From 700c4bef294a792d507f6cfc34dd4dd5427f2a7f Mon Sep 17 00:00:00 2001 From: Joey Hess Date: Tue, 11 Nov 2008 13:40:02 -0500 Subject: let's stop sucking :-) --- doc/todo/avoid_thrashing.mdwn | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) create mode 100644 doc/todo/avoid_thrashing.mdwn (limited to 'doc/todo') diff --git a/doc/todo/avoid_thrashing.mdwn b/doc/todo/avoid_thrashing.mdwn new file mode 100644 index 000000000..6c895e7c9 --- /dev/null +++ b/doc/todo/avoid_thrashing.mdwn @@ -0,0 +1,20 @@ +Problem: Suppose a server has 256 mb ram. Each ikiwiki process needs about +15 mb, before it's loaded the index. (And maybe 25 after, but only one such +process runs at any time). That allows for about 16 ikiwiki processes to +run concurrently on a server, before it starts to swap. Of course, anything +else that runs on the server and eats memory will affect this. + +One could just set `MaxClients 16` in the apache config, but then it's also +limited to 16 clients serving static pages, which is silly. Also, 16 is +optimistic -- 8 might be a saner choice. And then, what if something on the +server decides to eat a lot of memory? Ikiwiki can again overflow memory +and thrash. + +It occurred to me that the ikiwiki cgi wrapper could instead do locking of +its own (say of `.ikiwiki/cgilock`). The wrapper only needs a few kb to +run, and it starts *fast*. So hundreds could be running waiting for a lock +with no ill effects. Crank `MaxClients` up to 256? No problem.. + +And there's no real reason to allow more than one ikiwiki cgi to run at a +time. Since almost all uses of the CGI lock the index, only one can really +be doing anything at a time. --[[Joey]] -- cgit v1.2.3 From d1b22b252481134815b1d02d564b6b9622fe7b4b Mon Sep 17 00:00:00 2001 From: Joey Hess Date: Tue, 11 Nov 2008 15:54:52 -0500 Subject: lockwiki changes * Stop busy-waiting in lockwiki, as this could delay ikiwiki from waking up for up to one second. The bailout code is no longer needed. * Remove support for unused optional wait parameter from lockwiki. --- IkiWiki.pm | 19 +++---------------- debian/changelog | 8 ++++++++ doc/todo/avoid_thrashing.mdwn | 2 ++ po/ikiwiki.pot | 10 +++++----- 4 files changed, 18 insertions(+), 21 deletions(-) (limited to 'doc/todo') diff --git a/IkiWiki.pm b/IkiWiki.pm index dc9b66344..d949566d8 100644 --- a/IkiWiki.pm +++ b/IkiWiki.pm @@ -1280,8 +1280,7 @@ sub indexlink () { #{{{ my $wikilock; -sub lockwiki (;$) { #{{{ - my $wait=@_ ? shift : 1; +sub lockwiki () { #{{{ # Take an exclusive lock on the wiki to prevent multiple concurrent # run issues. The lock will be dropped on program exit. if (! -d $config{wikistatedir}) { @@ -1289,20 +1288,8 @@ sub lockwiki (;$) { #{{{ } open($wikilock, '>', "$config{wikistatedir}/lockfile") || error ("cannot write to $config{wikistatedir}/lockfile: $!"); - if (! flock($wikilock, 2 | 4)) { # LOCK_EX | LOCK_NB - if ($wait) { - debug("wiki seems to be locked, waiting for lock"); - my $wait=600; # arbitrary, but don't hang forever to - # prevent process pileup - for (1..$wait) { - return if flock($wikilock, 2 | 4); - sleep 1; - } - error("wiki is locked; waited $wait seconds without lock being freed (possible stuck process or stale lock?)"); - } - else { - return 0; - } + if (! flock($wikilock, 2)) { # LOCK_EX + error("failed to get lock"); } return 1; } #}}} diff --git a/debian/changelog b/debian/changelog index dfc5de2d4..2088b07ec 100644 --- a/debian/changelog +++ b/debian/changelog @@ -14,6 +14,14 @@ ikiwiki (2.69) UNRELEASED; urgency=low * tag: Normalize tagbase so leading/trailing slashes in it don't break things. * bzr: Fix dates for recentchanges. + * Avoid multiple ikiwiki cgi processes piling up, eating all memory, + and thrashing, by making the cgi wrapper wait on a cgilock. + If you had to set apache's MaxClients low to avoid ikiwiki thrashing your + server, you can now turn it up to a high value. + * Stop busy-waiting in lockwiki, as this could delay ikiwiki from waking up + for up to one second. The bailout code is no longer needed after above + change. + * Remove support for unused optional wait parameter from lockwiki. -- Joey Hess Thu, 06 Nov 2008 16:01:00 -0500 diff --git a/doc/todo/avoid_thrashing.mdwn b/doc/todo/avoid_thrashing.mdwn index 6c895e7c9..45b11d872 100644 --- a/doc/todo/avoid_thrashing.mdwn +++ b/doc/todo/avoid_thrashing.mdwn @@ -18,3 +18,5 @@ with no ill effects. Crank `MaxClients` up to 256? No problem.. And there's no real reason to allow more than one ikiwiki cgi to run at a time. Since almost all uses of the CGI lock the index, only one can really be doing anything at a time. --[[Joey]] + +[[done]] diff --git a/po/ikiwiki.pot b/po/ikiwiki.pot index 34fa5e65b..8cf3853e0 100644 --- a/po/ikiwiki.pot +++ b/po/ikiwiki.pot @@ -8,7 +8,7 @@ msgid "" msgstr "" "Project-Id-Version: PACKAGE VERSION\n" "Report-Msgid-Bugs-To: \n" -"POT-Creation-Date: 2008-11-07 12:23-0500\n" +"POT-Creation-Date: 2008-11-11 15:36-0500\n" "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n" "Last-Translator: FULL NAME \n" "Language-Team: LANGUAGE \n" @@ -910,19 +910,19 @@ msgstr "" #. translators: The first parameter is a filename, and the second is #. translators: a (probably not translated) error message. -#: ../IkiWiki/Wrapper.pm:79 +#: ../IkiWiki/Wrapper.pm:93 #, perl-format msgid "failed to write %s: %s" msgstr "" #. translators: The parameter is a C filename. -#: ../IkiWiki/Wrapper.pm:135 +#: ../IkiWiki/Wrapper.pm:150 #, perl-format msgid "failed to compile %s" msgstr "" #. translators: The parameter is a filename. -#: ../IkiWiki/Wrapper.pm:155 +#: ../IkiWiki/Wrapper.pm:170 #, perl-format msgid "successfully generated %s" msgstr "" @@ -969,7 +969,7 @@ msgstr "" msgid "preprocessing loop detected on %s at depth %i" msgstr "" -#: ../IkiWiki.pm:1685 +#: ../IkiWiki.pm:1672 msgid "yes" msgstr "" -- cgit v1.2.3