possible for 'custom')
# we get format for specific debugger
if (not defined $code && defined $print_formats{$f} and
exists $print_formats{$f}->{codes}->{$m})
{
$code= $print_formats{$f}->{codes}->{$m};
}
mtr_verbose2("Trying to print with method ${m}:${f}");
if ($debugger->{method}->($core_name, $code)) {
return;
}
}
}


sub show {
my ($class, $core_name, $exe_mysqld, $parallel)= @_;
$hint_mysqld= $exe_mysqld;

# On Windows, rely on cdb to be there...
if (IS_WINDOWS)
{
_cdb($core_name);
return;
}

my @debuggers =
(
\&_gdb,
\&_dbx,
\&_lldb,
# TODO...
);

# Try debuggers until one succeeds

foreach my $debugger (@debuggers){
if ($debugger->($core_name)){
return;
if ($config{print_core} ne 'no') {
my $f= $config{print_core};
my $m= $config{print_method};
my $code= undef;
if (exists $print_formats{$f}->{codes} and
exists $print_formats{$f}->{codes}->{$m}) {
$code= $print_formats{$f}->{codes}->{$m};
}
mtr_verbose2("Printing core with method ${m}:${f}");
mtr_debug("code: ${code}");
$print_methods{$m}->{method}->($core_name, $code);
}
return;
}
7 mysql-test/mysql-test-run.pl
View file
@@ -1346,7 +1346,8 @@ sub command_line_setup {
'skip-test-list=s' => \@opt_skip_test_list,
'xml-report=s' => \$opt_xml_report,

My::Debugger::options()
My::Debugger::options(),
My::CoreDump::options()
);

# fix options (that take an optional argument and *only* after = sign
@@ -1761,6 +1762,8 @@ sub command_line_setup {
$opt_debug= 1;
$debug_d= "d,query,info,error,enter,exit";
}

My::CoreDump::pre_setup();
}


@@ -5764,7 +5767,7 @@ ($)

local $"= ','; # for @DEFAULT_SUITES below

print <<HERE . My::Debugger::help() . <<HERE;
print <<HERE . My::Debugger::help() . My::CoreDump::help() . <<HERE;
$0 [ OPTIONS ] [ TESTCASE ]

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