###############################################################
# system-limits.PL
#
# probe the limitations of this system including the maximum
# number of simultaneous child processes and the maximum number
# of open filehandles.
#
# this information is used in t/32-stress-test.t and to create
# the Forks/Super/SysInfo.pm file
#
# v0.77: use a second limits file to store capabilities that
# probably do not depend on your version of perl. Read from
# this file so that SysInfo.pm.PL will run faster the
# second time (if say, you install Forks::Super for different
# versions of perl on your system).
# [see https://rt.cpan.org/Public/Bug/Display.html?id=105454]
#
###############################################################
use lib q(lib);
use strict;
use warnings;
use Config;
use POSIX;
our $VERSION = '0.89';
my $limits_file = $ARGV[0] || "t/out/limits.$^O.$]";
my $limits2 = $ARGV[1] || "t/out/limits.$^O";
my %LIMITS;
if (-f $limits2) {
open my $fh, '<', $limits2;
while (<$fh>) {
s/\s+$//;
my ($key,$val) = split /:/, $_, 2;
$LIMITS{'sys|' . $key} = $val;
}
close $fh;
unless ($LIMITS{'sys|valid'}) {
%LIMITS = ();
}
}
$LIMITS{file} = $limits_file;
$LIMITS{sysfile} = $limits2;
our $MAIN_PID = $$;
my $pid = 0;
if ($^O eq 'MSWin32') {
if ("@ARGV" !~ / --bg /) {
$pid = system 1, "$^X $0 @ARGV --bg";
}
} elsif ($INC{'perl5db.pl'}) {
$pid = 0;
} else {
$pid = fork;
}
if ($pid) {
print $pid;
for (my $i = 0; $i < 5; $i++) {
if (! -r $limits_file) {
sleep 1;
}
}
print STDERR "\n\n";
if (! -r $limits_file) {
warn "System limitations file $limits_file still not found.\n ";
}
if ($^O eq 'cygwin') {
# clean up the stray process with the same PGID as this process.
# If that works, it will suppress the "WSFO time out ..." error.
my $target_pgid = $$;
if (fork() == 0) {
$0="system-limits.PL cygwin cleanup";
sleep 30;
my @proc_table = qx(/usr/bin/ps);
shift @proc_table; # skip header
foreach my $ps (@proc_table) {
next if $ps =~ m(/usr/bin/ps);
$ps =~ s/^\s+//;
my @ps = split /\s+/, $ps;
if ($ps[2] == $target_pgid && $ps[0] != $target_pgid) {
sleep 10;
system("taskkill /f /pid $ps[3]");
}
}
exit;
}
}
exit;
}
unless ($INC{'perl5db.pl'}) {
close $_ for *STDOUT, *STDERR, *STDIN;
if ($ENV{QQQUIET}) {
open TTY, $^O eq 'MSWin32' ? '>nul' : '>/dev/null';
} else {
open TTY, $^O eq 'MSWin32' ? '>con' : '>/dev/tty';
}
*STDOUT = *STDERR = *TTY;
}
# for best results, only one process should be testing limits at a time
open(LOCK, ">>", "t/out/.lock-flim");
flock LOCK, 2;
END {
if ($$ == $MAIN_PID) {
close LOCK;
unlink "t/out/.lock-flim";
}
}
$LIMITS{system} = $^O;
$LIMITS{version} = $];
write_limits();
# XXX - what else is interesting?
# max pending signals?
&get_Time_HiRes_tolerance;
&count_number_of_cpus;
&find_max_open_filehandles; # on some systems: ulimit -n
&find_max_open_sockets; # TODO
&find_socket_capacity;
&find_pipe_capacity; # on some systems: 512 * ulimit -p
&wait_waitpid_results;
&explore_sync_options;
&explore_alternate_alarm;
&check_proc_process_table;
# gnukfreebsd/midnightbsd can see "Maximal count of pending signals
# (120) exceeded" messages in t/32.
&find_max_fork(
$^O eq 'gnukfreebsd' || $^O eq 'midnighbsd' ? 110 : 300
); # run last because it might crash the program
print "Created system limitations file in: $limits_file in ",time-$^T,"s\n";
close LOCK;
#############################################################################
sub write_limits {
my (%new_data) = @_;
$LIMITS{$_}=$new_data{$_} for keys %new_data;
my @l2 = ();
open(my $lhf, '>', $LIMITS{file});
while (my ($key,$val) = each %LIMITS) {
if ($key =~ s/^sys\|//) {
push @l2, "$key:$val\n";
}
print $lhf "$key:$val\n";
}
close $lhf;
if (@l2 && $limits2) {
open my $lh2, '>', $limits2;
print $lh2 @l2;
close $lh2;
}
}
#############################################################################
sub get_Time_HiRes_tolerance {
# I found an insidious bug where this code:
# do {
# $t1 = Time::HiRes::time();
# $t2 = Time::HiRes::time();
# $t2 < $t1
# };
# could return *TRUE*!
#
# On opensolaris 5.11 (running on Oracle VM Virtualbox, which was
# running on Windows 7), this can be as much as 0.03s.
#
# Even on Windows 7/Cygwin, it can be 0.0005s
#
# www.cpantesters.org/cpan/report/df00514e-153d-11e1-b03e-8398e1de4735:
# this value is 0.89s ?!?!?!
#
# Ideally, this subroutine is run on a lightly loaded system.
return if defined $LIMITS{'sys|TimeHiRes_tol'};
unless (eval 'use Time::HiRes (); 1') {
write_limits(TimeHiRes_tol => '0E0');
}
my ($max,$t,$u,$diff) = (0, Time::HiRes::time());
my $v = $t + 10;
while ($t < $v) {
($u,$t) = ($t,Time::HiRes::time());
$diff = $u-$t;
$max=$diff if $max<$diff;
}
if ($max > 0) {
print STDOUT "Observed time on this system skipping backwards by ${max}s.\n";
} else {
print STDOUT "No timing anomalies observed on this system.\n";
}
write_limits('sys|TimeHiRes_tol' => $max * 1.1);
}
# sub checkif_sleep_alarm_compatible
# wasn't deemed as reliable as moving this check
# directly into SysInfo.pm.PL
#
# determine the maximum number of simultaneous background processes
#
sub find_max_fork {
return if $LIMITS{'sys|maxfork'};
my $N = shift;
my $limits_file = $LIMITS{file};
if (-f $limits_file) {
unlink $limits_file;
}
print "";
undef $@;
my $r = eval {
unlink "$limits_file.pid";
for (my $i=1; $i<=$N; $i++) {
undef $@;
my $pid;
eval { $pid = fork() }; # CORE::fork, not Forks::Super::fork
if ($@ || !defined $pid) {
print "Cannot fork more than $i child processes.\n";
1 while wait > -1;
exit 0;
} elsif ($pid == 0) {
print "";
$0 = "system-limits.PL \&find_max_fork";
sleep 10;
exit 0;
}
if ($i > 1) {
&write_limits('sys|maxfork' => $i, 'sys|valid' => 1);
}
}
1 while wait > -1;
if ($N < 2000) {
print "$^O-$] successfully forked $N processes.\n";
return find_max_fork(2000);
}
print "$^O-$] successfully forked $N processes.\n";
$N;
};
print "Result: ",defined($r)?$r:'<undef>'," / $@\n";
return $r;
}
#
# determine the maximum number of open filehandles allowed
# by a process on this system. The module doesn't (currently)
# do anything with this information.
#
sub find_max_open_filehandles {
# in BSD, this information can be obtained from
# sysctl kern.maxfiles[=new_value]
# sysctl kern.maxfilesperproc[=new_value]
# in Linux, check out the files. They can be written to.
# /proc/sys/kernel|fs/file-max [max open filehandles]
# /proc/sys/kernel/inode-max
# /proc/sys/kernel/file-nr [filehandles in use]
# Per process limits from: ulimit -n ; sudo ulimit -n <n>
# Solaris: add to /etc/system:
# set rlim_fd_max = xxxx
# set rlim_fd_cur = xxxx
# we also want to get the error number for the
# "Too many open files" and "No such file or directory"
# error messages -- in a different locale we cannot
# count on $! containing any particular text.
my $i = 0;
undef $!;
my $j = $$;
my @fh = ();
while (open (my $fh, ">", "xxx.$j")) {
$i++;
push @fh, $fh;
}
my $err = 0 + $!;
close $_ for @fh;
# print "Msg for $i open files: $err\n";
$! = $err;
&write_limits('maxfilehandle' => $i,
'maxfilehandle_msg' => $!,
'maxfilehandle_errno' => $err);
unlink "xxx.$j";
print "Can open $i file handles simultaneously\n";
#################################
# also figure out the errno
# for file not found.
#################################
$! = 0;
open my $xh, '<', 'qwpor/qwer/qw/t/346/234/t';
&write_limits('fnf_errno' => 0+$!,
'fnf_msg' => $!);
return $i;
}
sub find_max_open_sockets {
# TODO
}
# what values do CORE::wait and CORE::waitpid return
# for bogus inputs? What are the side effects on $? ?
sub wait_waitpid_results {
use POSIX ':sys_wait_h';
my %info = ();
my $pid = CORE::fork();
if (defined($pid) && $pid==0) {
$0 = "system-limits.PL wait_waitpid_results";
sleep 3;
exit;
}
$info{active_waitpid_result} = waitpid $pid, &WNOHANG;
$info{active_waitpid_status} = $?;
# XXX - not idiot proof - $pid+1 could be a valid process identifier
$info{bogus_waitpid_result} = waitpid $pid+1, &WNOHANG;
$info{bogus_waitpid_status} = $?;
waitpid $pid, 0;
$info{reaped_waitpid_result} = waitpid $pid, &WNOHANG;
$info{reaped_waitpid_status} = $?;
local $SIG{CHLD} = 'IGNORE';
$pid = CORE::fork();
exit if $pid == 0;
sleep 1;
$info{ignore_waitpid_result} = waitpid $pid, 0;
$info{ignore_waitpid_status} = $?;
if ($info{ignore_waitpid_result} == $pid) {
$info{ignore_waitpid_result} = 'undef';
$info{ignore_waitpid_status} = 'undef';
}
write_limits( %info );
}
#
# what options are available to this system for interprocess synchronization?
#
sub explore_sync_options {
my @sync = ();
@_ = ();
if ($^O eq 'MSWin32' || $^O =~ /cygwin/i) {
if (eval { require Win32::Semaphore; 1 }) {
print "Win32 semaphores are available for ",
"ipc synchronization\n";
push @sync, "Win32";
write_limits( sync_options => join('/', @sync) );
}
if (eval { require Win32::Mutex; 1 }) {
print "Win32 mutexes are available for ",
"ipc synchronization\n";
push @sync, "Win32Mutex";
write_limits( sync_options => join('/', @sync) );
}
}
if (eval {
# exercise IPC::Semaphore
no warnings 'prototype','redefine';
require IPC::SysV;
require IPC::Semaphore;
IPC::SysV->import(qw(IPC_PRIVATE S_IRUSR S_IWUSR IPC_CREAT IPC_NOWAIT));
my $sem = IPC::Semaphore->new(&IPC_PRIVATE, 2,
&S_IRUSR | &S_IWUSR | &IPC_CREAT);
$sem->setall(1,0);
$sem->setval(1,1);
$sem->remove;
eval { alarm 0 };
1
} ) {
print "SysV semaphores are available for ipc synchronization\n";
push @sync, "IPCSemaphore";
write_limits( sync_options => join('/', @sync) );
}
# advisory file locking ? It actually might not work so well on
# Cygwin, or with NFS filesystems, and it could be slower than
# the other methods. So make this the last option.
my $file = "foo.$$";
if (fork() == 0) {
open my $fh, ">>", $file;
flock $fh, 2;
sleep 5;
close $fh;
exit;
}
sleep 2;
open my $fh, '>>', $file;
my $t = time;
eval { eval { alarm 30 }; flock $fh, 2; alarm 0; };
$t = time - $t;
close $fh;
if ($t > 1 && $t < 20) {
print "advisory filelocking available for ipc synchronization\n";
push @sync, "Semaphlock";
write_limits( sync_options => join('/', @sync) );
}
unlink $file;
write_limits( sync_options => join('/', @sync) );
}
sub signame_to_signum {
use Config;
my $sig = shift;
my @signames = split ' ',$Config{sig_name};
my @signums = split ' ',$Config{sig_num};
for my $i (0 .. $#signames) {
if ($signames[$i] eq $sig) {
return $signums[$i];
}
}
return $sig;
}
# usual method of making a child process timeout in Forks::Super
# is to use `alarm`. Occasionally (I'm looking at you, freebsd)
# this is not a good option, and we have to resort to the
# poor man's alarm (see &poor_mans_alarm in Forks/Super/Job/OS.pm).
#
# If you get test failures for t/40g-timeout.t and t/65e-daemon.t,
# this is a good place to start.
#
# more investigation needed, but it looks like the alternate
# alarm is needed for systems where SIGALRM cannot interrupt
# a system call in a grandchild process
#
# RT#118730 - maybe MacOS/darwin should use the alt alarm
sub explore_alternate_alarm {
if (defined $ENV{PREFER_ALT_ALARM}) {
write_limits( prefer_alt_alarm => $ENV{PREFER_ALT_ALARM}+0 );
} elsif ($^O =~ /bsd|darwin/) {
write_limits( prefer_alt_alarm => 1 );
} else {
write_limits( prefer_alt_alarm => 0 );
}
return;
}
# There exist systems where Proc::ProcessTable is installed
# but it segfaults anyway.
sub check_proc_process_table {
my $pid = fork;
if ($pid == 0) {
require Proc::ProcessTable;
Proc::ProcessTable->new->table;
exit 0;
}
waitpid $pid, 0;
if ($?) {
write_limits( proc_processtable_ok => 0 );
} else {
write_limits( proc_processtable_ok => 1 );
}
}
#
# try to guess how many processors this system has.
# Eventually we could use that information to set
# a default value of $Forks::Super::MAX_PROC in the
# installed code.
#
# See also: Sys::CpuAffinity getNumCpus() method
# Forks::Super::Job::OS::get_number_of_processors() method
#
sub count_number_of_cpus {
my ($ncpu, $fh);
return if $LIMITS{'sys|ncpu'};
$ncpu = 0;
my $sys = 0;
if (eval "require Sys::CpuAffinity; 1") {
$ncpu = Sys::CpuAffinity::getNumCpus();
# darwin: result might have format "1 [2 cores]"
$ncpu =~ s{\d+ \[(\d+) cores\]}{$1};
$sys = !!$ncpu;
}
if ($ncpu == 0 && eval "require Test::Smoke::SysInfo;1") {
my $sysinfo = Test::Smoke::SysInfo->new();
$ncpu = $sysinfo && $sysinfo->{_ncpu};
$sys = !!$ncpu;
}
if ($ncpu == 0 && $^O eq "MSWin32") {
$ncpu = $ENV{NUMBER_OF_PROCESSORS};
$sys = !$ncpu;
}
if ($ncpu == 0 && open($fh,'<','/proc/cpuinfo')) {
$ncpu = grep /^processor\s/, <$fh>;
close $fh;
$sys = !!$ncpu;
}
if ($ncpu == 0 && open($fh,'<','/proc/stat')) {
$ncpu = grep /^cpu\d/i, <$fh>;
close $fh;
$sys = !!$ncpu;
}
if ($ncpu == 0) {
$ncpu = grep /\d+.+processors?$/i, qx(hinv -c processor 2>/dev/null);
$sys =!!$ncpu;
}
if ($ncpu == 0) {
$ncpu = () = qx(bindprocessor -q 2>/dev/null);
$sys =!!$ncpu;
}
if ($ncpu == 0) {
$ncpu = grep /^hw.ncpu:/, qx(sysctl -a 2>/dev/null);
$sys =!!$ncpu;
}
if ($ncpu == 0) {
$ncpu = () = qx(psrinfo 2> /dev/null);
$sys =!!$ncpu;
}
if ($ncpu == 0) {
$ncpu = qx(hwprefs cpu_count 2>/dev/null);
$sys =!!$ncpu;
}
if ($ncpu && $ncpu > 0) {
print "There are $ncpu cpus on this system.\n";
if ($sys) {
write_limits( 'sys|ncpu' => $ncpu + 0 );
} else {
write_limits( ncpu => $ncpu + 0 );
}
} else {
print "I am having trouble detecting the number\n";
print "of processors on your system. Consider\n";
print "installing the Sys::CpuAffinity module\n";
print "before running this script.\n";
write_limits( ncpu => "1.0" );
}
}
sub find_socket_capacity {
return if $LIMITS{'sys|socket_capacity'};
my $socket_capacity =
_get_capacity(16384, 1,
qq[use Socket;
socketpair DUMMY,WRITER,AF_UNIX,SOCK_STREAM,PF_UNSPEC]);
print "Default socket capacity is about $socket_capacity bytes\n";
&write_limits('sys|socket_capacity' => $socket_capacity);
close DUMMY;
close WRITER;
}
sub find_pipe_capacity {
return if $LIMITS{'sys|pipe_capacity'};
my $pipe_capacity =
_get_capacity(256, 2, qq[pipe DUMMY,WRITER]);
print "Default pipe capacity is about $pipe_capacity bytes\n";
&write_limits('sys|pipe_capacity' => $pipe_capacity);
close DUMMY;
close WRITER;
}
sub _get_capacity {
my ($packetsize, $timeout, $create_WRITER) = @_;
my $capacity = __get_capacity($packetsize,$timeout,$create_WRITER);
while ($capacity <= 0) {
if ($capacity > -2) {
return 0 if $packetsize <= 1;
print "Packet size of $packetsize was too large. Retrying\n";
$packetsize = int($packetsize / 64);
} elsif ($capacity == -2) {
return 0 if $timeout > 300;
print "Capacity not found with timeout=$timeout. Retrying\n";
$timeout *= 2;
}
$capacity = __get_capacity($packetsize,$timeout,$create_WRITER);
}
return $capacity;
}
#####################################################################
# to find the capacity of a pipe or socket on this system,
# the idea is to keep writing bytes to the handle until it blocks.
# Windows is pretty cantankerous and it is hard to recover from the
# deadlock when a write operation blocks: the 4-arg select won't
# work with pipes (and it doesn't work that well with sockets,
# anyway), and alarm() won't interrupt an I/O operation.
# The portable solution is overkill on non-Windows systems but
# gets the job done -- test the socket in a separate process
# (NOT a psuedo-process/thread) and let the process kill itself
# when it times out.
#####################################################################
sub __get_capacity {
my ($packetsize, $timeout, $create_WRITER, $output_file) = @_;
$output_file ||= "./test-capacity.out";
my $pid_file = "./test-capacity.pid";
if ($packetsize < 1) {
$packetsize = 1;
}
# capacity == -1 means the packetsize was too large: decrease packetsize
# capacity == -2 means the pipe did not block: increase timeout
my $capacity = -1;
my $code = <<"__END_SLAVE_CODE__";
use IO::Handle;
use strict;
\$| = 1;
$create_WRITER;
*WRITER->autoflush(1);
binmode WRITER;
my \$output = " " x $packetsize;
my \$written = 0;
for (;;) {
# print WRITER \$output;
syswrite WRITER, \$output;
\$written += length \$output;
open F, ">", \"$output_file\";
print F time - \$^T >= $timeout ? -2 : \$written;
close F;
}
__END_SLAVE_CODE__
;
unlink $output_file, $pid_file;
if (fork() == 0) {
$0 = "system-limits.PL __get_capacity";
sleep $timeout + 1;
open my $pf, '<', $pid_file;
my $pid = 0 + <$pf>;
# hopefully, one of these will do the job on your system
kill ('TERM', $pid)
|| kill ('HUP', $pid)
|| !system ("TASKKILL /f /pid $pid")
|| do {
warn "Attempts to kill pid \"$pid\" failing ...\n"; 0
}
|| !system ("kill -TERM $pid")
|| kill ('BREAK', $pid);
exit 0;
}
my $pid = open(SLAVE, "| $^X");
open my $pf, '>', $pid_file;
print $pf $pid;
close $pf;
print SLAVE $code;
close SLAVE;
sleep 1;
open(CAP, '<', $output_file);
$capacity = (<CAP>)[-1];
close CAP;
unlink $output_file, $pid_file;
return $capacity + 0;
}
__END__
RT#105454 - speed up system-limits.PL, especially when it
is run for a second time (say, for a different version of perl):
some information is system-specific, not perl specific.
Perhaps we could store some information in a more general
t/out/limits.$^O file:
ncpu
maxfork
system
RT#118474 - report that all tests about timeouts fail on darwin.
Would darwin benefit from the "alternate alarm" that we
started using on bsd?