gcf2 + extsearch: check for unlinked files on Linux

Check for unlinked mmap-ed files via /proc/$PID/maps every 60s
or so.

ExtSearch (extindex) is compatible-enough with Inbox objects to
be wired into the old per-inbox code, but the startup cost is
projected to be much higher down the line when there's >30K
inboxes, so we scan /proc/$PID/maps for deleted files before
unlinking.  With old Inbox objects, it was (and is) simpler to
just kill processes w/o checking due to the low startup cost
(and non-portability of checking).

Reported-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>
Link: https://public-inbox.org/meta/20210921144754.gulkneuulzo27qbw@meerkat.local/

diff --git a/lib/PublicInbox/ExtSearch.pm b/lib/PublicInbox/ExtSearch.pm
index bd301158a6b0a4163cb58073384bf034a5238dda..cd7cba2e88ce217bbc036a1655f479b291304efe 100644 (file)
--- a/lib/PublicInbox/ExtSearch.pm
+++ b/lib/PublicInbox/ExtSearch.pm
@@ -33,12 +33,18 @@ sub misc {
 # same as per-inbox ->over, for now...
 sub over {
        my ($self) = @_;
-       $self->{over} //= PublicInbox::Over->new("$self->{xpfx}/over.sqlite3");
+       $self->{over} //= do {
+               PublicInbox::Inbox::_cleanup_later($self);
+               PublicInbox::Over->new("$self->{xpfx}/over.sqlite3");
+       };
 }
 
 sub git {
        my ($self) = @_;
-       $self->{git} //= PublicInbox::Git->new("$self->{topdir}/ALL.git");
+       $self->{git} //= do {
+               PublicInbox::Inbox::_cleanup_later($self);
+               PublicInbox::Git->new("$self->{topdir}/ALL.git");
+       };
 }
 
 # returns a hashref of { $NEWSGROUP_NAME => $ART_NO } using the `xref3' table

diff --git a/lib/PublicInbox/Gcf2.pm b/lib/PublicInbox/Gcf2.pm
index 64945ca69cff7fa3cec96539fad0ac0a8f9bfe9d..f546208fa4adeab33016619575e16d9e2b4acb47 100644 (file)
--- a/lib/PublicInbox/Gcf2.pm
+++ b/lib/PublicInbox/Gcf2.pm
@@ -8,6 +8,7 @@ use strict;
 use v5.10.1;
 use PublicInbox::Spawn qw(which popen_rd); # may set PERL_INLINE_DIRECTORY
 use Fcntl qw(LOCK_EX SEEK_SET);
+use Time::HiRes qw(clock_gettime CLOCK_MONOTONIC);
 use IO::Handle; # autoflush
 BEGIN {
        my (%CFG, $c_src);
@@ -96,11 +97,21 @@ sub add_alt ($$) {
        1;
 }
 
-# Usage: $^X -MPublicInbox::Gcf2 -e PublicInbox::Gcf2::loop
+sub have_unlinked_files () {
+       # FIXME: port gcf2-like over to git.git so we won't need to
+       # deal with libgit2
+       return 1 if $^O ne 'linux';
+       open my $fh, '<', "/proc/$$/maps" or return;
+       while (<$fh>) { return 1 if /\.(?:idx|pack) \(deleted\)$/ }
+       undef;
+}
+
+# Usage: $^X -MPublicInbox::Gcf2 -e PublicInbox::Gcf2::loop [EXPIRE-TIMEOUT]
 # (see lib/PublicInbox/Gcf2Client.pm)
-sub loop () {
+sub loop (;$) {
+       my $exp = $_[0] || $ARGV[0] || 60; # seconds
        my $gcf2 = new();
-       my %seen;
+       my (%seen, $check_at);
        STDERR->autoflush(1);
        STDOUT->autoflush(1);
 
@@ -116,6 +127,7 @@ sub loop () {
 
                        $gcf2 = new();
                        %seen = ($git_dir => add_alt($gcf2,"$git_dir/objects"));
+                       $check_at = clock_gettime(CLOCK_MONOTONIC) + $exp;
 
                        if ($gcf2->cat_oid(1, $oid)) {
                                warn "I: $$ $oid found after retry\n";
@@ -123,6 +135,14 @@ sub loop () {
                                warn "W: $$ $oid missing after retry\n";
                                print "$oid missing\n"; # mimic git-cat-file
                        }
+               } else { # check expiry to deal with deleted pack files
+                       my $now = clock_gettime(CLOCK_MONOTONIC);
+                       $check_at //= $now + $exp;
+                       if ($now > $check_at && have_unlinked_files()) {
+                               undef $check_at;
+                               $gcf2 = new();
+                               %seen = ();
+                       }
                }
        }
 }

diff --git a/lib/PublicInbox/Git.pm b/lib/PublicInbox/Git.pm
index 5ef1db2f8c5da5fd94bf70e57255173f0ba16e3c..cf51239f1906c3863058198e7a175514f289b3b8 100644 (file)
--- a/lib/PublicInbox/Git.pm
+++ b/lib/PublicInbox/Git.pm
@@ -12,7 +12,7 @@ use v5.10.1;
 use parent qw(Exporter);
 use POSIX ();
 use IO::Handle; # ->autoflush
-use Errno qw(EINTR EAGAIN);
+use Errno qw(EINTR EAGAIN ENOENT);
 use File::Glob qw(bsd_glob GLOB_NOSORT);
 use File::Spec ();
 use Time::HiRes qw(stat);
@@ -523,6 +523,20 @@ sub manifest_entry {
        $ent;
 }
 
+sub cleanup_if_unlinked {
+       my ($self) = @_;
+       return cleanup($self) if $^O ne 'linux';
+       # Linux-specific /proc/$PID/maps access
+       # TODO: support this inside git.git
+       for my $fld (qw(pid pid_c)) {
+               my $pid = $self->{$fld} // next;
+               open my $fh, '<', "/proc/$pid/maps" or next;
+               while (<$fh>) {
+                       return cleanup($self) if /\.(?:idx|pack) \(deleted\)$/;
+               }
+       }
+}
+
 1;
 __END__
 =pod

diff --git a/lib/PublicInbox/Inbox.pm b/lib/PublicInbox/Inbox.pm
index 20f8c88489fcb8057e43817eef238c5e9fe9e3a8..02ffc7be3bef74e1d4c8738856c59f8f89c5d811 100644 (file)
--- a/lib/PublicInbox/Inbox.pm
+++ b/lib/PublicInbox/Inbox.pm
@@ -22,8 +22,15 @@ my $CLEANUP = {}; # string(inbox) -> inbox
 
 sub git_cleanup ($) {
        my ($self) = @_;
-       my $git = $self->{git} or return;
-       $git->cleanup;
+       if ($self->isa(__PACKAGE__)) {
+               # normal Inbox; low startup cost, and likely to have many
+               # many so this keeps process/pipe counts in check
+               $self->{git}->cleanup if $self->{git};
+       } else {
+               # ExtSearch, high startup cost if ->ALL, and probably
+               # only one per-daemon, so teardown only if required:
+               $self->git->cleanup_if_unlinked;
+       }
 }
 
 sub cleanup_task () {