pg_linux_proc is a set of PostgreSQL functions that provides information under /proc directory.
It was developed to simplify OS statistics monitoring without requiring the use of heavyweight solutions like Zabbix and Prometheus.
You can install it to do the usual way shown below.
$ tar xvfj postgresql-16.0.tar.bz2
$ cd postgresql-16.0/contrib
$ git clone https://github.com/s-hironobu/pg_linux_proc.git
$ cd pg_linux_proc
$ make && make install
You must add the line shown below in your postgresql.conf.
shared_preload_libraries = 'pg_linux_proc'
After starting your server, you must issue CREATE EXTENSION statement shown below.
postgres=# CREATE EXTENSION pg_linux_proc;
pg_proc(file) displays information for specified file under /proc.
Here are examples display /proc/version_signature and /proc/misc:
testdb=# select * from pg_proc('version_signature');
pg_proc
---------------------------------------
Ubuntu 5.15.0-94.104-generic 5.15.136+
(1 row)
testdb=# select * from pg_proc('misc');
pg_proc
---------------------
122 vboxuser +
123 vboxguest +
235 autofs +
234 btrfs-control +
124 cpu_dma_latency+
... snip ...
231 snapshot +
242 rfkill +
127 vga_arbiter +
(1 row)
pg_proc_pid() shows running process IDs (PIDs) and their names.
testdb=# select * from pg_proc_pid();
pid | cmdline
--------+---------------------------------------------------------
1 | /sbin/init
2 |
... snip ...
311206 |
311288 |
311330 | /home/vagrant/pgsql/bin/postgres
311331 | postgres: logger
311332 | postgres: checkpointer
311333 | postgres: background writer
311335 | postgres: walwriter
311336 | postgres: autovacuum launcher
311337 | postgres: logical replication launcher
311338 | ./bin/psql
311339 | postgres: vagrant testdb [local] SELECT
(113 rows)
Using these functions, we can access all of information from the /proc directory in principle.
testdb=# select * from pg_proc('311336/cmdline');
pg_proc
--------------------------------
postgres: autovacuum launcher
(1 row)
testdb=# select * from pg_proc('311336/net/arp');
pg_proc
--------------------------------------------------------------------------------
IP address HW type Flags HW address Mask Device+
192.168.128.175 0x1 0x2 bc:d0:74:28:77:c7 * enp0s9+
10.0.2.2 0x1 0x2 52:54:00:12:35:02 * enp0s3+
10.0.2.3 0x1 0x2 52:54:00:12:35:03 * enp0s3+
192.168.128.1 0x1 0x2 4e:3f:c7:9c:8b:7d * enp0s9+
(1 row)
Several functions are available to easily access specific files.
testdb=# select * from pg_os_version();
type | version
-------+-------------------
Linux | 5.15.0-94-generic
(1 row)
testdb=# select * from pg_proc_loadavg();
loadavg1 | loadavg5 | loadavg15 | current_processes | total_processes
----------+----------+-----------+-------------------+-----------------
0 | 0 | 0 | 2 | 140
(1 row)
testdb=# \x
Expanded display is on.
testdb=# select * from pg_proc_diskstats();
-[ RECORD 1 ]---------
major | 7
minor | 0
dev_name | loop0
rd | 61
rd_merged | 0
rd_sec | 794
rd_tm | 28
wr | 0
wr_merged | 0
wr_sec | 0
wr_tm | 0
io | 0
tm | 52
wtm | 28
dis | 0
dis_merged | 0
dis_sec | 0
dis_tm | 0
fl | 0
tm_fl | 0
-[ RECORD 2 ]---------
major | 7
minor | 1
dev_name | loop1
rd | 1714
rd_merged | 0
rd_sec | 99394
rd_tm | 946
wr | 0
wr_merged | 0
... snip ...
testdb=# select * from pg_proc_meminfo();
-[ RECORD 1 ]-----+---------------
memtotal | 980320
memfree | 100340
memavailable | 514156
buffers | 32892
cached | 537552
swapcached | 0
active | 310352
inactive | 387512
active_anon | 5620
inactive_anon | 178724
active_file | 304732
inactive_file | 208788
unevictable | 27784
mlocked | 27784
swaptotal | 0
swapfree | 0
dirty | 24
writeback | 0
anonpages | 155212
mapped | 131576
shmem | 47852
kreclaimable | 55584
slab | 95732
sreclaimable | 55584
sunreclaim | 40148
kernelstack | 2240
pagetables | 3688
nfs_unstable | 0
bounce | 0
writebacktmp | 0
commitlimit | 490160
committed_as | 705980
vmalloctotal | 34359738367
vmallocused | 17028
vmallocchunk | 0
percpu | 1288
hardwarecorrupted | 0
anonhugepages | 0
shmemhugepages | 0
shmempmdmapped | 0
filehugepages | 0
filepmdmapped | 0
cmatotal | 94765210203776
cmafree | 94765191834997
hugepages_total | 0
hugepages_free | 0
hugepages_rsvd | 0
hugepages_surp | 0
hugepagesize | 2048
hugetlb | 0
This shows only cpu items in /proc/stat.
testdb=# select * from pg_proc_stat();
cpu | usr | nice | system | idle | iowait | irq | softirq | steal
------+--------+-------+--------+-----------+--------+-----+---------+-------
cpu0 | 502595 | 13988 | 351453 | 313147621 | 20962 | 0 | 28700 | 0
cpu1 | 420270 | 17765 | 284332 | 304090660 | 14132 | 0 | 78664 | 0
(2 rows)
- 28 Mar, 2024: Version 1.0 Released.
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