diff options
Diffstat (limited to 'contrib/perl5/pod/perldebguts.pod')
| -rw-r--r-- | contrib/perl5/pod/perldebguts.pod | 48 |
1 files changed, 25 insertions, 23 deletions
diff --git a/contrib/perl5/pod/perldebguts.pod b/contrib/perl5/pod/perldebguts.pod index b74f3ef..20cc546 100644 --- a/contrib/perl5/pod/perldebguts.pod +++ b/contrib/perl5/pod/perldebguts.pod @@ -13,17 +13,17 @@ intimate with Perl's guts to understand. Caveat lector. Perl has special debugging hooks at compile-time and run-time used to create debugging environments. These hooks are not to be confused -with the I<perl -Dxxx> command described in L<perlrun>, which are -usable only if a special Perl built per the instructions the +with the I<perl -Dxxx> command described in L<perlrun>, which is +usable only if a special Perl is built per the instructions in the F<INSTALL> podpage in the Perl source tree. For example, whenever you call Perl's built-in C<caller> function from the package DB, the arguments that the corresponding stack -frame was called with are copied to the the @DB::args array. The +frame was called with are copied to the @DB::args array. The general mechanisms is enabled by calling Perl with the B<-d> switch, the following additional features are enabled (cf. L<perlvar/$^P>): -=over +=over 4 =item * @@ -32,20 +32,22 @@ Perl inserts the contents of C<$ENV{PERL5DB}> (or C<BEGIN {require =item * -The array C<@{"_<$filename"}> holds the lines of $filename for all -files compiled by Perl. The same for C<eval>ed strings that contain +Each array C<@{"_<$filename"}> holds the lines of $filename for a +file compiled by Perl. The same for C<eval>ed strings that contain subroutines, or which are currently being executed. The $filename for C<eval>ed strings looks like C<(eval 34)>. Code assertions -in regexes look like C<(re_eval 19)>. +in regexes look like C<(re_eval 19)>. + +Values in this array are magical in numeric context: they compare +equal to zero only if the line is not breakable. =item * -The hash C<%{"_<$filename"}> contains breakpoints and actions keyed +Each hash C<%{"_<$filename"}> contains breakpoints and actions keyed by line number. Individual entries (as opposed to the whole hash) are settable. Perl only cares about Boolean true here, although the values used by F<perl5db.pl> have the form -C<"$break_condition\0$action">. Values in this hash are magical -in numeric context: they are zeros if the line is not breakable. +C<"$break_condition\0$action">. The same holds for evaluated strings that contain subroutines, or which are currently being executed. The $filename for C<eval>ed strings @@ -53,7 +55,7 @@ looks like C<(eval 34)> or C<(re_eval 19)>. =item * -The scalar C<${"_<$filename"}> contains C<"_<$filename">. This is +Each scalar C<${"_<$filename"}> contains C<"_<$filename">. This is also the case for evaluated strings that contain subroutines, or which are currently being executed. The $filename for C<eval>ed strings looks like C<(eval 34)> or C<(re_eval 19)>. @@ -154,7 +156,7 @@ L<perldebug/"Options"> for description of options parsed by C<DB::parse_options(string)>. The function C<DB::dump_trace(skip[, count])> skips the specified number of frames and returns a list containing information about the calling frames (all of them, if -C<count> is missing). Each entry is reference to a a hash with +C<count> is missing). Each entry is reference to a hash with keys C<context> (either C<.>, C<$>, or C<@>), C<sub> (subroutine name, or info about C<eval>), C<args> (C<undef> or a reference to an array), C<file>, and C<line>. @@ -400,7 +402,7 @@ shorter than 7 chars. The fields of interest which may appear in the last line are -=over +=over 4 =item C<anchored> I<STRING> C<at> I<POS> @@ -630,7 +632,7 @@ Perl is a profligate wastrel when it comes to memory use. There is a saying that to estimate memory usage of Perl, assume a reasonable algorithm for memory allocation, multiply that estimate by 10, and while you still may miss the mark, at least you won't be quite so -astonished. This is not absolutely true, but may prvide a good +astonished. This is not absolutely true, but may provide a good grasp of what happens. Assume that an integer cannot take less than 20 bytes of memory, a @@ -639,7 +641,7 @@ than 32 bytes (all these examples assume 32-bit architectures, the result are quite a bit worse on 64-bit architectures). If a variable is accessed in two of three different ways (which require an integer, a float, or a string), the memory footprint may increase yet another -20 bytes. A sloppy malloc(3) implementation can make inflate these +20 bytes. A sloppy malloc(3) implementation can inflate these numbers dramatically. On the opposite end of the scale, a declaration like @@ -666,7 +668,7 @@ the top level of the Perl source tree. If your perl is using Perl's malloc() and was compiled with the necessary switches (this is the default), then it will print memory -usage statistics after compiling your code hwen C<< $ENV{PERL_DEBUG_MSTATS} +usage statistics after compiling your code when C<< $ENV{PERL_DEBUG_MSTATS} > 1 >>, and before termination of the program when C<< $ENV{PERL_DEBUG_MSTATS} >= 1 >>. The report format is similar to the following example: @@ -686,12 +688,12 @@ the following example: Total sbrk(): 215040/47:145. Odd ends: pad+heads+chain+tail: 0+2192+0+6144. It is possible to ask for such a statistic at arbitrary points in -your execution using the mstats() function out of the standard +your execution using the mstat() function out of the standard Devel::Peek module. Here is some explanation of that format: -=over +=over 4 =item C<buckets SMALLEST(APPROX)..GREATEST(APPROX)> @@ -720,7 +722,7 @@ of two--or possibly one page greater. In the second row, if present, the memory footprints of the buckets are between the memory footprints of two buckets "above". -For example, suppose under the pervious example, the memory footprints +For example, suppose under the previous example, the memory footprints were free: 8 16 32 64 128 256 512 1024 2048 4096 8192 @@ -804,7 +806,7 @@ To see this list, insert two C<warn('!...')> statements around the call: do 'lib/auto/POSIX/autosplit.ix'; warn('!!! "after"'); -and run it with PErl's B<-DL> option. The first warn() will print +and run it with Perl's B<-DL> option. The first warn() will print memory allocation info before parsing the file and will memorize the statistics at this point (we ignore what it prints). The second warn() prints increments with respect to these memorized data. This @@ -838,11 +840,11 @@ per glob - for glob name, and glob stringification magic. Here are explanations for other I<Id>s above: -=over +=over 4 =item C<717> -CReates bigger C<XPV*> structures. In the case above, it +Creates bigger C<XPV*> structures. In the case above, it creates 3 C<AV>s per subroutine, one for a list of lexical variable names, one for a scratchpad (which contains lexical variables and C<targets>), and one for the array of scratchpads needed for @@ -892,7 +894,7 @@ these categories. If warn() string starts with -=over +=over 4 =item C<!!!> |
