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client: use singleflight to reduce request press #10632

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bdd8fde
use singleflight to reduce request on start
bufferflies Apr 29, 2026
9bd3fed
address check test
bufferflies Apr 29, 2026
5aa61b8
key add url detail
bufferflies Apr 30, 2026
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1 change: 1 addition & 0 deletions client/go.mod
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@ require (
github.com/stretchr/testify v1.9.0
go.uber.org/goleak v1.1.11
go.uber.org/zap v1.24.0
golang.org/x/sync v0.19.0
google.golang.org/grpc v1.75.1
google.golang.org/grpc/examples v0.0.0-20231221225426-4f03f3ff32c9
)
Expand Down
2 changes: 2 additions & 0 deletions client/go.sum
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Expand Up @@ -130,6 +130,8 @@ golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJ
golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sync v0.19.0 h1:vV+1eWNmZ5geRlYjzm2adRgW2/mcpevXNg50YZtPCE4=
golang.org/x/sync v0.19.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
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16 changes: 14 additions & 2 deletions client/servicediscovery/service_discovery.go
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Expand Up @@ -26,6 +26,7 @@ import (
"time"

"go.uber.org/zap"
"golang.org/x/sync/singleflight"
"google.golang.org/grpc"
"google.golang.org/grpc/codes"
healthpb "google.golang.org/grpc/health/grpc_health_v1"
Expand Down Expand Up @@ -443,6 +444,8 @@ type serviceDiscovery struct {
tlsCfg *tls.Config
// Client option.
option *opt.Option

flight singleflight.Group
}
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// NewDefaultServiceDiscovery returns a new default service discovery-based client.
Expand Down Expand Up @@ -474,6 +477,7 @@ func NewServiceDiscovery(
keyspaceID: keyspaceID,
tlsCfg: tlsCfg,
option: option,
flight: singleflight.Group{},
}
pdsd.callbacks.setServiceModeUpdateCallback(serviceModeUpdateCb)
urls = tlsutil.AddrsToURLs(urls, tlsCfg)
Expand Down Expand Up @@ -919,12 +923,16 @@ func (c *serviceDiscovery) getClusterInfo(ctx context.Context, url string, timeo
}
start := time.Now()
defer func() { metrics.InternalCmdDurationGetClusterInfo.Observe(time.Since(start).Seconds()) }()
clusterInfo, err := pdpb.NewPDClient(cc).GetClusterInfo(ctx, &pdpb.GetClusterInfoRequest{})
key := "GetClusterInfo-" + url
res, err, _ := c.flight.Do(key, func() (any, error) {
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@lhy1024 lhy1024 Apr 30, 2026

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singleflight.Do still makes later callers wait for the first same-URL RPC, so their own timeout/cancel may not be respected.

Could we use DoChan + select ctx.Done() to preserve caller deadline semantics?

return pdpb.NewPDClient(cc).GetClusterInfo(ctx, &pdpb.GetClusterInfoRequest{})
})
if err != nil {
metrics.InternalCmdFailedDurationGetClusterInfo.Observe(time.Since(start).Seconds())
attachErr := errors.Errorf("error:%s target:%s status:%s", err, cc.Target(), cc.GetState().String())
return nil, errs.ErrClientGetClusterInfo.Wrap(attachErr).GenWithStackByCause()
}
clusterInfo := res.(*pdpb.GetClusterInfoResponse)
if clusterInfo.GetHeader().GetError() != nil {
metrics.InternalCmdFailedDurationGetClusterInfo.Observe(time.Since(start).Seconds())
attachErr := errors.Errorf("error:%s target:%s status:%s", clusterInfo.GetHeader().GetError().String(), cc.Target(), cc.GetState().String())
Expand All @@ -942,12 +950,16 @@ func (c *serviceDiscovery) getMembers(ctx context.Context, url string, timeout t
}
start := time.Now()
defer func() { metrics.InternalCmdDurationGetMembers.Observe(time.Since(start).Seconds()) }()
members, err := pdpb.NewPDClient(cc).GetMembers(ctx, &pdpb.GetMembersRequest{})
key := "GetMembers-" + url
res, err, _ := c.flight.Do(key, func() (any, error) {
return pdpb.NewPDClient(cc).GetMembers(ctx, &pdpb.GetMembersRequest{})
})
if err != nil {
metrics.InternalCmdFailedDurationGetMembers.Observe(time.Since(start).Seconds())
attachErr := errors.Errorf("error:%s target:%s status:%s", err, cc.Target(), cc.GetState().String())
return nil, errs.ErrClientGetMember.Wrap(attachErr).GenWithStackByCause()
}
members := res.(*pdpb.GetMembersResponse)
if members.GetHeader().GetError() != nil {
metrics.InternalCmdFailedDurationGetMembers.Observe(time.Since(start).Seconds())
attachErr := errors.Errorf("error:%s target:%s status:%s", members.GetHeader().GetError().String(), cc.Target(), cc.GetState().String())
Expand Down
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