[PATCH 11/11] http: use bigger, but shorter-lived buffers for pipes

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

Linux pipes default to 65536 bytes in size, and we want to read
external processes as fast as possible now that we don't use
Danga::Socket or buffer to heap.

However, drop the buffer ASAP if we need to wait on anything;
since idle buffers can be idle for eons.  This lets other
execution contexts can reuse that memory right away.
---
 lib/PublicInbox/HTTPD/Async.pm | 11 ++++++-----
 lib/PublicInbox/Qspawn.pm      |  2 +-
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/lib/PublicInbox/HTTPD/Async.pm b/lib/PublicInbox/HTTPD/Async.pm
index a468ed91..e195fab0 100644
--- a/lib/PublicInbox/HTTPD/Async.pm
+++ b/lib/PublicInbox/HTTPD/Async.pm
@@ -33,13 +33,13 @@ sub new {
 	$self;
 }
 
-sub main_cb ($$$) {
-	my ($http, $fh, $bref) = @_;
+sub main_cb ($$) {
+	my ($http, $fh) = @_;
 	sub {
 		my ($self) = @_;
-		my $r = sysread($self->{sock}, $$bref, 8192);
+		my $r = sysread($self->{sock}, my $buf, 65536);
 		if ($r) {
-			$fh->write($$bref); # may call $http->close
+			$fh->write($buf); # may call $http->close
 			if ($http->{sock}) { # !closed
 				$self->requeue;
 				# let other clients get some work done, too
@@ -64,7 +64,8 @@ sub async_pass {
 	# will automatically close this ($self) object.
 	$http->{forward} = $self;
 	$fh->write($$bref); # PublicInbox:HTTP::{chunked,identity}_wcb
-	my $cb = $self->{cb} = main_cb($http, $fh, $bref);
+	$$bref = undef; # we're done with this
+	my $cb = $self->{cb} = main_cb($http, $fh);
 	$cb->($self); # either hit EAGAIN or ->requeue to keep EPOLLET happy
 }
 
diff --git a/lib/PublicInbox/Qspawn.pm b/lib/PublicInbox/Qspawn.pm
index f2630a0f..8f0b9fe2 100644
--- a/lib/PublicInbox/Qspawn.pm
+++ b/lib/PublicInbox/Qspawn.pm
@@ -128,7 +128,7 @@ sub psgi_qx {
 	my $rpipe; # comes from popen_rd
 	my $async = $env->{'pi-httpd.async'};
 	my $cb = sub {
-		my $r = sysread($rpipe, my $buf, 8192);
+		my $r = sysread($rpipe, my $buf, 65536);
 		if ($async) {
 			$async->async_pass($env->{'psgix.io'}, $qx, \$buf);
 		} elsif (defined $r) {
-- 
EW