[PATCH 0/4] more xap_helper updates

[PATCH 0/4] more xap_helper updates

[Eric Wong]

Eric Wong (4):
  test_common: don't needlessly rebuild C++ Xapian helper
  search: remove auto-start for async_mset
  xap_helper: reopen logs in daemons
  xap_helper: implement alarm(2)-based timeout

 lib/PublicInbox/Daemon.pm     | 37 ++++++++++++++++-------
 lib/PublicInbox/Search.pm     |  1 -
 lib/PublicInbox/TestCommon.pm | 13 ++++----
 lib/PublicInbox/XapHelper.pm  | 23 ++++++++++++--
 lib/PublicInbox/xap_helper.h  | 56 +++++++++++++++++++++++++++++++++--
 t/psgi_v2.t                   | 54 +++++++++++++++++++++++++++++++++
 t/xap_helper.t                | 15 ++++++++++
 7 files changed, 177 insertions(+), 22 deletions(-)

[PATCH 1/4] test_common: don't needlessly rebuild C++ Xapian helper

[Eric Wong]

We should almost always be calling `check_build' instead of
`build'.  Using ccache masked some of the overhead from
this, but various linker implementations are still slow.
---
 lib/PublicInbox/TestCommon.pm | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/PublicInbox/TestCommon.pm b/lib/PublicInbox/TestCommon.pm
index b8b7b827..708fa698 100644
--- a/lib/PublicInbox/TestCommon.pm
+++ b/lib/PublicInbox/TestCommon.pm
@@ -726,7 +726,7 @@ SKIP: {
 	require File::Path;
 	eval { # use XDG_CACHE_HOME, first:
 		require PublicInbox::XapHelperCxx;
-		PublicInbox::XapHelperCxx::build();
+		PublicInbox::XapHelperCxx::check_build();
 	};
 	local %ENV = %ENV;
 	delete $ENV{XDG_DATA_HOME};

[PATCH 2/4] search: remove auto-start for async_mset

[Eric Wong]

Only public-facing daemons use it, currently, and all
public-facing daemons will pre-spawn it as early as feasible.
lei will need it eventually to handle queries requiring C++,
but I'm not certain what path to take with lei, yet...
---
 lib/PublicInbox/Search.pm | 1 -
 1 file changed, 1 deletion(-)

diff --git a/lib/PublicInbox/Search.pm b/lib/PublicInbox/Search.pm
index 4adef366..fbdb48a3 100644
--- a/lib/PublicInbox/Search.pm
+++ b/lib/PublicInbox/Search.pm
@@ -465,7 +465,6 @@ sub xh_opt ($) {
 # and a falsy value if handled synchronously
 sub async_mset {
 	my ($self, $qry_str, $opt, $cb, @args) = @_;
-	$XHC //= xhc_start_maybe;
 	if ($XHC) { # unconditionally retrieving pct + rank for now
 		xdb($self); # populate {nshards}
 		my @margs = ($self->xh_args, xh_opt($opt));

[PATCH 3/4] xap_helper: reopen logs in daemons

[Eric Wong]

When read-only daemons reopen log files via SIGUSR1, be sure to
propagate it to Xapian helper processes to ensure old log files
can be closed and archived.
---
 lib/PublicInbox/Daemon.pm     | 37 +++++++++++++++++-------
 lib/PublicInbox/TestCommon.pm | 11 +++----
 lib/PublicInbox/XapHelper.pm  | 16 ++++++++++-
 lib/PublicInbox/xap_helper.h  | 43 ++++++++++++++++++++++++++--
 t/psgi_v2.t                   | 54 +++++++++++++++++++++++++++++++++++
 5 files changed, 142 insertions(+), 19 deletions(-)

diff --git a/lib/PublicInbox/Daemon.pm b/lib/PublicInbox/Daemon.pm
index e08102e9..28458b19 100644
--- a/lib/PublicInbox/Daemon.pm
+++ b/lib/PublicInbox/Daemon.pm
@@ -388,10 +388,30 @@ sub worker_quit { # $_[0] = signal name or number (unused)
 	@PublicInbox::DS::post_loop_do = (\&has_busy_clients, { -w => 0 })
 }
 
+sub spawn_xh () {
+	$xh_workers // return;
+	require PublicInbox::XhcMset;
+	local $) = $gid if defined $gid;
+	local $( = $gid if defined $gid;
+	local $> = $uid if defined $uid;
+	local $< = $uid if defined $uid;
+	$PublicInbox::Search::XHC = eval {
+		local $ENV{STDERR_PATH} = $stderr;
+		local $ENV{STDOUT_PATH} = $stdout;
+		PublicInbox::XapClient::start_helper('-j', $xh_workers)
+	};
+	warn "E: $@" if $@;
+	awaitpid($PublicInbox::Search::XHC->{io}->attached_pid, \&respawn_xh)
+		if $PublicInbox::Search::XHC;
+}
+
 sub reopen_logs {
+	my ($sig) = @_;
 	$logs{$stdout} //= \*STDOUT if defined $stdout;
 	$logs{$stderr} //= \*STDERR if defined $stderr;
 	while (my ($p, $fh) = each %logs) { open_log_path($fh, $p) }
+	($sig && defined($xh_workers) && $PublicInbox::Search::XHC) and
+		kill('USR1', $PublicInbox::Search::XHC->{io}->attached_pid);
 }
 
 sub sockname ($) {
@@ -548,6 +568,7 @@ sub start_worker ($) {
 	my $pid = PublicInbox::DS::fork_persist;
 	if ($pid == 0) {
 		undef %WORKERS;
+		undef $xh_workers;
 		local $PublicInbox::DS::Poller; # allow epoll/kqueue
 		$set_user->() if $set_user;
 		PublicInbox::EOFpipe->new($parent_pipe, \&worker_quit);
@@ -575,8 +596,9 @@ sub master_loop {
 	pipe($parent_pipe, my $p1) or die "failed to create parent-pipe: $!";
 	my $set_workers = $nworker; # for SIGWINCH
 	reopen_logs();
+	spawn_xh;
 	my $msig = {
-		USR1 => sub { reopen_logs(); kill_workers($_[0]); },
+		USR1 => sub { reopen_logs($_[0]); kill_workers($_[0]); },
 		USR2 => \&upgrade,
 		QUIT => \&master_quit,
 		INT => \&master_quit,
@@ -675,6 +697,7 @@ sub daemon_loop () {
 sub worker_loop {
 	$uid = $gid = undef;
 	reopen_logs();
+	spawn_xh; # only for -W0
 	@listeners = map {;
 		my $l = sockname($_);
 		my $tls_cb = $POST_ACCEPT{$l};
@@ -695,8 +718,7 @@ sub respawn_xh { # awaitpid cb
 	my ($pid) = @_;
 	return unless @listeners;
 	warn "W: xap_helper PID:$pid died: \$?=$?, respawning...\n";
-	$PublicInbox::Search::XHC =
-		PublicInbox::XapClient::start_helper('-j', $xh_workers);
+	spawn_xh;
 }
 
 sub run {
@@ -712,14 +734,7 @@ sub run {
 	local $SIG{__WARN__} = PublicInbox::Eml::warn_ignore_cb();
 	local %WORKER_SIG = %WORKER_SIG;
 	local $PublicInbox::XapClient::tries = 0;
-
-	local $PublicInbox::Search::XHC = PublicInbox::XapClient::start_helper(
-			'-j', $xh_workers) if defined($xh_workers);
-	if ($PublicInbox::Search::XHC) {
-		require PublicInbox::XhcMset;
-		awaitpid($PublicInbox::Search::XHC->{io}->attached_pid,
-			\&respawn_xh);
-	}
+	local $PublicInbox::Search::XHC if defined($xh_workers);
 
 	daemon_loop();
 	# $unlink_on_leave runs
diff --git a/lib/PublicInbox/TestCommon.pm b/lib/PublicInbox/TestCommon.pm
index 708fa698..aeff5d1d 100644
--- a/lib/PublicInbox/TestCommon.pm
+++ b/lib/PublicInbox/TestCommon.pm
@@ -20,7 +20,7 @@ use autodie qw(chdir close fcntl mkdir open opendir seek unlink);
 $ENV{XDG_CACHE_HOME} //= "$ENV{HOME}/.cache"; # reuse C++ xap_helper builds
 
 $_ = File::Spec->rel2abs($_) for (grep(!m!^/!, @INC));
-
+our $CURRENT_DAEMON;
 BEGIN {
 	@EXPORT = qw(tmpdir tcp_server tcp_connect require_git require_mods
 		run_script start_script key2sub xsys xsys_e xqx eml_load tick
@@ -566,9 +566,9 @@ sub start_script {
 	my $run_mode = $ENV{TEST_RUN_MODE} // $opt->{run_mode} // 2;
 	my $sub = $run_mode == 0 ? undef : key2sub($key);
 	my $tail;
-	my $xh = $ENV{TEST_DAEMON_XH};
-	$xh && $key =~ /-(?:imapd|netd|httpd|pop3d|nntpd)\z/ and
-		push @argv, split(/\s+/, $xh);
+	my @xh = split(/\s+/, $ENV{TEST_DAEMON_XH} // '');
+	@xh = () if $key !~ /-(?:imapd|netd|httpd|pop3d|nntpd)\z/;
+	push @argv, @xh;
 	if ($tail_cmd) {
 		my @paths;
 		for (@argv) {
@@ -616,7 +616,7 @@ sub start_script {
 			$ENV{LISTEN_FDS} = $fds;
 		}
 		if ($opt->{-C}) { chdir($opt->{-C}) }
-		$0 = join(' ', @$cmd);
+		$0 = join(' ', @$cmd, @xh);
 		local @SIG{keys %SIG} = map { undef } values %SIG;
 		local $SIG{FPE} = 'IGNORE'; # Perl default
 		undef $tmp_mask;
@@ -952,6 +952,7 @@ sub test_httpd ($$;$$) {
 		local $ENV{PLACK_TEST_EXTERNALSERVER_URI} = "http://$h:$p";
 		my $ua = LWP::UserAgent->new;
 		$ua->max_redirect(0);
+		local $CURRENT_DAEMON = $td;
 		Plack::Test::ExternalServer::test_psgi(client => $client,
 							ua => $ua);
 		$cb->() if $cb;
diff --git a/lib/PublicInbox/XapHelper.pm b/lib/PublicInbox/XapHelper.pm
index c55a72ce..746b4d62 100644
--- a/lib/PublicInbox/XapHelper.pm
+++ b/lib/PublicInbox/XapHelper.pm
@@ -200,6 +200,7 @@ sub recv_loop {
 	local $SIG{__WARN__} = sub { print $stderr @_ };
 	my $rbuf;
 	local $SIG{TERM} = sub { undef $in };
+	local $SIG{USR1} = \&reopen_logs;
 	while (defined($in)) {
 		PublicInbox::DS::sig_setmask($workerset);
 		my @fds = eval { # we undef $in in SIG{TERM}
@@ -263,6 +264,18 @@ sub do_sigttou {
 	}
 }
 
+sub reopen_logs {
+	my $p = $ENV{STDOUT_PATH};
+	defined($p) && open(STDOUT, '>>', $p) and STDOUT->autoflush(1);
+	$p = $ENV{STDERR_PATH};
+	defined($p) && open(STDERR, '>>', $p) and STDERR->autoflush(1);
+}
+
+sub parent_reopen_logs {
+	reopen_logs();
+	kill('USR1', values %WORKERS);
+}
+
 sub xh_alive { $in || scalar(keys %WORKERS) }
 
 sub start (@) {
@@ -276,7 +289,7 @@ sub start (@) {
 		die 'bad args';
 	local $workerset = POSIX::SigSet->new;
 	$workerset->fillset or die "fillset: $!";
-	for (@PublicInbox::DS::UNBLOCKABLE) {
+	for (@PublicInbox::DS::UNBLOCKABLE, POSIX::SIGUSR1) {
 		$workerset->delset($_) or die "delset($_): $!";
 	}
 
@@ -295,6 +308,7 @@ sub start (@) {
 		},
 		TTOU => \&do_sigttou,
 		CHLD => \&PublicInbox::DS::enqueue_reap,
+		USR1 => \&parent_reopen_logs,
 	};
 	PublicInbox::DS::block_signals();
 	start_workers();
diff --git a/lib/PublicInbox/xap_helper.h b/lib/PublicInbox/xap_helper.h
index 5a89544a..7ecea264 100644
--- a/lib/PublicInbox/xap_helper.h
+++ b/lib/PublicInbox/xap_helper.h
@@ -95,6 +95,8 @@ static pid_t *worker_pids; // nr => pid
 #define WORKER_MAX USHRT_MAX
 static unsigned long nworker, nworker_hwm;
 static int pipefds[2];
+static const char *stdout_path, *stderr_path; // for SIGUSR1
+static sig_atomic_t worker_needs_reopen;
 
 // PublicInbox::Search and PublicInbox::CodeSearch generate these:
 static void mail_nrp_init(void);
@@ -726,9 +728,12 @@ static void stderr_restore(FILE *tmp_err)
 	clearerr(stderr);
 }
 
-static void sigw(int sig) // SIGTERM handler for worker
+static void sigw(int sig) // SIGTERM+SIGUSR1 handler for worker
 {
-	sock_fd = -1; // break out of recv_loop
+	switch (sig) {
+	case SIGUSR1: worker_needs_reopen = 1; break;
+	default: sock_fd = -1; // break out of recv_loop
+	}
 }
 
 #define CLEANUP_REQ __attribute__((__cleanup__(req_cleanup)))
@@ -738,6 +743,18 @@ static void req_cleanup(void *ptr)
 	free(req->lenv);
 }
 
+static void reopen_logs(void)
+{
+	if (stdout_path && *stdout_path && !freopen(stdout_path, "a", stdout))
+		err(EXIT_FAILURE, "freopen %s", stdout_path);
+	if (stderr_path && *stderr_path) {
+		if (!freopen(stderr_path, "a", stderr))
+			err(EXIT_FAILURE, "freopen %s", stderr_path);
+		if (my_setlinebuf(stderr))
+			err(EXIT_FAILURE, "setlinebuf(stderr)");
+	}
+}
+
 static void recv_loop(void) // worker process loop
 {
 	static char rbuf[4096 * 33]; // per-process
@@ -745,6 +762,7 @@ static void recv_loop(void) // worker process loop
 	sa.sa_handler = sigw;
 
 	CHECK(int, 0, sigaction(SIGTERM, &sa, NULL));
+	CHECK(int, 0, sigaction(SIGUSR1, &sa, NULL));
 
 	while (sock_fd == 0) {
 		size_t len = sizeof(rbuf);
@@ -761,6 +779,10 @@ static void recv_loop(void) // worker process loop
 			stderr_restore(req.fp[1]);
 			ERR_CLOSE(req.fp[1], 0);
 		}
+		if (worker_needs_reopen) {
+			worker_needs_reopen = 0;
+			reopen_logs();
+		}
 	}
 }
 
@@ -813,6 +835,16 @@ static void cleanup_all(void)
 #endif
 }
 
+static void parent_reopen_logs(void)
+{
+	reopen_logs();
+	for (unsigned long nr = nworker; nr < nworker_hwm; nr++) {
+		pid_t pid = worker_pids[nr];
+		if (pid != 0 && kill(pid, SIGUSR1))
+			warn("BUG?: kill(%d, SIGUSR1)", (int)pid);
+	}
+}
+
 static void sigp(int sig) // parent signal handler
 {
 	static const char eagain[] = "signals coming in too fast";
@@ -825,6 +857,7 @@ static void sigp(int sig) // parent signal handler
 	case SIGCHLD: c = '.'; break;
 	case SIGTTOU: c = '-'; break;
 	case SIGTTIN: c = '+'; break;
+	case SIGUSR1: c = '#'; break;
 	default:
 		write(STDERR_FILENO, bad_sig, sizeof(bad_sig) - 1);
 		_exit(EXIT_FAILURE);
@@ -931,6 +964,8 @@ int main(int argc, char *argv[])
 {
 	int c;
 	socklen_t slen = (socklen_t)sizeof(c);
+	stdout_path = getenv("STDOUT_PATH");
+	stderr_path = getenv("STDERR_PATH");
 
 	if (getsockopt(sock_fd, SOL_SOCKET, SO_TYPE, &c, &slen))
 		err(EXIT_FAILURE, "getsockopt");
@@ -989,6 +1024,7 @@ int main(int argc, char *argv[])
 	DELSET(SIGXCPU);
 	DELSET(SIGXFSZ);
 #undef DELSET
+	CHECK(int, 0, sigdelset(&workerset, SIGUSR1));
 
 	if (nworker == 0) { // no SIGTERM handling w/o workers
 		recv_loop();
@@ -1009,10 +1045,12 @@ int main(int argc, char *argv[])
 	CHECK(int, 0, sigdelset(&pset, SIGCHLD));
 	CHECK(int, 0, sigdelset(&pset, SIGTTIN));
 	CHECK(int, 0, sigdelset(&pset, SIGTTOU));
+	CHECK(int, 0, sigdelset(&pset, SIGUSR1));
 
 	struct sigaction sa = {};
 	sa.sa_handler = sigp;
 
+	CHECK(int, 0, sigaction(SIGUSR1, &sa, NULL));
 	CHECK(int, 0, sigaction(SIGTTIN, &sa, NULL));
 	CHECK(int, 0, sigaction(SIGTTOU, &sa, NULL));
 	sa.sa_flags = SA_NOCLDSTOP;
@@ -1037,6 +1075,7 @@ int main(int argc, char *argv[])
 			case '.': break; // do_sigchld already called
 			case '-': do_sigttou(); break;
 			case '+': do_sigttin(); break;
+			case '#': parent_reopen_logs(); break;
 			default: errx(EXIT_FAILURE, "BUG: c=%c", sbuf[i]);
 			}
 		}
diff --git a/t/psgi_v2.t b/t/psgi_v2.t
index d5c328f0..2b678fd8 100644
--- a/t/psgi_v2.t
+++ b/t/psgi_v2.t
@@ -9,6 +9,7 @@ require_git(2.6);
 use PublicInbox::Eml;
 use PublicInbox::Config;
 use PublicInbox::MID qw(mids);
+use autodie qw(kill rename);
 require_mods(qw(DBD::SQLite Xapian HTTP::Request::Common Plack::Test
 		URI::Escape Plack::Builder HTTP::Date));
 use_ok($_) for (qw(HTTP::Request::Common Plack::Test));
@@ -394,4 +395,57 @@ my $client3 = sub {
 test_psgi(sub { $www->call(@_) }, $client3);
 test_httpd($env, $client3, 4);
 
+if ($^O eq 'linux' && -r "/proc/$$/stat") {
+	my $args;
+	my $search_xh_pid = sub {
+		my ($pid) = @_;
+		for my $f (glob('/proc/*/stat')) {
+			open my $fh, '<', $f or next;
+			my @s = split /\s+/, readline($fh) // next;
+			next if $s[3] ne $pid; # look for matching PPID
+			open $fh, '<', "/proc/$s[0]/cmdline" or next;
+			my $cmdline = readline($fh) // next;
+			if ($cmdline =~ /\0-MPublicInbox::XapHelper\0-e\0/ ||
+					$cmdline =~ m!/xap_helper\0!) {
+				return $s[0];
+			}
+		}
+		undef;
+	};
+	my $usr1_test = sub {
+		my ($cb) = @_;
+		my $td = $PublicInbox::TestCommon::CURRENT_DAEMON;
+		my $pid = $td->{pid};
+		my $res = $cb->(GET('/v2test/?q=m:a-mid@b'));
+		is $res->code, 200, '-httpd is running w/ search';
+
+		$search_xh_pid->($pid);
+		my $xh_pid = $search_xh_pid->($pid) or
+			BAIL_OUT "can't find XH pid with $args";
+		my $xh_err = readlink "/proc/$xh_pid/fd/2";
+		is $xh_err, "$env->{TMPDIR}/stderr.log",
+			"initial stderr expected ($args)";
+		rename "$env->{TMPDIR}/stderr.log",
+			"$env->{TMPDIR}/stderr.old";
+		$xh_err = readlink "/proc/$xh_pid/fd/2";
+		is $xh_err, "$env->{TMPDIR}/stderr.old",
+			"stderr followed rename ($args)";
+		kill 'USR1', $pid;
+		tick;
+		$res = $cb->(GET('/v2test/?q=m:a-mid@b'));
+		is $res->code, 200, '-httpd still running w/ search';
+		my $new_xh_pid = $search_xh_pid->($pid) or
+			BAIL_OUT "can't find new XH pid with $args";
+		is $new_xh_pid, $xh_pid, "XH pid unchanged ($args)";
+		$xh_err = readlink "/proc/$new_xh_pid/fd/2";
+		is $xh_err, "$env->{TMPDIR}/stderr.log",
+			"stderr updated ($args)";
+	};
+	for my $x ('-X0', '-X1', '-X0 -W1', '-X1 -W1') {
+		$args = $x;
+		local $ENV{TEST_DAEMON_XH} = $args;
+		test_httpd($env, $usr1_test);
+	}
+}
+
 done_testing;

[PATCH 4/4] xap_helper: implement alarm(2)-based timeout

[Eric Wong]

alarm(2) delivering SIGALRM seems sufficient for Xapian since
Xapian doesn't block signals (which would necessitate the use of
SIGKILL via RLIMIT_CPU hard limit).  When Xapian gets stuck in
`D' state on slow storage, SIGKILL would not make a difference,
either (at least not on Linux).

Relying on RLIMIT_CPU is also trickier since we must account for
CPU time already consumed by a process for unrelated requests.
Thus we just rely on a simple alarm-based timeout.  This also
avoids requiring the optional BSD::Resource module in the (mostly)
Perl implementation (and avoids potential bugs given my meager
arithmetic skills).
---
 lib/PublicInbox/XapHelper.pm |  7 ++++++-
 lib/PublicInbox/xap_helper.h | 13 +++++++++++++
 t/xap_helper.t               | 15 +++++++++++++++
 3 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/lib/PublicInbox/XapHelper.pm b/lib/PublicInbox/XapHelper.pm
index 746b4d62..2e20660e 100644
--- a/lib/PublicInbox/XapHelper.pm
+++ b/lib/PublicInbox/XapHelper.pm
@@ -27,6 +27,8 @@ sub cmd_test_inspect {
 		($req->{srch}->has_threadid ? 1 : 0)
 }
 
+sub cmd_test_sleep { select(undef, undef, undef, 0.01) while 1 }
+
 sub iter_retry_check ($) {
 	if (ref($@) =~ /\bDatabaseModifiedError\b/) {
 		$_[0]->{srch}->reopen;
@@ -193,7 +195,10 @@ sub dispatch {
 		$new->{qp} = $new->qparse_new;
 		$new;
 	};
+	my $timeo = $req->{K};
+	alarm($timeo) if $timeo;
 	$fn->($req, @argv);
+	alarm(0) if $timeo;
 }
 
 sub recv_loop {
@@ -212,7 +217,7 @@ sub recv_loop {
 		}
 		scalar(@fds) or exit(66); # EX_NOINPUT
 		die "recvmsg: $!" if !defined($fds[0]);
-		PublicInbox::DS::block_signals();
+		PublicInbox::DS::block_signals(POSIX::SIGALRM);
 		my $req = bless {}, __PACKAGE__;
 		my $i = 0;
 		open($req->{$i++}, '+<&=', $_) for @fds;
diff --git a/lib/PublicInbox/xap_helper.h b/lib/PublicInbox/xap_helper.h
index 7ecea264..3df3ce91 100644
--- a/lib/PublicInbox/xap_helper.h
+++ b/lib/PublicInbox/xap_helper.h
@@ -27,6 +27,7 @@
 #include <sys/types.h>
 #include <sys/uio.h>
 #include <sys/wait.h>
+#include <poll.h>
 
 #include <assert.h>
 #include <err.h> // BSD, glibc, and musl all have this
@@ -413,6 +414,11 @@ static bool cmd_test_inspect(struct req *req)
 	return false;
 }
 
+static bool cmd_test_sleep(struct req *req)
+{
+	for (;;) poll(NULL, 0, 10);
+	return false;
+}
 #include "xh_mset.h" // read-only (WWW, IMAP, lei) stuff
 #include "xh_cidx.h" // CodeSearchIdx.pm stuff
 
@@ -427,6 +433,7 @@ static const struct cmd_entry {
 	CMD(dump_ibx), // many inboxes
 	CMD(dump_roots), // per-cidx shard
 	CMD(test_inspect), // least common commands last
+	CMD(test_sleep), // least common commands last
 };
 
 #define MY_ARRAY_SIZE(x)	(sizeof(x)/sizeof((x)[0]))
@@ -680,6 +687,9 @@ static void dispatch(struct req *req)
 		free_srch(kbuf.srch);
 		goto cmd_err; // srch_init already warned
 	}
+	if (req->timeout_sec)
+		alarm(req->timeout_sec > UINT_MAX ?
+			UINT_MAX : (unsigned)req->timeout_sec);
 	try {
 		if (!req->fn(req))
 			warnx("`%s' failed", req->argv[0]);
@@ -688,6 +698,8 @@ static void dispatch(struct req *req)
 	} catch (...) {
 		warn("unhandled exception");
 	}
+	if (req->timeout_sec)
+		alarm(0);
 cmd_err:
 	return; // just be silent on errors, for now
 }
@@ -1025,6 +1037,7 @@ int main(int argc, char *argv[])
 	DELSET(SIGXFSZ);
 #undef DELSET
 	CHECK(int, 0, sigdelset(&workerset, SIGUSR1));
+	CHECK(int, 0, sigdelset(&fullset, SIGALRM));
 
 	if (nworker == 0) { // no SIGTERM handling w/o workers
 		recv_loop();
diff --git a/t/xap_helper.t b/t/xap_helper.t
index effe8bc5..78be8539 100644
--- a/t/xap_helper.t
+++ b/t/xap_helper.t
@@ -9,6 +9,7 @@ use Socket qw(AF_UNIX SOCK_SEQPACKET SOCK_STREAM);
 require PublicInbox::AutoReap;
 use PublicInbox::IPC;
 require PublicInbox::XapClient;
+use PublicInbox::DS qw(now);
 use autodie;
 my ($tmp, $for_destroy) = tmpdir();
 
@@ -267,6 +268,20 @@ for my $n (@NO_CXX) {
 	my @oids = (join('', @res) =~ /^([a-f0-9]{7}) /gms);
 	is $nr_out, scalar(@oids), "output count matches $xhc->{impl}" or
 		diag explain(\@res, \@err);
+
+	if ($ENV{TEST_XH_TIMEOUT}) {
+		diag 'testing timeouts...';
+		for my $j (qw(0 1)) {
+			my $t0 = now;
+			$r = $xhc->mkreq(undef, qw(test_sleep -K 1 -d),
+					$ibx_idx[0]);
+			is readline($r), undef, 'got EOF';
+			my $diff = now - $t0;
+			ok $diff < 3, "timeout didn't take too long -j$j";
+			ok $diff >= 0.9, "timeout didn't fire prematurely -j$j";
+			$xhc = PublicInbox::XapClient::start_helper('-j1');
+		}
+	}
 }
 
 done_testing;