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Fix: fix rand.Seed() duplicate concurrent calls #1958

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merged 3 commits into from
Jul 16, 2022
Merged

Fix: fix rand.Seed() duplicate concurrent calls #1958

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c74fb2f
fix: fix rand.Seed() duplicate concurrent calls
CoolIceV Jul 7, 2022
36addbb
fix: fix rand.Seed() in p2c/loadbalance_test.go
CoolIceV Jul 8, 2022
ed6feb5
Merge remote-tracking branch 'origin/3.0' into fix/randseed
CoolIceV Jul 13, 2022
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2 changes: 1 addition & 1 deletion cluster/loadbalance/p2c/loadbalance.go
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Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,7 @@ var (
)

func init() {
rand.Seed(randSeed())
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@binbin0325 binbin0325 Jul 8, 2022 •
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rand.Seed only need to initialize once

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Yes, I think there should be a sync.Once to initialize the seed globally. Did dubbo-go have it before?

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Each init() is called only once in golang, and I think it is sufficient to ensure that the seed does not change after the program starts running, regardless of the number of times the rand.Seed() is called in the program.

In addition, the imported third-party package may call rand.Seed() even if we only run it once

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@justxuewei justxuewei Jul 8, 2022 •
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Well, the number of initializations of the rand seed is not a very strict limit. This PR looks good for me. BTW, I am saying that initialize the rand seed globally, instead of initialize that in init() function of each package, but it doesn't matter now.

extension.SetLoadbalance(constant.LoadBalanceKeyP2C, newP2CLoadBalance)
}

Expand Down Expand Up @@ -78,7 +79,6 @@ func (l *p2cLoadBalance) Select(invokers []protocol.Invoker, invocation protocol
if len(invokers) == 2 {
i, j = 0, 1
} else {
rand.Seed(randSeed())
i = rand.Intn(len(invokers))
j = i
for i == j {
Expand Down
9 changes: 8 additions & 1 deletion cluster/loadbalance/p2c/loadbalance_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@
package p2c

import (
"math/rand"
"testing"
)

Expand All @@ -37,16 +38,18 @@ import (
func TestLoadBalance(t *testing.T) {
lb := newP2CLoadBalance()
invocation := protoinvoc.NewRPCInvocation("TestMethod", []interface{}{}, nil)
randSeed = func() int64 {
randSeed := func() int64 {
return 0
}

t.Run("no invokers", func(t *testing.T) {
rand.Seed(randSeed())
ivk := lb.Select([]protocol.Invoker{}, invocation)
assert.Nil(t, ivk)
})

t.Run("one invoker", func(t *testing.T) {
rand.Seed(randSeed())
url0, _ := common.NewURL("dubbo://192.168.1.0:20000/com.ikurento.user.UserProvider")

ivkArr := []protocol.Invoker{
Expand All @@ -57,6 +60,7 @@ func TestLoadBalance(t *testing.T) {
})

t.Run("two invokers", func(t *testing.T) {
rand.Seed(randSeed())
ctrl := gomock.NewController(t)
defer ctrl.Finish()

Expand Down Expand Up @@ -86,6 +90,7 @@ func TestLoadBalance(t *testing.T) {
})

t.Run("multiple invokers", func(t *testing.T) {
rand.Seed(randSeed())
ctrl := gomock.NewController(t)
defer ctrl.Finish()

Expand Down Expand Up @@ -117,6 +122,7 @@ func TestLoadBalance(t *testing.T) {
})

t.Run("metrics i not found", func(t *testing.T) {
rand.Seed(randSeed())
ctrl := gomock.NewController(t)
defer ctrl.Finish()

Expand Down Expand Up @@ -144,6 +150,7 @@ func TestLoadBalance(t *testing.T) {
})

t.Run("metrics j not found", func(t *testing.T) {
rand.Seed(randSeed())
ctrl := gomock.NewController(t)
defer ctrl.Finish()

Expand Down
2 changes: 1 addition & 1 deletion registry/servicediscovery/instance/random/random_service_instance_selector.go
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@ import (
)

func init() {
rand.Seed(time.Now().UnixNano())
extension.SetServiceInstanceSelector("random", NewRandomServiceInstanceSelector)
}

Expand All @@ -47,7 +48,6 @@ func (r *RandomServiceInstanceSelector) Select(url *common.URL, serviceInstances
if len(serviceInstances) == 1 {
return serviceInstances[0]
}
rand.Seed(time.Now().UnixNano())
index := rand.Intn(len(serviceInstances))
return serviceInstances[index]
}