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From: Eric Wong <e@80x24.org>
To: meta@public-inbox.org
Subject: [PATCH 09/22] ipc: wq: support dynamic worker count change
Date: Sun, 10 Jan 2021 12:15:06 +0000	[thread overview]
Message-ID: <20210110121519.17044-10-e@80x24.org> (raw)
In-Reply-To: <20210110121519.17044-1-e@80x24.org>

Increasing/decreasing workers count will be useful in
some situations.
---
 lib/PublicInbox/IPC.pm | 99 ++++++++++++++++++++++++++++++------------
 t/ipc.t                |  9 ++++
 2 files changed, 81 insertions(+), 27 deletions(-)

diff --git a/lib/PublicInbox/IPC.pm b/lib/PublicInbox/IPC.pm
index 0c5205c1..5bca3627 100644
--- a/lib/PublicInbox/IPC.pm
+++ b/lib/PublicInbox/IPC.pm
@@ -8,7 +8,7 @@ use v5.10.1;
 use Carp qw(confess croak);
 use PublicInbox::DS qw(dwaitpid);
 use PublicInbox::Spawn;
-use POSIX ();
+use POSIX qw(WNOHANG);
 use Socket qw(AF_UNIX MSG_EOR);
 my $SEQPACKET = eval { Socket::SOCK_SEQPACKET() }; # portable enough?
 use constant PIPE_BUF => $^O eq 'linux' ? 4096 : POSIX::_POSIX_PIPE_BUF();
@@ -112,7 +112,7 @@ sub ipc_worker_spawn {
 		$w_res->autoflush(1);
 		$SIG{$_} = 'IGNORE' for (qw(TERM INT QUIT));
 		local $0 = $ident;
-		PublicInbox::DS::sig_setmask($oldset);
+		PublicInbox::DS::sig_setmask($sigset);
 		my $on_destroy = $self->ipc_atfork_child;
 		eval { ipc_worker_loop($self, $r_req, $w_res) };
 		die "worker $ident PID:$$ died: $@\n" if $@;
@@ -229,12 +229,13 @@ sub ipc_sibling_atfork_child {
 	$pid == $$ and die "BUG: $$ ipc_atfork_child called on itself";
 }
 
-sub wq_worker_loop ($$) {
-	my ($self, $s2) = @_;
+sub wq_worker_loop ($) {
+	my ($self) = @_;
 	my $buf;
 	my $len = $self->{wq_req_len} // (4096 * 33);
 	my ($rec, $sub, @args);
-	while (1) {
+	my $s2 = $self->{-wq_s2} // die 'BUG: no -wq_s2';
+	until ($self->{-wq_quit}) {
 		my (@fds) = $recv_cmd->($s2, $buf, $len) or return; # EOF
 		my $i = 0;
 		my @m = @{$self->{wq_open_modes} // [qw( +<&= >&= >&= )]};
@@ -258,7 +259,7 @@ sub wq_worker_loop ($$) {
 
 sub wq_do { # always async
 	my ($self, $sub, $in, $out, $err, @args) = @_;
-	if (my $s1 = $self->{-wq_seq}) { # run in worker
+	if (my $s1 = $self->{-wq_s1}) { # run in worker
 		$_ = fileno($_) for ($in, $out, $err);
 		$send_cmd->($s1, $in, $out, $err,
 				freeze([$sub, @args]), MSG_EOR);
@@ -270,42 +271,86 @@ sub wq_do { # always async
 	}
 }
 
+sub _wq_worker_start ($$) {
+	my ($self, $oldset) = @_;
+	my $pid = fork // die "fork: $!";
+	if ($pid == 0) {
+		eval { PublicInbox::DS->Reset };
+		close(delete $self->{-wq_s1});
+		delete $self->{qw(-wq_workers -wq_quit)};
+		my $quit = sub { $self->{-wq_quit} = 1 };
+		$SIG{$_} = $quit for (qw(TERM INT QUIT));
+		$SIG{$_} = 'IGNORE' for (qw(TTOU TTIN));
+		local $0 = $self->{-wq_ident};
+		PublicInbox::DS::sig_setmask($oldset);
+		my $on_destroy = $self->ipc_atfork_child;
+		eval { wq_worker_loop($self) };
+		die "worker $self->{-wq_ident} PID:$$ died: $@\n" if $@;
+		exit;
+	} else {
+		$self->{-wq_workers}->{$pid} = \undef;
+	}
+}
+
 # starts workqueue workers if Sereal or Storable is installed
 sub wq_workers_start {
 	my ($self, $ident, $nr_workers, $oldset) = @_;
 	($enc && $send_cmd && $recv_cmd && defined($SEQPACKET)) or return;
-	return if $self->{-wq_seq}; # idempotent
+	return if $self->{-wq_s1}; # idempotent
 	my ($s1, $s2);
 	socketpair($s1, $s2, AF_UNIX, $SEQPACKET, 0) or die "socketpair: $!";
-	my $sigset = $oldset // PublicInbox::DS::block_signals();
 	$self->ipc_atfork_parent;
 	$nr_workers //= 4;
+	my $sigset = $oldset // PublicInbox::DS::block_signals();
 	$self->{-wq_workers} = {};
-	for my $i (0..($nr_workers - 1)) {
-		defined(my $pid = fork) or die "fork: $!";
-		if ($pid == 0) {
-			eval { PublicInbox::DS->Reset };
-			$s1 = undef;
-			$SIG{$_} = 'IGNORE' for (qw(TERM INT QUIT));
-			local $0 = $ident."[$i]";
-			PublicInbox::DS::sig_setmask($oldset);
-			my $on_destroy = $self->ipc_atfork_child;
-			eval { wq_worker_loop($self, $s2) };
-			die "worker $ident PID:$$ died: $@\n" if $@;
-			exit;
-		} else {
-			$self->{-wq_workers}->{$pid} = $i;
-		}
-	}
+	$self->{-wq_ident} = $ident;
+	$self->{-wq_s1} = $s1;
+	$self->{-wq_s2} = $s2;
+	_wq_worker_start($self, $sigset) for (1..$nr_workers);
 	PublicInbox::DS::sig_setmask($sigset) unless $oldset;
-	$s2 = undef;
-	$self->{-wq_seq} = $s1;
 	$self->{-wq_ppid} = $$;
 }
 
+sub wq_worker_incr { # SIGTTIN handler
+	my ($self, $oldset) = @_;
+	$self->{-wq_s2} or return;
+	$self->ipc_atfork_parent;
+	my $sigset = $oldset // PublicInbox::DS::block_signals();
+	_wq_worker_start($self, $sigset);
+	PublicInbox::DS::sig_setmask($sigset) unless $oldset;
+}
+
+sub wq_exit { # wakes up wq_worker_decr_wait
+	send($_[0]->{-wq_s2}, $$, MSG_EOR) // die "$$ send: $!";
+	exit;
+}
+
+sub wq_worker_decr { # SIGTTOU handler, kills first idle worker
+	my ($self) = @_;
+	my $workers = $self->{-wq_workers} or return;
+	my $s2 = $self->{-wq_s2} // die 'BUG: no wq_s2';
+	$self->wq_do('wq_exit', $s2, $s2, $s2);
+	$self->{-wq_exit_pending}++;
+	# caller must call wq_worker_decr_wait in main loop
+}
+
+sub wq_worker_decr_wait {
+	my ($self, $timeout) = @_;
+	return if $self->{-wq_ppid} != $$; # can't reap siblings or parents
+	my $s1 = $self->{-wq_s1} // croak 'BUG: no wq_s1';
+	vec(my $rin = '', fileno($s1), 1) = 1;
+	select(my $rout = $rin, undef, undef, $timeout) or
+		croak 'timed out waiting for wq_exit';
+	recv($s1, my $pid, 64, 0) // croak "recv: $!";
+	my $workers = $self->{-wq_workers} // croak 'BUG: no wq_workers';
+	delete $workers->{$pid} // croak "BUG: PID:$pid invalid";
+	$self->{-wq_exit_pending}--;
+	dwaitpid($pid, \&ipc_worker_reap, $self);
+}
+
 sub wq_close {
 	my ($self) = @_;
-	delete $self->{-wq_seq} or return;
+	delete @$self{qw(-wq_s1 -wq_s2)} or return;
 	my $ppid = delete $self->{-wq_ppid} // die 'BUG: no wq_ppid';
 	my $workers = delete $self->{-wq_workers} // die 'BUG: no wq_workers';
 	return if $ppid != $$; # can't reap siblings or parents
diff --git a/t/ipc.t b/t/ipc.t
index f09f76ef..51e347c6 100644
--- a/t/ipc.t
+++ b/t/ipc.t
@@ -168,4 +168,13 @@ like($warn[0], qr/ wq_do: /, '1st warned from wq_do');
 like($warn[1], qr/ wq_worker: /, '2nd warned from wq_worker');
 is($warn[2], $warn[1], 'worker did not die');
 
+$SIG{__WARN__} = 'DEFAULT';
+is($ipc->wq_workers_start('wq', 1), $$, 'workers started again');
+is(scalar(keys %{$ipc->{-wq_workers}}), 1, '1 worker started');
+$ipc->wq_worker_incr;
+is(scalar(keys %{$ipc->{-wq_workers}}), 2, 'worker count bumped');
+$ipc->wq_worker_decr;
+$ipc->wq_worker_decr_wait(10);
+is(scalar(keys %{$ipc->{-wq_workers}}), 1, 'worker count lowered');
+
 done_testing;

  parent reply	other threads:[~2021-01-10 12:15 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-10 12:14 [PATCH 00/22] lei query overview views Eric Wong
2021-01-10 12:14 ` [PATCH 01/22] lei query + pagination sorta working Eric Wong
2021-01-10 12:14 ` [PATCH 02/22] lei q: deduplicate smsg Eric Wong
2021-01-10 12:15 ` [PATCH 03/22] ds: block signals when reaping Eric Wong
2021-01-10 12:15 ` [PATCH 04/22] ipc: add support for asynchronous callbacks Eric Wong
2021-01-10 12:15 ` [PATCH 05/22] cmd_ipc: send FDs with buffer payload Eric Wong
2021-01-10 12:15 ` [PATCH 06/22] ipc: avoid excessive evals Eric Wong
2021-01-10 12:15 ` [PATCH 07/22] ipc: work queue support via SOCK_SEQPACKET Eric Wong
2021-01-10 12:15 ` [PATCH 08/22] ipc: eliminate ipc_worker_stop method Eric Wong
2021-01-10 12:15 ` Eric Wong [this message]
2021-01-10 12:15 ` [PATCH 10/22] ipc: drop -ipc_parent_pid field Eric Wong
2021-01-10 12:15 ` [PATCH 11/22] ipc: DESTROY and wq_workers methods Eric Wong
2021-01-10 12:15 ` [PATCH 12/22] lei: rename $w to $wpager for warning message Eric Wong
2021-01-10 12:15 ` [PATCH 13/22] lei: fix oneshot TTY detection by passing STD*{GLOB} Eric Wong
2021-01-10 12:15 ` [PATCH 14/22] lei: query: ensure pager exit is instantaneous Eric Wong
2021-01-10 12:15 ` [PATCH 15/22] ipc: start supporting sending/receiving more than 3 FDs Eric Wong
2021-01-10 12:15 ` [PATCH 16/22] ipc: fix IO::FDPass use with a worker limit of 1 Eric Wong
2021-01-10 12:15 ` [PATCH 17/22] ipc: drop unused fields, default sighandlers for wq Eric Wong
2021-01-10 12:15 ` [PATCH 18/22] lei: get rid of client {pid} field Eric Wong
2021-01-10 12:15 ` [PATCH 19/22] lei: fork + FD cleanup Eric Wong
2021-01-10 12:15 ` [PATCH 20/22] lei: run pager in client script Eric Wong
2021-01-10 12:15 ` [PATCH 21/22] lei_xsearch: transfer 4 FDs internally, drop IO::FDPass Eric Wong
2021-01-10 12:15 ` [PATCH 22/22] lei: query: restore JSON output overview Eric Wong

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