From 394af1500d35c14883d9037b5776687a0a882f35 Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Sat, 9 Oct 2021 12:03:35 +0000
Subject: [PATCH] http: avoid Perl target cache for psgi.input
By using syswrite to populate env->{psgi.input}. The substr()
call IO::Handle->write will trigger Perl's target/scratchpad and
result in a permanent allocation. Since this is a cold path,
that allocation is pointless, and syswrite() can already write a
substring.
Allowing Perl to cache a large allocation in a cold path only
result in fragmentation and wasted RAM.
write(2) on a regular file won't result in short writes
unless the FS quotas or free space limits are hit, or the buffer
is close to overflowing (e.g. the 0x7ffff000-byte Linux limit).
Since our HTTP server will never buffer that much in RAM,
there's no need to retry syswrite nor rely on the retrying
implicit in IO::Handle->write and the "print" perlop.
---
lib/PublicInbox/HTTP.pm | 30 ++++++------------------------
1 file changed, 6 insertions(+), 24 deletions(-)
diff --git a/lib/PublicInbox/HTTP.pm b/lib/PublicInbox/HTTP.pm
index b2c74cf3..82c2b200 100644
--- a/lib/PublicInbox/HTTP.pm
+++ b/lib/PublicInbox/HTTP.pm
@@ -26,7 +26,6 @@ use Plack::HTTPParser qw(parse_http_request); # XS or pure Perl
use Plack::Util;
use HTTP::Status qw(status_message);
use HTTP::Date qw(time2str);
-use IO::Handle; # ->write
use PublicInbox::DS qw(msg_more);
use PublicInbox::Syscall qw(EPOLLIN EPOLLONESHOT);
use PublicInbox::Tmpfile;
@@ -117,15 +116,6 @@ sub rbuf_process {
$len ? read_input($self, $rbuf) : app_dispatch($self, undef, $rbuf);
}
-# IO::Handle::write returns boolean, this returns bytes written:
-sub xwrite ($$$) {
- my ($fh, $rbuf, $max) = @_;
- my $w = length($$rbuf);
- $w = $max if $w > $max;
- $fh->write($$rbuf, $w) or return;
- $w;
-}
-
sub read_input ($;$) {
my ($self, $rbuf) = @_;
$rbuf //= $self->{rbuf} // (\(my $x = ''));
@@ -138,7 +128,7 @@ sub read_input ($;$) {
while ($len > 0) {
if ($$rbuf ne '') {
- my $w = xwrite($input, $rbuf, $len);
+ my $w = syswrite($input, $$rbuf, $len);
return write_err($self, $len) unless $w;
$len -= $w;
die "BUG: $len < 0 (w=$w)" if $len < 0;
@@ -333,12 +323,6 @@ sub response_write {
}
}
-sub input_tmpfile ($) {
- my $input = tmpfile('http.input', $_[0]->{sock}) or return;
- $input->autoflush(1);
- $input;
-}
-
sub input_prepare {
my ($self, $env) = @_;
my ($input, $len);
@@ -354,24 +338,22 @@ sub input_prepare {
return quit($self, 400) if $hte !~ /\Achunked\z/i;
$len = CHUNK_START;
- $input = input_tmpfile($self);
+ $input = tmpfile('http.input', $self->{sock});
} else {
$len = $env->{CONTENT_LENGTH};
if (defined $len) {
# rfc7230 3.3.3.4
return quit($self, 400) if $len !~ /\A[0-9]+\z/;
-
return quit($self, 413) if $len > $MAX_REQUEST_BUFFER;
- $input = $len ? input_tmpfile($self) : $null_io;
+ $input = $len ? tmpfile('http.input', $self->{sock})
+ : $null_io;
} else {
$input = $null_io;
}
}
# TODO: expire idle clients on ENFILE / EMFILE
- return unless $input;
-
- $env->{'psgi.input'} = $input;
+ $env->{'psgi.input'} = $input // return;
$self->{env} = $env;
$self->{input_left} = $len || 0;
}
@@ -441,7 +423,7 @@ sub read_input_chunked { # unlikely...
# drain the current chunk
until ($len <= 0) {
if ($$rbuf ne '') {
- my $w = xwrite($input, $rbuf, $len);
+ my $w = syswrite($input, $$rbuf, $len);
return write_err($self, "$len chunk") if !$w;
$len -= $w;
if ($len == 0) {
--
2.50.0