From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: X-Spam-Status: No, score=-4.0 required=3.0 tests=ALL_TRUSTED,BAYES_00 shortcircuit=no autolearn=ham autolearn_force=no version=3.4.0 Received: from localhost (dcvr.yhbt.net [127.0.0.1]) by dcvr.yhbt.net (Postfix) with ESMTP id 09F7B1F404; Tue, 27 Feb 2018 22:13:03 +0000 (UTC) From: Eric Wong To: meta@public-inbox.org Cc: "Eric Wong (Contractor, The Linux Foundation)" Subject: [PATCH] searchidx: do not modify Xapian DB while iterating Date: Tue, 27 Feb 2018 22:13:02 +0000 Message-Id: <20180227221302.7308-1-e@80x24.org> List-Id: From: "Eric Wong (Contractor, The Linux Foundation)" Iterating through a list of documents while modifying them does not seem to be supported in Xapian and it can trigger DatabaseCorruptError exceptions. This only worked with past datasets out of dumb luck. With the work-in-progress "v2" public-inbox layout, this problem might become more visible as the "thread skeleton" is partitioned out to a separate, smaller Xapian database. I've reproduced the problem on both Debian 8.x and 9.x with Xapian 1.2.19 (chert backend) and 1.4.3 (glass backend) respectively. --- lib/PublicInbox/SearchIdx.pm | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-) diff --git a/lib/PublicInbox/SearchIdx.pm b/lib/PublicInbox/SearchIdx.pm index 66faed3..5559b39 100644 --- a/lib/PublicInbox/SearchIdx.pm +++ b/lib/PublicInbox/SearchIdx.pm @@ -696,15 +696,22 @@ sub create_ghost { sub merge_threads { my ($self, $winner_tid, $loser_tid) = @_; return if $winner_tid == $loser_tid; - my ($head, $tail) = $self->find_doc_ids('G' . $loser_tid); my $db = $self->{xdb}; - for (; $head != $tail; $head->inc) { - my $docid = $head->get_docid; - my $doc = $db->get_document($docid); - $doc->remove_term('G' . $loser_tid); - $doc->add_term('G' . $winner_tid); - $db->replace_document($docid, $doc); + my $batch_size = 1000; # don't let @ids grow too large to avoid OOM + while (1) { + my ($head, $tail) = $self->find_doc_ids('G' . $loser_tid); + return if $head == $tail; + my @ids; + for (; $head != $tail && @ids < $batch_size; $head->inc) { + push @ids, $head->get_docid; + } + foreach my $docid (@ids) { + my $doc = $db->get_document($docid); + $doc->remove_term('G' . $loser_tid); + $doc->add_term('G' . $winner_tid); + $db->replace_document($docid, $doc); + } } } -- EW