[PATCH 1/2] lei q: parallelize Maildir and mbox writing

[Eric Wong <e@80x24.org>]

With 4 dedicated workers, this seems to provide a 100-120%
speedup on a 4 core machine when writing thousands of search
results to a Maildir or mbox.  This also sets us up for
high-latency IMAP destinations in the future.

This opens the door to more speedup opportunities such
as optimizing dedupe locking and other ways to reduce
contention.

This change is fairly complex and convoluted, unfortunately.
Further work may allow us to simplify it and even improve
performance.
---
 lib/PublicInbox/IPC.pm         |  3 +++
 lib/PublicInbox/LEI.pm         | 36 ++++++++++++++++++++++++----------
 lib/PublicInbox/LeiOverview.pm | 36 +++++++++++++++++++++++++++++++---
 lib/PublicInbox/LeiQuery.pm    | 12 +++++++++---
 lib/PublicInbox/LeiToMail.pm   | 29 +++++++++++++++++++++++++++
 lib/PublicInbox/LeiXSearch.pm  | 27 +++++++++++++++----------
 lib/PublicInbox/Spawn.pm       |  2 +-
 7 files changed, 118 insertions(+), 27 deletions(-)

diff --git a/lib/PublicInbox/IPC.pm b/lib/PublicInbox/IPC.pm
index 78cb8400..8fec2e62 100644
--- a/lib/PublicInbox/IPC.pm
+++ b/lib/PublicInbox/IPC.pm
@@ -397,4 +397,7 @@ sub DESTROY {
 	ipc_worker_stop($self);
 }
 
+# Sereal doesn't have dclone
+sub deep_clone { thaw(freeze($_[-1])) }
+
 1;
diff --git a/lib/PublicInbox/LEI.pm b/lib/PublicInbox/LEI.pm
index 61f2a65b..6b6ee0f5 100644
--- a/lib/PublicInbox/LEI.pm
+++ b/lib/PublicInbox/LEI.pm
@@ -279,13 +279,21 @@ sub atfork_prepare_wq {
 	if (my $sock = $self->{sock}) {
 		push @$tcafc, @$self{qw(0 1 2)}, $sock;
 	}
+	for my $f (qw(lxs l2m)) {
+		my $ipc = $self->{$f} or next;
+		push @$tcafc, grep { defined }
+				@$ipc{qw(-wq_s1 -wq_s2 -ipc_req -ipc_res)};
+	}
 }
 
 # usage: my %sig = $lei->atfork_child_wq($wq);
 #	 local @SIG{keys %sig} = values %sig;
 sub atfork_child_wq {
 	my ($self, $wq) = @_;
-	@$self{qw(0 1 2 sock)} = delete(@$wq{0..3});
+	my ($sock, $l2m_wq_s1);
+	(@$self{qw(0 1 2)}, $sock, $l2m_wq_s1) = delete(@$wq{0..4});
+	$self->{sock} = $sock if -S $sock;
+	$self->{l2m}->{-wq_s1} = $l2m_wq_s1 if $l2m_wq_s1;
 	%PATH2CFG = ();
 	$quit = \&CORE::exit;
 	@TO_CLOSE_ATFORK_CHILD = ();
@@ -304,15 +312,23 @@ sub atfork_child_wq {
 # usage: ($lei, @io) = $lei->atfork_parent_wq($wq);
 sub atfork_parent_wq {
 	my ($self, $wq) = @_;
-	if ($wq->wq_workers) {
-		my $env = delete $self->{env}; # env is inherited at fork
-		my $ret = bless { %$self }, ref($self);
-		$self->{env} = $env;
-		delete @$ret{qw(-lei_store cfg pgr)};
-		($ret, delete @$ret{0..2}, delete($ret->{sock}) // ());
-	} else {
-		($self, @$self{0..2}, $self->{sock} // ());
+	my $env = delete $self->{env}; # env is inherited at fork
+	my $ret = bless { %$self }, ref($self);
+	if (my $dedupe = delete $ret->{dedupe}) {
+		$ret->{dedupe} = $wq->deep_clone($dedupe);
+	}
+	$self->{env} = $env;
+	delete @$ret{qw(-lei_store cfg pgr lxs)}; # keep l2m
+	my @io = delete @$ret{0..2};
+	$io[3] = delete($ret->{sock}) // *STDERR{GLOB};
+	my $l2m = $ret->{l2m};
+	if ($l2m && $l2m != $wq) {
+		$io[4] = $l2m->{-wq_s1} if $l2m->{-wq_s1};
+		if (my @pids = $l2m->wq_close) {
+			$wq->{l2m_pids} = \@pids;
+		}
 	}
+	($ret, @io);
 }
 
 sub _help ($;$) {
@@ -656,7 +672,7 @@ sub start_mua {
 	@cmd = map { $_ eq '%f' ? ($replaced = $mfolder) : $_ } @cmd;
 	push @cmd, $mfolder unless defined($replaced);
 	$sock //= $self->{sock};
-	if ($sock) { # lei(1) client process runs it
+	if ($PublicInbox::DS::in_loop) { # lei(1) client process runs it
 		send($sock, exec_buf(\@cmd, {}), MSG_EOR);
 	} else { # oneshot
 		$self->{"mua.pid.$self.$$"} = spawn(\@cmd);
diff --git a/lib/PublicInbox/LeiOverview.pm b/lib/PublicInbox/LeiOverview.pm
index c0b423f6..538d6bd5 100644
--- a/lib/PublicInbox/LeiOverview.pm
+++ b/lib/PublicInbox/LeiOverview.pm
@@ -140,6 +140,16 @@ sub _unbless_smsg {
 
 sub ovv_atexit_child {
 	my ($self, $lei) = @_;
+	if (my $l2m = delete $lei->{l2m}) {
+		# gracefully stop lei2mail processes after all
+		# ->write_mail work is complete
+		delete $l2m->{-wq_s1};
+		if (my $rd = delete $l2m->{each_smsg_done}) {
+			read($rd, my $buf, 1); # wait for EOF
+		}
+	}
+	# order matters, git->{-tmp}->DESTROY must not fire until
+	# {each_smsg_done} hits EOF above
 	if (my $git = delete $self->{git}) {
 		$git->async_wait_all;
 	}
@@ -178,8 +188,6 @@ sub _json_pretty {
 
 sub ovv_each_smsg_cb { # runs in wq worker usually
 	my ($self, $lei, $ibxish) = @_;
-	$lei->{ovv_buf} = \(my $buf = '');
-	delete(@$self{qw(lock_path tmp_lk_id)}) unless $lei->{-parallel};
 	my $json;
 	$lei->{1}->autoflush(1);
 	if (my $pkg = $self->{json}) {
@@ -187,7 +195,27 @@ sub ovv_each_smsg_cb { # runs in wq worker usually
 		$json->utf8->canonical;
 		$json->ascii(1) if $lei->{opt}->{ascii};
 	}
-	if (my $l2m = $lei->{l2m}) {
+	my $l2m = $lei->{l2m};
+	if ($l2m && $l2m->{-wq_s1}) {
+		my ($lei_ipc, @io) = $lei->atfork_parent_wq($l2m);
+		# n.b. $io[0] = qry_status_wr, $io[1] = mbox|stdout,
+		# $io[4] becomes a notification pipe that triggers EOF
+		# in this wq worker when all outstanding ->write_mail
+		# calls are complete
+		die "BUG: \$io[4] $io[4] unexpected" if $io[4];
+		pipe($l2m->{each_smsg_done}, $io[4]) or die "pipe: $!";
+		fcntl($io[4], 1031, 4096) if $^O eq 'linux';
+		delete @$lei_ipc{qw(l2m opt mset_opt cmd)};
+		my $git = $ibxish->git; # (LeiXSearch|Inbox|ExtSearch)->git
+		$self->{git} = $git;
+		my $git_dir = $git->{git_dir};
+		sub {
+			my ($smsg, $mitem) = @_;
+			my $kw = []; # TODO get from mitem
+			$l2m->wq_do('write_mail', \@io, $git_dir,
+					$smsg->{blob}, $lei_ipc, $kw)
+		}
+	} elsif ($l2m) {
 		my $wcb = $l2m->write_cb($lei);
 		my $git = $ibxish->git; # (LeiXSearch|Inbox|ExtSearch)->git
 		$self->{git} = $git; # for ovv_atexit_child
@@ -199,6 +227,7 @@ sub ovv_each_smsg_cb { # runs in wq worker usually
 		};
 	} elsif ($self->{fmt} =~ /\A(concat)?json\z/ && $lei->{opt}->{pretty}) {
 		my $EOR = ($1//'') eq 'concat' ? "\n}" : "\n},";
+		$lei->{ovv_buf} = \(my $buf = '');
 		sub { # DIY prettiness :P
 			my ($smsg, $mitem) = @_;
 			$smsg = _unbless_smsg($smsg, $mitem);
@@ -221,6 +250,7 @@ sub ovv_each_smsg_cb { # runs in wq worker usually
 		}
 	} elsif ($json) {
 		my $ORS = $self->{fmt} eq 'json' ? ",\n" : "\n"; # JSONL
+		$lei->{ovv_buf} = \(my $buf = '');
 		sub {
 			my ($smsg, $mitem) = @_;
 			delete @$smsg{qw(tid num)};
diff --git a/lib/PublicInbox/LeiQuery.pm b/lib/PublicInbox/LeiQuery.pm
index a80d5887..d6e801e3 100644
--- a/lib/PublicInbox/LeiQuery.pm
+++ b/lib/PublicInbox/LeiQuery.pm
@@ -41,11 +41,17 @@ sub lei_q {
 	$j = 1 if !$opt->{thread};
 	$j++ if $opt->{'local'}; # for sto->search below
 	$self->atfork_prepare_wq($lxs);
-	$lxs->wq_workers_start('lei_xsearch', $j, $self->oldset)
-		// $lxs->wq_workers($j);
+	$lxs->wq_workers_start('lei_xsearch', $j, $self->oldset);
+	$self->{lxs} = $lxs;
 
-	# no forking workers after this
 	my $ovv = PublicInbox::LeiOverview->new($self) or return;
+	if (my $l2m = $self->{l2m}) {
+		$j = 4 if $j <= 4; # TODO configurable
+		$self->atfork_prepare_wq($l2m);
+		$l2m->wq_workers_start('lei2mail', $j, $self->oldset);
+	}
+
+	# no forking workers after this
 	my $sto = $self->_lei_store(1);
 	unshift(@srcs, $sto->search) if $opt->{'local'};
 	my %mset_opt = map { $_ => $opt->{$_} } qw(thread limit offset);
diff --git a/lib/PublicInbox/LeiToMail.pm b/lib/PublicInbox/LeiToMail.pm
index 0e23b8da..17d48a90 100644
--- a/lib/PublicInbox/LeiToMail.pm
+++ b/lib/PublicInbox/LeiToMail.pm
@@ -5,6 +5,7 @@
 package PublicInbox::LeiToMail;
 use strict;
 use v5.10.1;
+use parent qw(PublicInbox::IPC);
 use PublicInbox::Eml;
 use PublicInbox::Lock;
 use PublicInbox::ProcessPipe;
@@ -14,6 +15,8 @@ use Symbol qw(gensym);
 use IO::Handle; # ->autoflush
 use Fcntl qw(SEEK_SET SEEK_END O_CREAT O_EXCL O_WRONLY);
 use Errno qw(EEXIST ESPIPE ENOENT);
+use File::Temp 0.19 (); # 0.19 for ->newdir
+use PublicInbox::Git;
 
 my %kw2char = ( # Maildir characters
 	draft => 'D',
@@ -422,4 +425,30 @@ sub lock_free {
 	$_[0]->{base_type} =~ /\A(?:maildir|mh|imap|jmap)\z/ ? 1 : 0;
 }
 
+sub write_mail { # via ->wq_do
+	my ($self, $git_dir, $oid, $lei, $kw) = @_;
+	my $wcb = $self->{wcb} //= do { # first message
+		my %sig = $lei->atfork_child_wq($self);
+		@SIG{keys %sig} = values %sig; # not local
+		$lei->{dedupe}->prepare_dedupe;
+		$self->write_cb($lei);
+	};
+	my $git = $self->{"$$\0$git_dir"} //= PublicInbox::Git->new($git_dir);
+	$git->cat_async($oid, \&git_to_mail, [ $wcb, $kw ]);
+}
+
+sub ipc_atfork_prepare {
+	my ($self) = @_;
+	# (qry_status_wr, stdout|mbox, stderr, 3: sock, 4: each_smsg_done_wr)
+	$self->wq_set_recv_modes(qw[+<&= >&= >&= +<&= >&=]);
+	$self->SUPER::ipc_atfork_prepare; # PublicInbox::IPC
+}
+
+sub DESTROY {
+	my ($self) = @_;
+	for my $pid_git (grep(/\A$$\0/, keys %$self)) {
+		$self->{$pid_git}->async_wait_all;
+	}
+}
+
 1;
diff --git a/lib/PublicInbox/LeiXSearch.pm b/lib/PublicInbox/LeiXSearch.pm
index 91864cd0..dc5cf3b6 100644
--- a/lib/PublicInbox/LeiXSearch.pm
+++ b/lib/PublicInbox/LeiXSearch.pm
@@ -126,6 +126,7 @@ sub query_thread_mset { # for --thread
 			@{$ctx->{xids}} = ();
 		}
 	} while (_mset_more($mset, $mo));
+	undef $each_smsg; # drops @io for l2m->{each_smsg_done}
 	$lei->{ovv}->ovv_atexit_child($lei);
 }
 
@@ -147,6 +148,7 @@ sub query_mset { # non-parallel for non-"--thread" users
 			$each_smsg->($smsg, $it);
 		}
 	} while (_mset_more($mset, $mo));
+	undef $each_smsg; # drops @io for l2m->{each_smsg_done}
 	$lei->{ovv}->ovv_atexit_child($lei);
 }
 
@@ -170,11 +172,14 @@ sub git {
 }
 
 sub query_done { # EOF callback
-	my ($lei) = @_;
-	$lei->{ovv}->ovv_end($lei);
-	if (my $l2m = $lei->{l2m}) {
-		$lei->start_mua unless $l2m->lock_free;
+	my ($self, $lei) = @_;
+	my $l2m = delete $lei->{l2m};
+	if (my $pids = delete $self->{l2m_pids}) {
+		my $ipc_worker_reap = $self->can('ipc_worker_reap');
+		dwaitpid($_, $ipc_worker_reap, $l2m) for @$pids;
 	}
+	$lei->{ovv}->ovv_end($lei);
+	$lei->start_mua if $l2m && !$l2m->lock_free;
 	$lei->dclose;
 }
 
@@ -188,12 +193,10 @@ sub start_query { # always runs in main (lei-daemon) process
 	}
 	my $remotes = $self->{remotes} // [];
 	if ($lei->{opt}->{thread}) {
-		$lei->{-parallel} = scalar(@$remotes) + scalar(@$srcs) - 1;
 		for my $ibxish (@$srcs) {
 			$self->wq_do('query_thread_mset', $io, $lei, $ibxish);
 		}
 	} else {
-		$lei->{-parallel} = scalar(@$remotes);
 		$self->wq_do('query_mset', $io, $lei, $srcs);
 	}
 	# TODO
@@ -226,12 +229,12 @@ sub do_query {
 	$io[0] = undef;
 	pipe(my $qry_status_rd, $io[0]) or die "pipe $!";
 
-	$lei_orig->{lxs} = $self;
 	$lei_orig->event_step_init; # wait for shutdowns
-	my $op_map = { '' => [ \&query_done, $lei_orig ] };
+	my $op_map = { '' => [ \&query_done, $self, $lei_orig ] };
 	my $in_loop = exists $lei_orig->{sock};
 	my $opp = PublicInbox::OpPipe->new($qry_status_rd, $op_map, $in_loop);
-	if (my $l2m = $lei->{l2m}) {
+	my $l2m = $lei->{l2m};
+	if ($l2m) {
 		$l2m->pre_augment($lei_orig); # may redirect $lei->{1} for mbox
 		$io[1] = $lei_orig->{1};
 		$op_map->{'.'} = [ \&start_query, $self, \@io, $lei, $srcs ];
@@ -246,13 +249,17 @@ sub do_query {
 		$op_map->{'!'} = [ \&CORE::kill, 'TERM', @pids ];
 		$opp->event_step;
 		my $ipc_worker_reap = $self->can('ipc_worker_reap');
+		if (my $l2m_pids = delete $self->{l2m_pids}) {
+			dwaitpid($_, $ipc_worker_reap, $l2m) for @$l2m_pids;
+		}
 		dwaitpid($_, $ipc_worker_reap, $self) for @pids;
 	}
 }
 
 sub ipc_atfork_prepare {
 	my ($self) = @_;
-	$self->wq_set_recv_modes(qw[+<&= >&= >&= +<&=]);
+	# (qry_status_wr, stdout|mbox, stderr, 3: sock, 4: $l2m->{-wq_s1})
+	$self->wq_set_recv_modes(qw[+<&= >&= >&= +<&= +<&=]);
 	$self->SUPER::ipc_atfork_prepare; # PublicInbox::IPC
 }
 
diff --git a/lib/PublicInbox/Spawn.pm b/lib/PublicInbox/Spawn.pm
index e5c0b1e9..b03f2d59 100644
--- a/lib/PublicInbox/Spawn.pm
+++ b/lib/PublicInbox/Spawn.pm
@@ -209,7 +209,7 @@ my $fdpass = <<'FDPASS';
 #include <sys/socket.h>
 
 #if defined(CMSG_SPACE) && defined(CMSG_LEN)
-#define SEND_FD_CAPA 4
+#define SEND_FD_CAPA 5
 #define SEND_FD_SPACE (SEND_FD_CAPA * sizeof(int))
 union my_cmsg {
 	struct cmsghdr hdr;