-
Notifications
You must be signed in to change notification settings - Fork 1.2k
/
mem_based_rate_limiter.go
194 lines (171 loc) · 5.64 KB
/
mem_based_rate_limiter.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
// Unless explicitly stated otherwise all files in this repository are licensed
// under the Apache License Version 2.0.
// This product includes software developed at Datadog (https://www.datadoghq.com/).
// Copyright 2022-present Datadog, Inc.
package ratelimit
import (
"errors"
"runtime"
"runtime/debug"
"sync"
"time"
"github.com/DataDog/datadog-agent/pkg/config"
"github.com/DataDog/datadog-agent/pkg/util/log"
)
// MemBasedRateLimiter is a rate limiter based on memory usage.
// While the high memory limit is reached, MayWait() blocks and try to release memory.
// When the low memory limit is reached, MayWait() blocks once and may try to release memory.
// The memory limits are defined as soft limits.
//
// `memoryRateLimiter` provides a way to dynamically update the rate at which the memory limit
// is checked.
// When the soft limit is reached, we would like to wait and release memory but not block too often.
// `freeOSMemoryRateLimiter` provides a way to dynamically update the rate at which `FreeOSMemory` is
// called when the soft limit is reached.
type MemBasedRateLimiter struct {
telemetry telemetry
memoryUsage memoryUsage
lowSoftLimitRate float64
highSoftLimitRate float64
memoryRateLimiter *geometricRateLimiter
freeOSMemoryRateLimiter *geometricRateLimiter
previousMemoryUsageRate float64
}
type memoryUsage interface {
getMemoryStats() (float64, float64, error)
}
var memBasedRateLimiterTml = newMemBasedRateLimiterTelemetry()
// Ballast is a way to trick the GC. `ballast` is never read or written.
var ballast []byte //nolint:unused
var ballastOnce sync.Once
// BuildMemBasedRateLimiter builds a new instance of *MemBasedRateLimiter
func BuildMemBasedRateLimiter(cfg config.Reader) (*MemBasedRateLimiter, error) {
var memoryUsage memoryUsage
var err error
if memoryUsage, err = newCgroupMemoryUsage(); err == nil {
log.Info("cgroup limits detected")
} else {
memoryUsage = newHostMemoryUsage()
log.Infof("cgroup limits not detected")
log.Debugf("cgroup limits not detected: %v", err)
}
ballastOnce.Do(func() {
ballastSize := cfg.GetInt64("dogstatsd_mem_based_rate_limiter.memory_ballast")
if ballastSize != 0 {
ballast = make([]byte, 0, ballastSize)
log.Infof("ballast size %vMB", ballastSize/1024/1024)
}
})
usage, limit, err := memoryUsage.getMemoryStats()
if err != nil {
return nil, err
}
log.Infof("Memory usage:%v limit:%v", usage, limit)
return NewMemBasedRateLimiter(
memBasedRateLimiterTml,
memoryUsage,
getConfigFloat(cfg, "low_soft_limit"),
getConfigFloat(cfg, "high_soft_limit"),
cfg.GetInt("dogstatsd_mem_based_rate_limiter.go_gc"),
geometricRateLimiterConfig{
getConfigFloat(cfg, "rate_check.min"),
getConfigFloat(cfg, "rate_check.max"),
getConfigFloat(cfg, "rate_check.factor")},
geometricRateLimiterConfig{
getConfigFloat(cfg, "soft_limit_freeos_check.min"),
getConfigFloat(cfg, "soft_limit_freeos_check.max"),
getConfigFloat(cfg, "soft_limit_freeos_check.factor"),
},
)
}
func getConfigFloat(cfg config.Reader, subkey string) float64 {
return cfg.GetFloat64("dogstatsd_mem_based_rate_limiter." + subkey)
}
// NewMemBasedRateLimiter creates a new instance of MemBasedRateLimiter.
func NewMemBasedRateLimiter(
telemetry telemetry,
memoryUsage memoryUsage,
lowSoftLimitRate float64,
highSoftLimitRate float64,
goGC int,
memoryRateLimiter geometricRateLimiterConfig,
freeOSMemoryRateLimiter geometricRateLimiterConfig) (*MemBasedRateLimiter, error) {
// When `SetMemoryLimit` will be available (https://github.com/golang/go/issues/48409),
// SetGCPercent, madvdontneed=1 and debug.FreeOSMemory() can be removed.
if goGC > 0 {
debug.SetGCPercent(goGC)
}
return &MemBasedRateLimiter{
telemetry: telemetry,
memoryUsage: memoryUsage,
lowSoftLimitRate: lowSoftLimitRate,
highSoftLimitRate: highSoftLimitRate,
memoryRateLimiter: newGeometricRateLimiter(memoryRateLimiter),
freeOSMemoryRateLimiter: newGeometricRateLimiter(freeOSMemoryRateLimiter),
}, nil
}
// MayWait waits and tries to release the memory. See MemBasedRateLimiter for more information.
func (m *MemBasedRateLimiter) MayWait() error {
if !m.memoryRateLimiter.keep() {
m.telemetry.incNoWait()
return nil
}
m.telemetry.incWait()
rate, err := m.getMemoryUsageRate()
if err != nil {
return err
}
m.telemetry.setMemoryUsageRate(rate)
if rate, err = m.waitWhileHighLimit(rate); err != nil {
return nil
}
if m.waitOnceLowLimit(rate) {
m.memoryRateLimiter.increaseRate()
} else {
m.memoryRateLimiter.decreaseRate()
}
m.previousMemoryUsageRate = rate
return nil
}
func (m *MemBasedRateLimiter) waitWhileHighLimit(rate float64) (float64, error) {
for rate > m.highSoftLimitRate {
m.memoryRateLimiter.increaseRate()
m.telemetry.incHighLimit()
runtime.GC()
debug.FreeOSMemory()
var err error
if rate, err = m.getMemoryUsageRate(); err != nil {
return 0, err
}
}
return rate, nil
}
func (m *MemBasedRateLimiter) getMemoryUsageRate() (float64, error) {
usage, limit, err := m.memoryUsage.getMemoryStats()
if err != nil {
return 0, err
}
if limit == 0 {
return 0, errors.New("cgroup memory limit is 0")
}
return usage / limit, nil
}
func (m *MemBasedRateLimiter) waitOnceLowLimit(rate float64) bool {
if rate > m.lowSoftLimitRate {
m.telemetry.incLowLimit()
if m.freeOSMemoryRateLimiter.keep() {
runtime.GC()
debug.FreeOSMemory()
m.telemetry.incLowLimitFreeOSMemory()
} else {
time.Sleep(1 * time.Millisecond)
}
if rate > m.previousMemoryUsageRate {
m.freeOSMemoryRateLimiter.increaseRate()
} else {
m.freeOSMemoryRateLimiter.decreaseRate()
}
return true
}
return false
}