我在尝试调试的Perl(在Linux下)中的一个相当复杂的程序遇到问题。我可以使用以下简单代码段(test.pl
)模拟问题:
use warnings;
use strict;
use feature qw/say/;
my @testa = ();
my $numelems = 10000;
# populate array/list of arrays
for (my $ix = 0; $ix < $numelems; $ix++) {
my @miniarr = ($ix, 1);
push(@testa, \@miniarr);
}
say "Array is now " . scalar(@testa) . " elements long";
my $BADnumelems = $numelems + 2;
my $sum = 0;
# loop through array/list of arrays
for (my $ix = 0; $ix < $BADnumelems; $ix++) {
my @minientry = @{$testa[$ix]};
$sum += $minientry[0];
}
say "Sum of elements is $sum";
运行该程序将退出:
$ perl test.pl
Array is now 10000 elements long
Can't use an undefined value as an ARRAY reference at test.pl line 22.
所以,现在我想调试它-但该错误导致程序死亡,并退出调试器:
$ perl -d test.pl
Loading DB routines from perl5db.pl version 1.32
Editor support available.
Enter h or `h h' for help, or `man perldebug' for more help.
main::(test.pl:6): my @testa = ();
DB<1> c
Array is now 10000 elements long
Can't use an undefined value as an ARRAY reference at test.pl line 22.
at test.pl line 22
Debugged program terminated. Use q to quit or R to restart,
use o inhibit_exit to avoid stopping after program termination,
h q, h R or h o to get additional info.
DB<1> p $sum
DB<2> exit
$
然后,我发现break on warning in debugger (PerlMonks);所以我尝试添加以下内容:
...
use feature qw/say/;
$SIG{__DIE__} = sub { my($signal) = @_; say "DIEhandler: $signal"; $DB::single = 1; };
$SIG{__WARN__} = sub { my($signal) = @_; say "WARNhandler: $signal"; $DB::single = 1; };
my @testa = ();
...
...但是这也会杀死调试器:
$ perl -d test.pl
Loading DB routines from perl5db.pl version 1.32
Editor support available.
Enter h or `h h' for help, or `man perldebug' for more help.
main::(test.pl:6): $SIG{__DIE__} = sub { my($signal) = @_; say "DIEhandler: $signal"; $DB::single = 1; };
DB<1> c
Array is now 10000 elements long
DIEhandler: Can't use an undefined value as an ARRAY reference at test.pl line 25.
Can't use an undefined value as an ARRAY reference at test.pl line 25.
Debugged program terminated. Use q to quit or R to restart,
use o inhibit_exit to avoid stopping after program termination,
h q, h R or h o to get additional info.
现在,我知道如果我用Ctrl-C中断程序-通常会导致调试器进入步进模式;否则,调试器将进入 Debug模式。例如,您可以设置
my $numelems = 100000000;
,并在其循环时按Ctrl-C-并可以调试:$ perl -d test.pl
Loading DB routines from perl5db.pl version 1.32
Editor support available.
Enter h or `h h' for help, or `man perldebug' for more help.
main::(test.pl:6): $SIG{__DIE__} = sub { my($signal) = @_; say "DIEhandler: $signal"; $DB::single = 1; };
DB<1> c
^Cmain::(test.pl:14): my @miniarr = ($ix, 1);
DB<1> p $ix
148607
DB<2> q
现在,我可以insert break point into source perl program:
...
for (my $ix = 0; $ix < $BADnumelems; $ix++) {
$DB::single = 1; ### <=== BREAK HERE
my @minientry = @{$testa[$ix]};
...
但它在
$ix = 0
时进入循环:$ perl -d test.pl
Loading DB routines from perl5db.pl version 1.32
Editor support available.
Enter h or `h h' for help, or `man perldebug' for more help.
main::(test.pl:6): $SIG{__DIE__} = sub { my($signal) = @_; say "DIEhandler: $signal"; $DB::single = 1; };
DB<1> c
Array is now 10000 elements long
main::(test.pl:26): my @minientry = @{$testa[$ix]};
DB<1> p $ix
0
DB<2> q
...并且我不想单步执行10000个元素来了解有问题的部分
:)
因此,我认为以下内容-如果有一种方法可以从Perl脚本本身中引发/生成/创建SIGINT(Ctrl-C),那么我将能够从die处理程序中引发它,并希望在此过程中有所作为。进程终止之前的调试器。因此,我的问题是:
die
程序所在的调试器步进模式? 最佳答案
有了这些(尽管不确定我是否正确理解了:)
的所有内容),这要归功于这些:
只需使用
eval
包装和warn
修改代码,如下所示:...
# loop through array/list of arrays
for (my $ix = 0; $ix < $BADnumelems; $ix++) {
eval {
my @minientry;
@minientry = @{$testa[$ix]};
$sum += $minientry[0];
}; # just this causes step into debugger at $ix = 10001
warn $@ if $@; # this causes step into debugger at $ix=10000 (OK)
}
...
...然后调试器的工作方式如下:
$ perl -d test.pl
Loading DB routines from perl5db.pl version 1.32
Editor support available.
Enter h or `h h' for help, or `man perldebug' for more help.
main::(test.pl:6): $SIG{__DIE__} = sub { my($signal) = @_; say "DIEhandler: $signal"; @_ = (); $DB::single = 1; };
DB<1> c
Array is now 10000 elements long
DIEhandler: Can't use an undefined value as an ARRAY reference at test.pl line 27.
main::(test.pl:30): warn $@ if $@; # this causes step into debugger at $ix=10000 (OK)
DB<1> p $ix
10000
DB<2> p @{$testa[$ix]}
DB<3> p @{$testa[$ix-1]}
99991
DB<4> p join("--", @{$testa[$ix]})
DB<5> p join("--", @{$testa[$ix-1]})
9999--1
DB<6> q
...就是直接进入有问题的行,这就是我想要的。
好吧,希望这对某人有帮助,
干杯!
编辑:也可能相关:Why do I need to localize $@ before using eval?
关于perl - 从Perl脚本创建/引发SIGINT(Ctrl-C)-并导致从模具处理程序进入调试器进入步骤模式?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/14755634/