This changes the behavior, slightly, of gitweb so that it verifies
that the box isn't inundated with before attempting to serve gitweb.
If the box is overloaded, it basically returns a 503 server unavailable
until the load falls below the defined threshold. This helps dramatically
if you have a box that's I/O bound, reaches a certain load and you
don't want gitweb, the I/O hog that it is, increasing the pain the
server is already undergoing.
adds $maxload configuration variable. Default is a load of 300,
which for most cases should never be hit.
Please note this makes the assumption that /proc/loadavg exists
as there is no good way to read load averages on a great number of
platforms [READ: Windows], or that it's reasonably accurate.
Signed-off-by: John 'Warthog9' Hawley <warthog9@xxxxxxxxxxxxxx>
---
gitweb/gitweb.perl | 24 ++++++++++++++++++++++++
1 files changed, 24 insertions(+), 0 deletions(-)
diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index 7e477af..813e48f 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -221,6 +221,11 @@ our %avatar_size = (
'double' => 32
);
+# Used to set the maximum load that we will still respond to gitweb queries.
+# if we exceed this than we do the processing to figure out if there's a mirror
+# and redirect to it, or to just return 503 server busy
+our $maxload = 300;
+
# You define site-wide feature defaults here; override them with
# $GITWEB_CONFIG as necessary.
our %feature = (
@@ -551,6 +556,25 @@ if (-e $GITWEB_CONFIG) {
do $GITWEB_CONFIG_SYSTEM if -e $GITWEB_CONFIG_SYSTEM;
}
+# loadavg throttle
+sub get_loadavg() {
+ my $load;
+ my @loads;
+
+ open($load, '<', '/proc/loadavg') or return 0;
+ @loads = split(/\s+/, scalar <$load>);
+ close($load);
+ return $loads[0];
+}
+
+if (get_loadavg() > $maxload) {
+ print "Content-Type: text/plain\n";
+ print "Status: 503 Excessive load on server\n";
+ print "\n";
+ print "The load average on the server is too high\n";
+ exit 0;
+}
+
# version of the core git binary
our $git_version = qx("$GIT" --version) =~ m/git version (.*)$/ ? $1 : "unknown";
$number_of_git_cmds++;