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160 lines
5.3 KiB
Perl
Executable file
160 lines
5.3 KiB
Perl
Executable file
#!/usr/bin/perl
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# Plugin to monitor Postgresql memory usage; gives number of blocks
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# read from disk and from memory, showing how much of the database is
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# served from Postgresql's memory buffer.
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#
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# PLEASE NOTE: This plugin may not present the whole truth - the truth
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# may actually be even better than this plugin will show you! That is
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# because Postgresql statistics only considers memory block reads from
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# its own allocated memory. When Postgresql reads from disk, it may
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# actually still be read from memory, but from the _kernel_'s
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# memory. Summarily, your database server may run even better than
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# this plugin will indicate. See
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# http://www.postgresql.org/docs/7.4/interactive/monitoring-stats.html
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# for a (short) description.
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#
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# Copyright Bjørn Ruberg <bjorn@linpro.no> 2006
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#
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# Licenced under GPL v2.
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#
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# Usage:
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#
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# Symlink into /etc/munin/plugins/ and add the monitored
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# database to the filename. e.g.:
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#
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# ln -s /usr/share/munin/plugins/postgres_block_read_ \
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# /etc/munin/plugins/postgres_block_read_SomeDatabase
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# This should, however, be given through autoconf and suggest.
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#
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# If required, give username, password and/or Postgresql server
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# host through environment variables.
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#
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# You must also activate Postgresql statistics. See
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# http://www.postgresql.org/docs/7.4/interactive/monitoring-stats.html
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# for how to enable this. Specifically, the following lines must
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# exist in your postgresql.conf:
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#
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# stats_start_collector = true
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# stats_block_level = true
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#
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#
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# Parameters:
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#
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# config (required)
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#
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# Config variables:
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#
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# dbhost - Which database server to use. Defaults to
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# 'localhost'.
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# dbuser - A Postgresql user account with read permission to
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# the given database. Defaults to
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# 'postgres'. Anyway, Munin must be told which user
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# this plugin should be run as.
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# dbpass - The corresponding password, if
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# applicable. Default to undef. Remember that
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# pg_hba.conf must be configured accordingly.
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#
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# Magic markers
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#%# family=auto
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#%# capabilities=autoconf suggest
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use strict;
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use DBI;
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use Data::Dumper;
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use vars qw ( $debug $suggest $configure $dbh );
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# Need these variables at an early stage to enable
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# autoconf and suggest
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my $dbhost = $ENV{'dbhost'} || ''; # Connect to localhost by default
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my $dbname = $ENV{'dbname'} || 'template1';
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my $dbuser = $ENV{'dbuser'} || 'postgres';
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my $dbpass = $ENV{'dbpass'} || '';
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if (exists $ARGV[0]) {
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if ($ARGV[0] eq 'autoconf') {
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# Check for DBD::Pg
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if (! eval "require DBD::Pg;") {
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print "no (DBD::Pg not found)";
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exit 1;
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}
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# Then we try to detect Postgres presence by connecting to
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# 'template1'.
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my $dsn = "dbi:Pg:dbname=template1";
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$dsn .= ";host=$dbhost" if $dbhost;
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my $tempdbh = DBI->connect ($dsn, $dbuser, $dbpass);
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if ($tempdbh) {
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print "yes\n";
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exit 0;
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} else {
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print "no (Can't connect to given host, please check environment settings)\n";
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exit 1;
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}
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} elsif ($ARGV[0] eq 'debug') {
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# Set debug flag
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$debug = 1;
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} elsif ($ARGV[0] eq 'config') {
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# Set config flag
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$configure = 1;
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} elsif ($ARGV[0] eq 'suggest') {
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# doesn't always work
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my @datasources = DBI->data_sources ('Pg');
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foreach my $dsn (grep !/\=template\d$/, @datasources) {
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(my $db = $dsn) =~ s/^.*=//;
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print "$db\n";
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}
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exit 0;
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}
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}
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# Must do this here, after checking for autoconf/suggest/etc, because the
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# plugin must be able to run before it is linked to the databases.
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my (undef, undef, undef, $dbname) = split (/_/, $0, 4);
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die "No dbname configured (did you make the proper symlink?)" unless $dbname;
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my @datasources = DBI->data_sources ('Pg')
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or die ("Can't read any possible data sources: $?");
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my $dsn = "DBI:Pg:dbname=$dbname";
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$dsn .= ";host=$dbhost" if $dbhost;
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print "#$dsn\n" if $debug;
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my $dbh = DBI->connect ($dsn, $dbuser, $dbpass, {RaiseError =>1});
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unless($dbh) {
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die("Database $dbname\@$dbhost (". $DBI::errstr .")\n");
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}
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if ($configure) {
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print <<EOF;
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graph_title Postgres data reads from $dbname
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graph_args --base 1000
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graph_vlabel Blocks read per \${graph_period}
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graph_category Postgresql
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graph_info Shows number of blocks read from disk and from memory
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from_disk.label Read from disk
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from_disk.info Read from disk
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from_disk.type DERIVE
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from_disk.min 0
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from_disk.draw AREA
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from_memory.label Cached in memory
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from_memory.info Cached in memory
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from_memory.type DERIVE
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from_memory.min 0
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from_memory.draw STACK
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EOF
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} else {
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my $sql = "SELECT (SUM (heap_blks_read) + SUM (idx_blks_read) + ";
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$sql .= "SUM (toast_blks_read) + SUM (tidx_blks_read)) AS disk, ";
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$sql .= "(SUM (heap_blks_hit) +SUM (idx_blks_hit) + ";
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$sql .= "SUM (toast_blks_hit) + SUM (tidx_blks_hit)) AS mem ";
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$sql .= "from pg_statio_user_tables ";
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print "# $sql\n" if $debug;
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my $sth = $dbh->prepare ($sql);
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$sth->execute();
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if ($sth->rows > 0) {
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printf ("# Rows: %d\n", $sth->rows) if $debug;
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my ($disk, $mem) = $sth->fetchrow_array();
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print "from_disk.value $disk\n";
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print "from_memory.value $mem\n";
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}
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}
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