postgres_exporter issue Accept tcp [::]:9187: accept4: too many open files

[garry-t]

What did you do? start service via systemd What did you expect to see? nothing What did you see instead? Under which circumstances? after sometime system reports too many files opened Environment

• System information:

  Linux 5.15.0-57-generic x86_64

• postgres_exporter version:

  postgres_exporter v0.4.7 (built with go1.10)

• postgres_exporter flags:

--extend.query-path /etc/prometheus/postgres-queries.yml
--web.listen-address :9187

• PostgreSQL version:

  PostgreSQL 13.

• Logs:

  
  Accept error: accept tcp [::]:9187: accept4: too many open files; retrying 
  Oct 27 09:59:38  postgres_exporter[2023066]: panic: runtime error: invalid memory address or nil pointer dereference
  Oct 27 09:59:38  postgres_exporter[2023066]: [signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x4d6b27]
  Oct 27 09:59:38  postgres_exporter[2023066]: goroutine 729574 [running]:
  Oct 27 09:59:38  postgres_exporter[2023066]: database/sql.(*DB).Close(0x0, 0x928d80, 0xc4200d0220)
  Oct 27 09:59:38  postgres_exporter[2023066]: #011/home/travis/.gimme/versions/go1.10.linux.amd64/src/database/sql/sql.go:720 +0x37
  Oct 27 09:59:38  postgres_exporter[2023066]: main.(*Exporter).getDB(0xc4201d8100, 0xc420028011, 0x57, 0xc146f8501e28e979, 0x124d3759cd51a, 0xb940c0)
  Oct 27 09:59:38  postgres_exporter[2023066]: #011/home/travis/gopath/src/github.com/wrouesnel/postgres_exporter/cmd/postgres_exporter/postgres_exporter.go:1040 +0x18a
  Oct 27 09:59:38  postgres_exporter[2023066]: main.(*Exporter).scrape(0xc4201d8100, 0xc429a7f800)
  Oct 27 09:59:38  postgres_exporter[2023066]: #011/home/travis/gopath/src/github.com/wrouesnel/postgres_exporter/cmd/postgres_exporter/postgres_exporter.go:1058 +0xde
  Oct 27 09:59:38 postgres_exporter[2023066]: main.(*Exporter).Collect(0xc4201d8100, 0xc429a7f800)
  Oct 27 09:59:38 postgres_exporter[2023066]: #011/home/travis/gopath/src/github.com/wrouesnel/postgres_exporter/cmd/postgres_exporter/postgres_exporter.go:785 +0x3c
  Oct 27 09:59:38  postgres_exporter[2023066]: github.com/wrouesnel/postgres_exporter/vendor/github.com/prometheus/client_golang/prometheus.(*Registry).Gather.func2(0xc42816d3f0, 0xc429a7f800, 0x92b760, 0xc4201d8100)
  Oct 27 09:59:38  postgres_exporter[2023066]: #011/home/travis/gopath/src/github.com/wrouesnel/postgres_exporter/vendor/github.com/prometheus/client_golang/prometheus/registry.go:383 +0x61
  Oct 27 09:59:38  postgres_exporter[2023066]: created by github.com/wrouesnel/postgres_exporter/vendor/github.com/prometheus/client_golang/prometheus.(*Registry).Gather
  Oct 27 09:59:38  postgres_exporter[2023066]: #011/home/travis/gopath/src/github.com/wrouesnel/postgres_exporter/vendor/github.com/prometheus/client_golang/prometheus/registry.go:381 +0x302
  Oct 27 09:59:38  systemd[1]: prometheus-postgres-exporter.service: Main process exited, code=exited, status=2/INVALIDARGUMENT
  Oct 27 09:59:38  systemd[1]: prometheus-postgres-exporter.service: Failed with result 'exit-code'.

User limits

ulimit -a core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 514704 max locked memory (kbytes, -l) 65536 max memory size (kbytes, -m) unlimited open files (-n) 65535 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 65535 virtual memory (kbytes, -v) unlimited file locks (-x) unlimited

postgress exporter limits

cat /proc/2262062/limits Limit Soft Limit Hard Limit Units
Max cpu time unlimited unlimited seconds
Max file size unlimited unlimited bytes
Max data size unlimited unlimited bytes
Max stack size 8388608 unlimited bytes
Max core file size 0 unlimited bytes
Max resident set unlimited unlimited bytes
Max processes 514704 514704 processes Max open files 100 100 files
Max locked memory 65536 65536 bytes
Max address space unlimited unlimited bytes
Max file locks unlimited unlimited locks
Max pending signals 514704 514704 signals
Max msgqueue size 819200 819200 bytes
Max nice priority 0 0
Max realtime priority 0 0
Max realtime timeout unlimited unlimited us

Please help understand the issue and possible fix. 
Thanks

[garry-t]

Meanwhile I increased Max open files limit 100 -> 1000 I think it is only question of time when it will be reached

[sysadmind]

v0.4.7 is old and unsupported. Please upgrade to v0.14.0 or newer.