Data race in module on "StageBidderRequest"

[linux019]

I need to access bidder aliases in the RequestWrapper to resolve adapter name (as modules on many stages receive bidder alias, not "bidder core name" = adapter name)
race.log - full log
race.tar.gz - test scripts & config

1. Use pbs.yaml with enabled default module:

external_url: "http://localhost:8000"

metrics:
  prometheus:
    port: 9100
auction_timeouts_ms:
  default: 60000
  max: 600000

compression:
  response:
    enable_gzip: false
  request:
    enable_gzip: false

gdpr:
  enabled: true
  default_value: "0"

adapters:
  ix:
    endpoint: https://00000.lb.indexww.com/pbs
    disabled: false
  rubicon:
    disabled: false
    endpoint: "https://exapi-us-east.rubiconproject.com/a/api/exchange"

hooks:
  enabled: true
  modules:
    prebid:
      ortb2blocking:
        enabled: true



  host_execution_plan:
    endpoints:
      "/openrtb2/auction":
        stages:

          bidder_request:
            groups:
              timeout: 100 #ms
              hook_sequence:
                - module_code: "prebid.ortb2blocking"
                  hook_impl_code: "prebid.ortb2blocking"

2. Add following code here to read bidder aliases to the demo module
   

   prebid-server/modules/prebid/ortb2blocking/hook_bidderrequest.go

   Line 22 in 4870355

	if reqExt, err := payload.Request.GetRequestExt(); err == nil {
		_ = reqExt.GetPrebid().Aliases
	}

or apply patch with git apply file.patch (in the project root directory)
4. run server with enabled race detector go run -race main.go
5. use "run.sh" from the archive to run 50 parallel requests (it needs to run several times the shell script with curl to get a data race)
6. result

==================
WARNING: DATA RACE
Write at 0x00c000342c08 by goroutine 703:
  github.com/prebid/prebid-server/v2/openrtb_ext.(*RequestWrapper).GetRequestExt()
      github.com/prebid/prebid-server/v2/openrtb_ext/request_wrapper.go:127 +0xa4
  github.com/prebid/prebid-server/v2/modules/prebid/ortb2blocking.Module.HandleBidderRequestHook()
      github.com/prebid/prebid-server/v2/modules/prebid/ortb2blocking/module.go:25 +0x85
  github.com/prebid/prebid-server/v2/modules/prebid/ortb2blocking.(*Module).HandleBidderRequestHook()
      <autogenerated>:1 +0x16d
  github.com/prebid/prebid-server/v2/hooks/hookexecution.(*hookExecutor).ExecuteBidderRequestStage.func1()
      github.com/prebid/prebid-server/v2/hooks/hookexecution/executor.go:199 +0x161
  github.com/prebid/prebid-server/v2/hooks/hookexecution.executeHook[go.shape.interface { HandleBidderRequestHook(context.Context, github.com/prebid/prebid-server/v2/hooks/hookstage.ModuleInvocationContext, github.com/prebid/prebid-server/v2/hooks/hookstage.BidderRequestPayload) (github.com/prebid/prebid-server/v2/hooks/hookstage.HookResult[github.com/prebid/prebid-server/v2/hooks/hookstage.BidderRequestPayload], error) },go.shape.struct { Request *github.com/prebid/prebid-server/v2/openrtb_ext.RequestWrapper; Bidder string }].func1()
      github.com/prebid/prebid-server/v2/hooks/hookexecution/execution.go:108 +0x1e6

Previous read at 0x00c000342c08 by goroutine 576:
  github.com/prebid/prebid-server/v2/openrtb_ext.(*RequestWrapper).rebuildRequestExt()
      github.com/prebid/prebid-server/v2/openrtb_ext/request_wrapper.go:285 +0x3c
  github.com/prebid/prebid-server/v2/openrtb_ext.(*RequestWrapper).RebuildRequest()
      github.com/prebid/prebid-server/v2/openrtb_ext/request_wrapper.go:203 +0x9a
  github.com/prebid/prebid-server/v2/exchange.(*bidderAdapter).requestBid()
      github.com/prebid/prebid-server/v2/exchange/bidder.go:150 +0x24b
  github.com/prebid/prebid-server/v2/exchange.(*validatedBidder).requestBid()
      github.com/prebid/prebid-server/v2/exchange/bidder_validate_bids.go:35 +0x216
  github.com/prebid/prebid-server/v2/exchange.(*exchange).getAllBids.func1()
      github.com/prebid/prebid-server/v2/exchange/exchange.go:720 +0x98b
  github.com/prebid/prebid-server/v2/exchange.(*exchange).getAllBids.(*exchange).recoverSafely.func2()
      github.com/prebid/prebid-server/v2/exchange/exchange.go:829 +0x1c4
  github.com/prebid/prebid-server/v2/exchange.(*exchange).getAllBids.gowrap1()
      github.com/prebid/prebid-server/v2/exchange/exchange.go:751 +0x104

Goroutine 703 (running) created at:
  github.com/prebid/prebid-server/v2/hooks/hookexecution.executeHook[go.shape.interface { HandleBidderRequestHook(context.Context, github.com/prebid/prebid-server/v2/hooks/hookstage.ModuleInvocationContext, github.com/prebid/prebid-server/v2/hooks/hookstage.BidderRequestPayload) (github.com/prebid/prebid-server/v2/hooks/hookstage.HookResult[github.com/prebid/prebid-server/v2/hooks/hookstage.BidderRequestPayload], error) },go.shape.struct { Request *github.com/prebid/prebid-server/v2/openrtb_ext.RequestWrapper; Bidder string }]()
      github.com/prebid/prebid-server/v2/hooks/hookexecution/execution.go:105 +0x390
  github.com/prebid/prebid-server/v2/hooks/hookexecution.executeGroup[go.shape.interface { HandleBidderRequestHook(context.Context, github.com/prebid/prebid-server/v2/hooks/hookstage.ModuleInvocationContext, github.com/prebid/prebid-server/v2/hooks/hookstage.BidderRequestPayload) (github.com/prebid/prebid-server/v2/hooks/hookstage.HookResult[github.com/prebid/prebid-server/v2/hooks/hookstage.BidderRequestPayload], error) },go.shape.struct { Request *github.com/prebid/prebid-server/v2/openrtb_ext.RequestWrapper; Bidder string }].func1()
      github.com/prebid/prebid-server/v2/hooks/hookexecution/execution.go:78 +0x22c
  github.com/prebid/prebid-server/v2/hooks/hookexecution.executeGroup[go.shape.interface { HandleBidderRequestHook(context.Context, github.com/prebid/prebid-server/v2/hooks/hookstage.ModuleInvocationContext, github.com/prebid/prebid-server/v2/hooks/hookstage.BidderRequestPayload) (github.com/prebid/prebid-server/v2/hooks/hookstage.HookResult[github.com/prebid/prebid-server/v2/hooks/hookstage.BidderRequestPayload], error) },go.shape.struct { Request *github.com/prebid/prebid-server/v2/openrtb_ext.RequestWrapper; Bidder string }].gowrap1()
      github.com/prebid/prebid-server/v2/hooks/hookexecution/execution.go:79 +0xf8

Goroutine 576 (running) created at:
  github.com/prebid/prebid-server/v2/exchange.(*exchange).getAllBids()
      github.com/prebid/prebid-server/v2/exchange/exchange.go:751 +0x18f
  github.com/prebid/prebid-server/v2/exchange.(*exchange).HoldAuction()
      github.com/prebid/prebid-server/v2/exchange/exchange.go:378 +0x2624
  github.com/prebid/prebid-server/v2/endpoints/openrtb2.(*endpointDeps).Auction()
      github.com/prebid/prebid-server/v2/endpoints/openrtb2/auction.go:264 +0x1adb
  github.com/prebid/prebid-server/v2/endpoints/openrtb2.(*endpointDeps).Auction-fm()
      <autogenerated>:1 +0x73
  github.com/julienschmidt/httprouter.(*Router).ServeHTTP()
      github.com/julienschmidt/httprouter@v1.3.0/router.go:387 +0xf0b
  github.com/prebid/prebid-server/v2/router.(*Router).ServeHTTP()
      <autogenerated>:1 +0x64
  github.com/prebid/prebid-server/v2/router.SupportCORS.(*Cors).Handler.func2()
      github.com/rs/cors@v1.8.2/cors.go:231 +0x2f1
  net/http.HandlerFunc.ServeHTTP()
      net/http/server.go:2166 +0x47
  github.com/prebid/prebid-server/v2/router.NoCache.ServeHTTP()
      github.com/prebid/prebid-server/v2/router/router.go:119 +0x421
  github.com/prebid/prebid-server/v2/router.(*NoCache).ServeHTTP()
      <autogenerated>:1 +0x69
  net/http.serverHandler.ServeHTTP()
      net/http/server.go:3137 +0x2a1
  net/http.(*conn).serve()
      net/http/server.go:2039 +0x13c4
  net/http.(*Server).Serve.gowrap3()
      net/http/server.go:3285 +0x4f
==================
==================
WARNING: DATA RACE
Read at 0x00c00219dde0 by goroutine 841:
  github.com/prebid/prebid-server/v2/openrtb_ext.(*RequestWrapper).GetRequestExt()
      github.com/prebid/prebid-server/v2/openrtb_ext/request_wrapper.go:128 +0x10a
  github.com/prebid/prebid-server/v2/modules/prebid/ortb2blocking.Module.HandleBidderRequestHook()

[linux019]

Moreover just running tests with enabled race detector go test -race ./... produces a lot of warnings in "exchange"

WARNING: DATA RACE
Read at 0x00c00053ae48 by goroutine 647:
  net/http.Header.Clone()
      /usr/lib/go/src/net/http/header.go:101 +0x5697
  github.com/prebid/prebid-server/v2/exchange.(*bidderAdapter).requestBid()
      exchange/bidder.go:174 +0x6b8
  github.com/prebid/prebid-server/v2/exchange.(*exchange).getAllBids.func1()
      exchange/exchange.go:733 +0x98b
  github.com/prebid/prebid-server/v2/exchange.(*exchange).getAllBids.(*exchange).recoverSafely.func2()
      exchange/exchange.go:842 +0x1c4
  github.com/prebid/prebid-server/v2/exchange.(*exchange).getAllBids.gowrap1()
      exchange/exchange.go:764 +0x104

Previous write at 0x00c00053ae48 by goroutine 648:
  net/http.Header.Clone()
      /usr/lib/go/src/net/http/header.go:114 +0x58d4
  github.com/prebid/prebid-server/v2/exchange.(*bidderAdapter).requestBid()
      exchange/bidder.go:174 +0x6b8

And all OpenRTB structures in https://github.com/prebid/prebid-server/blob/master/openrtb_ext/request_wrapper.go have accessors which modifies internal data on read access and this request wrapper is shared between adapters or hooks which are spawned in goroutines

[SyntaxNode]

Closed accidently during backlog grooming. Reopened.