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Merge pull request prometheus-community#556 from sysadmind/pg_stat_bgwriter_refactor
refactor pg_stat_bgwriter metrics into standalone collector
2 parents c9b47eb + f44538d commit cb812bb

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7 files changed

+258
-38
lines changed

7 files changed

+258
-38
lines changed

‎CHANGELOG.md

+1
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,6 @@
11
## master / unreleased
22

3+
* [CHANGE] pg_stat_bgwriter counter metrics had the `_total` suffix added #556
34
* [ENHANCEMENT] Add pg_database_size_bytes metric #613
45

56
## 0.10.1 / 2022-01-14

‎README.md

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Original file line numberDiff line numberDiff line change
@@ -41,6 +41,12 @@ This will build the docker image as `prometheuscommunity/postgres_exporter:${bra
4141
* `help`
4242
Show context-sensitive help (also try --help-long and --help-man).
4343

44+
* `collector.database`
45+
Enable the pg_database collector. Default is `enabled`
46+
47+
* `collector.bgwriter`
48+
Enable the pg_stat_bgwriter collector. Default is `enabled`
49+
4450
* `web.listen-address`
4551
Address to listen on for web interface and telemetry. Default is `:9187`.
4652

‎cmd/postgres_exporter/main.go

+5-1
Original file line numberDiff line numberDiff line change
@@ -115,7 +115,11 @@ func main() {
115115

116116
prometheus.MustRegister(exporter)
117117

118-
pe, err := collector.NewPostgresCollector(logger, dsn)
118+
pe, err := collector.NewPostgresCollector(
119+
logger,
120+
dsn,
121+
[]string{},
122+
)
119123
if err != nil {
120124
level.Error(logger).Log("msg", "Failed to create PostgresCollector", "err", err.Error())
121125
os.Exit(1)

‎cmd/postgres_exporter/postgres_exporter.go

-17
Original file line numberDiff line numberDiff line change
@@ -163,23 +163,6 @@ func dumpMaps() {
163163
}
164164

165165
var builtinMetricMaps = map[string]intermediateMetricMap{
166-
"pg_stat_bgwriter": {
167-
map[string]ColumnMapping{
168-
"checkpoints_timed": {COUNTER, "Number of scheduled checkpoints that have been performed", nil, nil},
169-
"checkpoints_req": {COUNTER, "Number of requested checkpoints that have been performed", nil, nil},
170-
"checkpoint_write_time": {COUNTER, "Total amount of time that has been spent in the portion of checkpoint processing where files are written to disk, in milliseconds", nil, nil},
171-
"checkpoint_sync_time": {COUNTER, "Total amount of time that has been spent in the portion of checkpoint processing where files are synchronized to disk, in milliseconds", nil, nil},
172-
"buffers_checkpoint": {COUNTER, "Number of buffers written during checkpoints", nil, nil},
173-
"buffers_clean": {COUNTER, "Number of buffers written by the background writer", nil, nil},
174-
"maxwritten_clean": {COUNTER, "Number of times the background writer stopped a cleaning scan because it had written too many buffers", nil, nil},
175-
"buffers_backend": {COUNTER, "Number of buffers written directly by a backend", nil, nil},
176-
"buffers_backend_fsync": {COUNTER, "Number of times a backend had to execute its own fsync call (normally the background writer handles those even when the backend does its own write)", nil, nil},
177-
"buffers_alloc": {COUNTER, "Number of buffers allocated", nil, nil},
178-
"stats_reset": {COUNTER, "Time at which these statistics were last reset", nil, nil},
179-
},
180-
true,
181-
0,
182-
},
183166
"pg_stat_database": {
184167
map[string]ColumnMapping{
185168
"datid": {LABEL, "OID of a database", nil, nil},

‎collector/collector.go

+29-15
Original file line numberDiff line numberDiff line change
@@ -89,8 +89,21 @@ type PostgresCollector struct {
8989
servers map[string]*server
9090
}
9191

92+
type Option func(*PostgresCollector) error
93+
9294
// NewPostgresCollector creates a new PostgresCollector.
93-
func NewPostgresCollector(logger log.Logger, dsns []string, filters ...string) (*PostgresCollector, error) {
95+
func NewPostgresCollector(logger log.Logger, dsns []string, filters []string, options ...Option) (*PostgresCollector, error) {
96+
p := &PostgresCollector{
97+
logger: logger,
98+
}
99+
// Apply options to customize the collector
100+
for _, o := range options {
101+
err := o(p)
102+
if err != nil {
103+
return nil, err
104+
}
105+
}
106+
94107
f := make(map[string]bool)
95108
for _, filter := range filters {
96109
enabled, exist := collectorState[filter]
@@ -121,48 +134,49 @@ func NewPostgresCollector(logger log.Logger, dsns []string, filters ...string) (
121134
}
122135
}
123136

137+
p.Collectors = collectors
138+
124139
servers := make(map[string]*server)
125140
for _, dsn := range dsns {
126141
s, err := makeServer(dsn)
127142
if err != nil {
128143
return nil, err
129144
}
145+
130146
servers[dsn] = s
131147
}
132148

133-
return &PostgresCollector{
134-
Collectors: collectors,
135-
logger: logger,
136-
servers: servers,
137-
}, nil
149+
p.servers = servers
150+
151+
return p, nil
138152
}
139153

140154
// Describe implements the prometheus.Collector interface.
141-
func (n PostgresCollector) Describe(ch chan<- *prometheus.Desc) {
155+
func (p PostgresCollector) Describe(ch chan<- *prometheus.Desc) {
142156
ch <- scrapeDurationDesc
143157
ch <- scrapeSuccessDesc
144158
}
145159

146160
// Collect implements the prometheus.Collector interface.
147-
func (n PostgresCollector) Collect(ch chan<- prometheus.Metric) {
161+
func (p PostgresCollector) Collect(ch chan<- prometheus.Metric) {
148162
ctx := context.TODO()
149163
wg := sync.WaitGroup{}
150-
wg.Add(len(n.servers))
151-
for _, s := range n.servers {
164+
wg.Add(len(p.servers))
165+
for _, s := range p.servers {
152166
go func(s *server) {
153-
n.subCollect(ctx, s, ch)
167+
p.subCollect(ctx, s, ch)
154168
wg.Done()
155169
}(s)
156170
}
157171
wg.Wait()
158172
}
159173

160-
func (n PostgresCollector) subCollect(ctx context.Context, server *server, ch chan<- prometheus.Metric) {
174+
func (p PostgresCollector) subCollect(ctx context.Context, server *server, ch chan<- prometheus.Metric) {
161175
wg := sync.WaitGroup{}
162-
wg.Add(len(n.Collectors))
163-
for name, c := range n.Collectors {
176+
wg.Add(len(p.Collectors))
177+
for name, c := range p.Collectors {
164178
go func(name string, c Collector) {
165-
execute(ctx, name, c, server, ch, n.logger)
179+
execute(ctx, name, c, server, ch, p.logger)
166180
wg.Done()
167181
}(name, c)
168182
}

‎collector/pg_stat_bgwriter.go

+212
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,212 @@
1+
// Copyright 2021 The Prometheus Authors
2+
// Licensed under the Apache License, Version 2.0 (the "License");
3+
// you may not use this file except in compliance with the License.
4+
// You may obtain a copy of the License at
5+
//
6+
// http://www.apache.org/licenses/LICENSE-2.0
7+
//
8+
// Unless required by applicable law or agreed to in writing, software
9+
// distributed under the License is distributed on an "AS IS" BASIS,
10+
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11+
// See the License for the specific language governing permissions and
12+
// limitations under the License.
13+
14+
package collector
15+
16+
import (
17+
"context"
18+
"time"
19+
20+
"github.com/go-kit/log"
21+
"github.com/prometheus/client_golang/prometheus"
22+
)
23+
24+
func init() {
25+
registerCollector("bgwriter", defaultEnabled, NewPGStatBGWriterCollector)
26+
}
27+
28+
type PGStatBGWriterCollector struct {
29+
}
30+
31+
func NewPGStatBGWriterCollector(logger log.Logger) (Collector, error) {
32+
return &PGStatBGWriterCollector{}, nil
33+
}
34+
35+
const bgWriterSubsystem = "stat_bgwriter"
36+
37+
var statBGWriter = map[string]*prometheus.Desc{
38+
"checkpoints_timed": prometheus.NewDesc(
39+
prometheus.BuildFQName(namespace, bgWriterSubsystem, "checkpoints_timed_total"),
40+
"Number of scheduled checkpoints that have been performed",
41+
[]string{"server"},
42+
prometheus.Labels{},
43+
),
44+
"checkpoints_req": prometheus.NewDesc(
45+
prometheus.BuildFQName(namespace, bgWriterSubsystem, "checkpoints_req_total"),
46+
"Number of requested checkpoints that have been performed",
47+
[]string{"server"},
48+
prometheus.Labels{},
49+
),
50+
"checkpoint_write_time": prometheus.NewDesc(
51+
prometheus.BuildFQName(namespace, bgWriterSubsystem, "checkpoint_write_time_total"),
52+
"Total amount of time that has been spent in the portion of checkpoint processing where files are written to disk, in milliseconds",
53+
[]string{"server"},
54+
prometheus.Labels{},
55+
),
56+
"checkpoint_sync_time": prometheus.NewDesc(
57+
prometheus.BuildFQName(namespace, bgWriterSubsystem, "checkpoint_sync_time_total"),
58+
"Total amount of time that has been spent in the portion of checkpoint processing where files are synchronized to disk, in milliseconds",
59+
[]string{"server"},
60+
prometheus.Labels{},
61+
),
62+
"buffers_checkpoint": prometheus.NewDesc(
63+
prometheus.BuildFQName(namespace, bgWriterSubsystem, "buffers_checkpoint_total"),
64+
"Number of buffers written during checkpoints",
65+
[]string{"server"},
66+
prometheus.Labels{},
67+
),
68+
"buffers_clean": prometheus.NewDesc(
69+
prometheus.BuildFQName(namespace, bgWriterSubsystem, "buffers_clean_total"),
70+
"Number of buffers written by the background writer",
71+
[]string{"server"},
72+
prometheus.Labels{},
73+
),
74+
"maxwritten_clean": prometheus.NewDesc(
75+
prometheus.BuildFQName(namespace, bgWriterSubsystem, "maxwritten_clean_total"),
76+
"Number of times the background writer stopped a cleaning scan because it had written too many buffers",
77+
[]string{"server"},
78+
prometheus.Labels{},
79+
),
80+
"buffers_backend": prometheus.NewDesc(
81+
prometheus.BuildFQName(namespace, bgWriterSubsystem, "buffers_backend_total"),
82+
"Number of buffers written directly by a backend",
83+
[]string{"server"},
84+
prometheus.Labels{},
85+
),
86+
"buffers_backend_fsync": prometheus.NewDesc(
87+
prometheus.BuildFQName(namespace, bgWriterSubsystem, "buffers_backend_fsync_total"),
88+
"Number of times a backend had to execute its own fsync call (normally the background writer handles those even when the backend does its own write)",
89+
[]string{"server"},
90+
prometheus.Labels{},
91+
),
92+
"buffers_alloc": prometheus.NewDesc(
93+
prometheus.BuildFQName(namespace, bgWriterSubsystem, "buffers_alloc_total"),
94+
"Number of buffers allocated",
95+
[]string{"server"},
96+
prometheus.Labels{},
97+
),
98+
"stats_reset": prometheus.NewDesc(
99+
prometheus.BuildFQName(namespace, bgWriterSubsystem, "stats_reset_total"),
100+
"Time at which these statistics were last reset",
101+
[]string{"server"},
102+
prometheus.Labels{},
103+
),
104+
}
105+
106+
func (PGStatBGWriterCollector) Update(ctx context.Context, server *server, ch chan<- prometheus.Metric) error {
107+
db, err := server.GetDB()
108+
if err != nil {
109+
return err
110+
}
111+
112+
row := db.QueryRowContext(ctx,
113+
`SELECT
114+
checkpoints_timed
115+
,checkpoints_req
116+
,checkpoint_write_time
117+
,checkpoint_sync_time
118+
,buffers_checkpoint
119+
,buffers_clean
120+
,maxwritten_clean
121+
,buffers_backend
122+
,buffers_backend_fsync
123+
,buffers_alloc
124+
,stats_reset
125+
FROM pg_stat_bgwriter;`)
126+
127+
var cpt int
128+
var cpr int
129+
var cpwt int
130+
var cpst int
131+
var bcp int
132+
var bc int
133+
var mwc int
134+
var bb int
135+
var bbf int
136+
var ba int
137+
var sr time.Time
138+
139+
err = row.Scan(&cpt, &cpr, &cpwt, &cpst, &bcp, &bc, &mwc, &bb, &bbf, &ba, &sr)
140+
if err != nil {
141+
return err
142+
}
143+
144+
ch <- prometheus.MustNewConstMetric(
145+
statBGWriter["checkpoints_timed"],
146+
prometheus.CounterValue,
147+
float64(cpt),
148+
server.GetName(),
149+
)
150+
ch <- prometheus.MustNewConstMetric(
151+
statBGWriter["checkpoints_req"],
152+
prometheus.CounterValue,
153+
float64(cpr),
154+
server.GetName(),
155+
)
156+
ch <- prometheus.MustNewConstMetric(
157+
statBGWriter["checkpoint_write_time"],
158+
prometheus.CounterValue,
159+
float64(cpwt),
160+
server.GetName(),
161+
)
162+
ch <- prometheus.MustNewConstMetric(
163+
statBGWriter["checkpoint_sync_time"],
164+
prometheus.CounterValue,
165+
float64(cpst),
166+
server.GetName(),
167+
)
168+
ch <- prometheus.MustNewConstMetric(
169+
statBGWriter["buffers_checkpoint"],
170+
prometheus.CounterValue,
171+
float64(bcp),
172+
server.GetName(),
173+
)
174+
ch <- prometheus.MustNewConstMetric(
175+
statBGWriter["buffers_clean"],
176+
prometheus.CounterValue,
177+
float64(bc),
178+
server.GetName(),
179+
)
180+
ch <- prometheus.MustNewConstMetric(
181+
statBGWriter["maxwritten_clean"],
182+
prometheus.CounterValue,
183+
float64(mwc),
184+
server.GetName(),
185+
)
186+
ch <- prometheus.MustNewConstMetric(
187+
statBGWriter["buffers_backend"],
188+
prometheus.CounterValue,
189+
float64(bb),
190+
server.GetName(),
191+
)
192+
ch <- prometheus.MustNewConstMetric(
193+
statBGWriter["buffers_backend_fsync"],
194+
prometheus.CounterValue,
195+
float64(bbf),
196+
server.GetName(),
197+
)
198+
ch <- prometheus.MustNewConstMetric(
199+
statBGWriter["buffers_alloc"],
200+
prometheus.CounterValue,
201+
float64(ba),
202+
server.GetName(),
203+
)
204+
ch <- prometheus.MustNewConstMetric(
205+
statBGWriter["stats_reset"],
206+
prometheus.CounterValue,
207+
float64(sr.Unix()),
208+
server.GetName(),
209+
)
210+
211+
return nil
212+
}

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