view: stop storing all MIME objects on large threads

While we try to discard the $smsg (SearchMsg) objects quickly,
they remain referenced via $node (SearchThread::Msg) objects,
which are stored forever in $ctx->{mapping} to cull redundant
words out of subjects in the thread skeleton.

This significantly cuts memory bloat with large search results
with '&x=t'.  Now, the search results overhead of
SearchThread::Msg and linked objects are stable at around 350K
instead of ~7M per response in a rough test (there's more
savings to be had in the same areas).

Several hundred kilobytes is still huge and a large per-client
cost; but it's far better than MEGABYTES per-client.

diff --git a/lib/PublicInbox/View.pm b/lib/PublicInbox/View.pm
index bb49c035d976db7a65b83924a594e4b16c407b99..416cb4a8001a9040afabff4ec606a2ceacb6c67b 100644 (file)
--- a/lib/PublicInbox/View.pm
+++ b/lib/PublicInbox/View.pm
@@ -218,7 +218,7 @@ sub index_entry {
        $rv .= $subj . "\n";
        $rv .= _th_index_lite($mid_raw, \$irt, $id, $ctx);
        my @tocc;
-       my $mime = $smsg->{mime};
+       my $mime = delete $smsg->{mime}; # critical to memory use
        my $hdr = $mime->header_obj;
        my $from = _hdr_names_html($hdr, 'From');
        obfuscate_addrs($obfs_ibx, $from) if $obfs_ibx;