Files
seaweedFS/weed/pb/grpc_client_server.go
Chris Lu 5b86d33c3c Fix worker reconnection race condition causing context canceled errors (#7825)
* Fix worker reconnection race condition causing context canceled errors

Fixes #7824

This commit fixes critical connection stability issues between admin server
and workers that manifested as rapid reconnection cycles with 'context canceled'
errors, particularly after 24+ hours of operation in containerized environments.

Root Cause:
-----------
Race condition where TWO goroutines were calling stream.Recv() on the same
gRPC bidirectional stream concurrently:

1. sendRegistrationSync() started a goroutine that calls stream.Recv()
2. handleIncoming() also calls stream.Recv() in a loop

Per gRPC specification, only ONE goroutine can call Recv() on a stream at a
time. Concurrent Recv() calls cause undefined behavior, manifesting as
'context canceled' errors and stream corruption.

The race occurred during worker reconnection:
- Sometimes sendRegistrationSync goroutine read the registration response first (success)
- Sometimes handleIncoming read it first, causing sendRegistrationSync to timeout
- This left the stream in an inconsistent state, triggering 'context canceled' error
- The error triggered rapid reconnection attempts, creating a reconnection storm

Why it happened after 24 hours:
Container orchestration systems (Docker Swarm/Kubernetes) periodically restart
pods. Over time, workers reconnect multiple times. Each reconnection had a chance
of hitting the race condition. Eventually the race manifested and caused the
connection storm.

Changes:
--------

weed/worker/client.go:
- Start handleIncoming and handleOutgoing goroutines BEFORE sending registration
- Use sendRegistration() instead of sendRegistrationSync()
- Ensures only ONE goroutine (handleIncoming) calls stream.Recv()
- Eliminates race condition entirely

weed/admin/dash/worker_grpc_server.go:
- Clean up old connection when worker reconnects with same ID
- Cancel old connection context to stop its goroutines
- Prevents resource leaks and stale connection accumulation

Impact:
-------
Before: Random 'context canceled' errors during reconnection, rapid reconnection
        cycles, resource leaks, requires manual restart to recover
After:  Reliable reconnection, single Recv() goroutine, proper cleanup,
        stable operation over 24+ hours

Testing:
--------
Build verified successful with no compilation errors.

How to reproduce the bug:
1. Start admin server and worker
2. Restart admin server (simulates container recreation)
3. Worker reconnects
4. Race condition may manifest, causing 'context canceled' error
5. Observe rapid reconnection cycles in logs

The fix is backward compatible and requires no configuration changes.

* Add MaxConnectionAge to gRPC server for Docker Swarm DNS handling

- Configure MaxConnectionAge and MaxConnectionAgeGrace for gRPC server
- Expand error detection in shouldInvalidateConnection for better cache invalidation
- Add connection lifecycle logging for debugging

* Add topology validation and nil-safety checks

- Add validation guards in UpdateTopology to prevent invalid updates
- Add nil-safety checks in rebuildIndexes
- Add GetDiskCount method for diagnostic purposes

* Fix worker registration race condition

- Reorder goroutine startup in WorkerStream to prevent race conditions
- Add defensive cleanup in unregisterWorker with panic-safe channel closing

* Add comprehensive topology update logging

- Enhance UpdateTopologyInfo with detailed logging of datacenter/node/disk counts
- Add metrics logging for topology changes

* Add periodic diagnostic status logging

- Implement topologyStatusLoop running every 5 minutes
- Add logTopologyStatus function reporting system metrics
- Run as background goroutine in maintenance manager

* Enhance master client connection logging

- Add connection timing logs in tryConnectToMaster
- Add reconnection attempt counting in KeepConnectedToMaster
- Improve diagnostic visibility for connection issues

* Remove unused sendRegistrationSync function

- Function is no longer called after switching to asynchronous sendRegistration
- Contains the problematic concurrent stream.Recv() pattern that caused race conditions
- Cleanup as suggested in PR review

* Clarify comment for channel closing during disconnection

- Improve comment to explain why channels are closed and their effect
- Make the code more self-documenting as suggested in PR review

* Address code review feedback: refactor and improvements

- Extract topology counting logic to shared helper function
  CountTopologyResources() to eliminate duplication between
  topology_management.go and maintenance_integration.go

- Use gRPC status codes for more robust error detection in
  shouldInvalidateConnection(), falling back to string matching
  for transport-level errors

- Add recover wrapper for channel close consistency in
  cleanupStaleConnections() to match unregisterWorker() pattern

* Update grpc_client_server.go

* Fix data race on lastSeen field access

- Add mutex protection around conn.lastSeen = time.Now() in WorkerStream method
- Ensures thread-safe access consistent with cleanupStaleConnections

* Fix goroutine leaks in worker reconnection logic

- Close streamExit in reconnect() before creating new connection
- Close streamExit in attemptConnection() when sendRegistration fails
- Prevents orphaned handleOutgoing/handleIncoming goroutines from previous connections
- Ensures proper cleanup of goroutines competing for shared outgoing channel

* Minor cleanup improvements for consistency and clarity

- Remove redundant string checks in shouldInvalidateConnection that overlap with gRPC status codes
- Add recover block to Stop() method for consistency with other channel close operations
- Maintains valuable DNS and transport-specific error detection while eliminating redundancy

* Improve topology update error handling

- Return descriptive errors instead of silently preserving topology for invalid updates
- Change nil topologyInfo case to return 'rejected invalid topology update: nil topologyInfo'
- Change empty DataCenterInfos case to return 'rejected invalid topology update: empty DataCenterInfos (had X nodes, Y disks)'
- Keep existing glog.Warningf calls but append error details to logs before returning errors
- Allows callers to distinguish rejected updates and handle them appropriately

* Refactor safe channel closing into helper method

- Add safeCloseOutgoingChannel helper method to eliminate code duplication
- Replace repeated recover blocks in Stop, unregisterWorker, and cleanupStaleConnections
- Improves maintainability and ensures consistent error handling across all channel close operations
- Maintains same panic recovery behavior with contextual source identification

* Make connection invalidation string matching case-insensitive

- Convert error string to lowercase once for all string.Contains checks
- Improves robustness by catching error message variations from different sources
- Eliminates need for separate 'DNS resolution' and 'dns' checks
- Maintains same error detection coverage with better reliability

* Clean up warning logs in UpdateTopology to avoid duplicating error text

- Remove duplicated error phrases from glog.Warningf messages
- Keep concise contextual warnings that don't repeat the fmt.Errorf content
- Maintain same error returns for backward compatibility

* Add robust validation to prevent topology wipeout during master restart

- Reject topology updates with 0 nodes when current topology has nodes
- Prevents transient empty topology from overwriting valid state
- Improves resilience during master restart scenarios
- Maintains backward compatibility for legitimate empty topology updates
2025-12-19 19:02:56 -08:00

371 lines
12 KiB
Go

package pb
import (
"context"
"fmt"
"math/rand/v2"
"net/http"
"strconv"
"strings"
"sync"
"time"
"github.com/google/uuid"
"github.com/seaweedfs/seaweedfs/weed/util/request_id"
"google.golang.org/grpc/metadata"
"github.com/seaweedfs/seaweedfs/weed/glog"
"github.com/seaweedfs/seaweedfs/weed/pb/volume_server_pb"
"github.com/seaweedfs/seaweedfs/weed/util"
"google.golang.org/grpc"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/keepalive"
"google.golang.org/grpc/status"
"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
"github.com/seaweedfs/seaweedfs/weed/pb/master_pb"
"github.com/seaweedfs/seaweedfs/weed/pb/mq_pb"
"github.com/seaweedfs/seaweedfs/weed/pb/worker_pb"
)
const (
Max_Message_Size = 1 << 30 // 1 GB
// gRPC keepalive settings - must be consistent between client and server
GrpcKeepAliveTime = 60 * time.Second // ping interval when no activity
GrpcKeepAliveTimeout = 20 * time.Second // ping timeout
// Connection recycling for Docker Swarm environments
// Forces connections to be recycled periodically to handle DNS changes
GrpcMaxConnectionAge = 5 * time.Minute // max time a connection may exist
GrpcMaxConnectionAgeGrace = 30 * time.Second // grace period for RPCs to complete
)
var (
// cache grpc connections
grpcClients = make(map[string]*versionedGrpcClient)
grpcClientsLock sync.Mutex
)
type versionedGrpcClient struct {
*grpc.ClientConn
version int
errCount int
}
func init() {
http.DefaultTransport.(*http.Transport).MaxIdleConnsPerHost = 1024
http.DefaultTransport.(*http.Transport).MaxIdleConns = 1024
}
func NewGrpcServer(opts ...grpc.ServerOption) *grpc.Server {
var options []grpc.ServerOption
options = append(options,
grpc.KeepaliveParams(keepalive.ServerParameters{
Time: GrpcKeepAliveTime, // server pings client if no activity for this long
Timeout: GrpcKeepAliveTimeout, // ping timeout
MaxConnectionAge: GrpcMaxConnectionAge, // max connection age for Docker Swarm DNS refresh
MaxConnectionAgeGrace: GrpcMaxConnectionAgeGrace, // grace period for in-flight RPCs
}),
grpc.KeepaliveEnforcementPolicy(keepalive.EnforcementPolicy{
MinTime: GrpcKeepAliveTime, // min time a client should wait before sending a ping
PermitWithoutStream: true,
}),
grpc.MaxRecvMsgSize(Max_Message_Size),
grpc.MaxSendMsgSize(Max_Message_Size),
grpc.MaxConcurrentStreams(1000), // Allow more concurrent streams
grpc.InitialWindowSize(16*1024*1024), // 16MB initial window
grpc.InitialConnWindowSize(16*1024*1024), // 16MB connection window
grpc.MaxHeaderListSize(8*1024*1024), // 8MB header list limit
grpc.UnaryInterceptor(requestIDUnaryInterceptor()),
)
for _, opt := range opts {
if opt != nil {
options = append(options, opt)
}
}
return grpc.NewServer(options...)
}
func GrpcDial(ctx context.Context, address string, waitForReady bool, opts ...grpc.DialOption) (*grpc.ClientConn, error) {
// opts = append(opts, grpc.WithBlock())
// opts = append(opts, grpc.WithTimeout(time.Duration(5*time.Second)))
var options []grpc.DialOption
options = append(options,
// grpc.WithTransportCredentials(insecure.NewCredentials()),
grpc.WithDefaultCallOptions(
grpc.MaxCallSendMsgSize(Max_Message_Size),
grpc.MaxCallRecvMsgSize(Max_Message_Size),
grpc.WaitForReady(waitForReady),
),
grpc.WithKeepaliveParams(keepalive.ClientParameters{
Time: GrpcKeepAliveTime, // client ping server if no activity for this long
Timeout: GrpcKeepAliveTimeout, // ping timeout
PermitWithoutStream: true,
}))
for _, opt := range opts {
if opt != nil {
options = append(options, opt)
}
}
return grpc.DialContext(ctx, address, options...)
}
func getOrCreateConnection(address string, waitForReady bool, opts ...grpc.DialOption) (*versionedGrpcClient, error) {
grpcClientsLock.Lock()
defer grpcClientsLock.Unlock()
existingConnection, found := grpcClients[address]
if found {
glog.V(3).Infof("gRPC cache hit for %s (version %d)", address, existingConnection.version)
return existingConnection, nil
}
glog.V(2).Infof("Creating new gRPC connection to %s", address)
ctx := context.Background()
grpcConnection, err := GrpcDial(ctx, address, waitForReady, opts...)
if err != nil {
return nil, fmt.Errorf("fail to dial %s: %v", address, err)
}
vgc := &versionedGrpcClient{
grpcConnection,
rand.Int(),
0,
}
grpcClients[address] = vgc
glog.V(2).Infof("New gRPC connection established to %s (version %d)", address, vgc.version)
return vgc, nil
}
func requestIDUnaryInterceptor() grpc.UnaryServerInterceptor {
return func(
ctx context.Context,
req interface{},
info *grpc.UnaryServerInfo,
handler grpc.UnaryHandler,
) (interface{}, error) {
// Get request ID from incoming metadata
var reqID string
if incomingMd, ok := metadata.FromIncomingContext(ctx); ok {
if idList := incomingMd.Get(request_id.AmzRequestIDHeader); len(idList) > 0 {
reqID = idList[0]
}
}
if reqID == "" {
reqID = uuid.New().String()
}
// Store request ID in context for handlers to access
ctx = request_id.Set(ctx, reqID)
// Also set outgoing context so handlers making downstream gRPC calls
// will automatically propagate the request ID
ctx = metadata.AppendToOutgoingContext(ctx, request_id.AmzRequestIDHeader, reqID)
// Set trailer with request ID for response
grpc.SetTrailer(ctx, metadata.Pairs(request_id.AmzRequestIDHeader, reqID))
return handler(ctx, req)
}
}
// shouldInvalidateConnection checks if an error indicates the cached connection should be invalidated
func shouldInvalidateConnection(err error) bool {
if err == nil {
return false
}
// Check gRPC status codes first (more reliable)
if s, ok := status.FromError(err); ok {
code := s.Code()
switch code {
case codes.Unavailable, codes.Canceled, codes.DeadlineExceeded, codes.Aborted, codes.Internal:
return true
}
}
// Fall back to string matching for transport-level errors not captured by gRPC codes
errStr := err.Error()
errLower := strings.ToLower(errStr)
return strings.Contains(errLower, "transport") ||
strings.Contains(errLower, "connection closed") ||
strings.Contains(errLower, "dns") ||
strings.Contains(errLower, "connection refused") ||
strings.Contains(errLower, "no route to host") ||
strings.Contains(errLower, "network is unreachable") ||
strings.Contains(errLower, "connection reset")
}
// WithGrpcClient In streamingMode, always use a fresh connection. Otherwise, try to reuse an existing connection.
func WithGrpcClient(streamingMode bool, signature int32, fn func(*grpc.ClientConn) error, address string, waitForReady bool, opts ...grpc.DialOption) error {
if !streamingMode {
vgc, err := getOrCreateConnection(address, waitForReady, opts...)
if err != nil {
return fmt.Errorf("getOrCreateConnection %s: %v", address, err)
}
executionErr := fn(vgc.ClientConn)
if executionErr != nil {
if shouldInvalidateConnection(executionErr) {
grpcClientsLock.Lock()
if t, ok := grpcClients[address]; ok {
if t.version == vgc.version {
glog.V(1).Infof("Removing cached gRPC connection to %s due to error: %v", address, executionErr)
vgc.Close()
delete(grpcClients, address)
}
}
grpcClientsLock.Unlock()
}
}
return executionErr
} else {
ctx := context.Background()
if signature != 0 {
// Optimize: Use AppendToOutgoingContext instead of creating new map
ctx = metadata.AppendToOutgoingContext(ctx, "sw-client-id", fmt.Sprintf("%d", signature))
}
grpcConnection, err := GrpcDial(ctx, address, waitForReady, opts...)
if err != nil {
return fmt.Errorf("fail to dial %s: %v", address, err)
}
defer grpcConnection.Close()
executionErr := fn(grpcConnection)
if executionErr != nil {
return executionErr
}
return nil
}
}
func ParseServerAddress(server string, deltaPort int) (newServerAddress string, err error) {
host, port, parseErr := hostAndPort(server)
if parseErr != nil {
return "", fmt.Errorf("server port parse error: %w", parseErr)
}
newPort := int(port) + deltaPort
return util.JoinHostPort(host, newPort), nil
}
func hostAndPort(address string) (host string, port uint64, err error) {
colonIndex := strings.LastIndex(address, ":")
if colonIndex < 0 {
return "", 0, fmt.Errorf("server should have hostname:port format: %v", address)
}
port, err = strconv.ParseUint(address[colonIndex+1:], 10, 64)
if err != nil {
return "", 0, fmt.Errorf("server port parse error: %w", err)
}
return address[:colonIndex], port, err
}
func ServerToGrpcAddress(server string) (serverGrpcAddress string) {
host, port, parseErr := hostAndPort(server)
if parseErr != nil {
glog.Fatalf("server address %s parse error: %v", server, parseErr)
}
grpcPort := int(port) + 10000
return util.JoinHostPort(host, grpcPort)
}
func GrpcAddressToServerAddress(grpcAddress string) (serverAddress string) {
host, grpcPort, parseErr := hostAndPort(grpcAddress)
if parseErr != nil {
glog.Fatalf("server grpc address %s parse error: %v", grpcAddress, parseErr)
}
port := int(grpcPort) - 10000
return util.JoinHostPort(host, port)
}
func WithMasterClient(streamingMode bool, master ServerAddress, grpcDialOption grpc.DialOption, waitForReady bool, fn func(client master_pb.SeaweedClient) error) error {
return WithGrpcClient(streamingMode, 0, func(grpcConnection *grpc.ClientConn) error {
client := master_pb.NewSeaweedClient(grpcConnection)
return fn(client)
}, master.ToGrpcAddress(), waitForReady, grpcDialOption)
}
func WithVolumeServerClient(streamingMode bool, volumeServer ServerAddress, grpcDialOption grpc.DialOption, fn func(client volume_server_pb.VolumeServerClient) error) error {
return WithGrpcClient(streamingMode, 0, func(grpcConnection *grpc.ClientConn) error {
client := volume_server_pb.NewVolumeServerClient(grpcConnection)
return fn(client)
}, volumeServer.ToGrpcAddress(), false, grpcDialOption)
}
func WithOneOfGrpcMasterClients(streamingMode bool, masterGrpcAddresses map[string]ServerAddress, grpcDialOption grpc.DialOption, fn func(client master_pb.SeaweedClient) error) (err error) {
for _, masterGrpcAddress := range masterGrpcAddresses {
err = WithGrpcClient(streamingMode, 0, func(grpcConnection *grpc.ClientConn) error {
client := master_pb.NewSeaweedClient(grpcConnection)
return fn(client)
}, masterGrpcAddress.ToGrpcAddress(), false, grpcDialOption)
if err == nil {
return nil
}
}
return err
}
func WithBrokerGrpcClient(streamingMode bool, brokerGrpcAddress string, grpcDialOption grpc.DialOption, fn func(client mq_pb.SeaweedMessagingClient) error) error {
return WithGrpcClient(streamingMode, 0, func(grpcConnection *grpc.ClientConn) error {
client := mq_pb.NewSeaweedMessagingClient(grpcConnection)
return fn(client)
}, brokerGrpcAddress, false, grpcDialOption)
}
func WithFilerClient(streamingMode bool, signature int32, filer ServerAddress, grpcDialOption grpc.DialOption, fn func(client filer_pb.SeaweedFilerClient) error) error {
return WithGrpcFilerClient(streamingMode, signature, filer, grpcDialOption, fn)
}
func WithGrpcFilerClient(streamingMode bool, signature int32, filerAddress ServerAddress, grpcDialOption grpc.DialOption, fn func(client filer_pb.SeaweedFilerClient) error) error {
return WithGrpcClient(streamingMode, signature, func(grpcConnection *grpc.ClientConn) error {
client := filer_pb.NewSeaweedFilerClient(grpcConnection)
return fn(client)
}, filerAddress.ToGrpcAddress(), false, grpcDialOption)
}
func WithOneOfGrpcFilerClients(streamingMode bool, filerAddresses []ServerAddress, grpcDialOption grpc.DialOption, fn func(client filer_pb.SeaweedFilerClient) error) (err error) {
for _, filerAddress := range filerAddresses {
err = WithGrpcClient(streamingMode, 0, func(grpcConnection *grpc.ClientConn) error {
client := filer_pb.NewSeaweedFilerClient(grpcConnection)
return fn(client)
}, filerAddress.ToGrpcAddress(), false, grpcDialOption)
if err == nil {
return nil
}
}
return err
}
func WithWorkerClient(streamingMode bool, workerAddress string, grpcDialOption grpc.DialOption, fn func(client worker_pb.WorkerServiceClient) error) error {
return WithGrpcClient(streamingMode, 0, func(grpcConnection *grpc.ClientConn) error {
client := worker_pb.NewWorkerServiceClient(grpcConnection)
return fn(client)
}, workerAddress, false, grpcDialOption)
}