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core, eth, miner: improve shutdown synchronisation

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Shutting down geth prints hundreds of annoying error messages in some
cases. The errors appear because the Stop method of eth.ProtocolManager,
miner.Miner and core.TxPool is asynchronous. Left over peer sessions
generate events which are processed after Stop even though the database
has already been closed.

The fix is to make Stop synchronous using sync.WaitGroup.

For eth.ProtocolManager, in order to make use of WaitGroup safe, we need
a way to stop new peer sessions from being added while waiting on the
WaitGroup. The eth protocol Run function now selects on a signaling
channel and adds to the WaitGroup only if ProtocolManager is not
shutting down.

For miner.worker and core.TxPool the number of goroutines is static,
WaitGroup can be used in the usual way without additional
synchronisation.
This commit is contained in:
Felix Lange
2016-03-29 03:08:16 +02:00
parent f821b0188a
commit 56ed6152a1
7 changed files with 101 additions and 70 deletions
Download Patch File Download Diff File Expand all files Collapse all files

60
eth/handler.go
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@ -74,14 +74,14 @@ type ProtocolManager struct {
minedBlockSub event.Subscription
// channels for fetcher, syncer, txsyncLoop
newPeerCh chan *peer
txsyncCh chan *txsync
quitSync chan struct{}
newPeerCh chan *peer
txsyncCh chan *txsync
quitSync chan struct{}
noMorePeers chan struct{}
// wait group is used for graceful shutdowns during downloading
// and processing
wg sync.WaitGroup
quit bool
wg sync.WaitGroup
}
// NewProtocolManager returns a new ethereum sub protocol manager. The Ethereum sub protocol manages peers capable
@ -94,16 +94,17 @@ func NewProtocolManager(config *core.ChainConfig, fastSync bool, networkId int,
}
// Create the protocol manager with the base fields
manager := &ProtocolManager{
networkId: networkId,
fastSync: fastSync,
eventMux: mux,
txpool: txpool,
blockchain: blockchain,
chaindb: chaindb,
peers: newPeerSet(),
newPeerCh: make(chan *peer, 1),
txsyncCh: make(chan *txsync),
quitSync: make(chan struct{}),
networkId: networkId,
fastSync: fastSync,
eventMux: mux,
txpool: txpool,
blockchain: blockchain,
chaindb: chaindb,
peers: newPeerSet(),
newPeerCh: make(chan *peer),
noMorePeers: make(chan struct{}),
txsyncCh: make(chan *txsync),
quitSync: make(chan struct{}),
}
// Initiate a sub-protocol for every implemented version we can handle
manager.SubProtocols = make([]p2p.Protocol, 0, len(ProtocolVersions))
@ -120,8 +121,14 @@ func NewProtocolManager(config *core.ChainConfig, fastSync bool, networkId int,
Length: ProtocolLengths[i],
Run: func(p *p2p.Peer, rw p2p.MsgReadWriter) error {
peer := manager.newPeer(int(version), p, rw)
manager.newPeerCh <- peer
return manager.handle(peer)
select {
case manager.newPeerCh <- peer:
manager.wg.Add(1)
defer manager.wg.Done()
return manager.handle(peer)
case <-manager.quitSync:
return p2p.DiscQuitting
}
},
NodeInfo: func() interface{} {
return manager.NodeInfo()
@ -187,16 +194,25 @@ func (pm *ProtocolManager) Start() {
}
func (pm *ProtocolManager) Stop() {
// Showing a log message. During download / process this could actually
// take between 5 to 10 seconds and therefor feedback is required.
glog.V(logger.Info).Infoln("Stopping ethereum protocol handler...")
pm.quit = true
pm.txSub.Unsubscribe() // quits txBroadcastLoop
pm.minedBlockSub.Unsubscribe() // quits blockBroadcastLoop
close(pm.quitSync) // quits syncer, fetcher, txsyncLoop
// Wait for any process action
// Quit the sync loop.
// After this send has completed, no new peers will be accepted.
pm.noMorePeers <- struct{}{}
// Quit fetcher, txsyncLoop.
close(pm.quitSync)
// Disconnect existing sessions.
// This also closes the gate for any new registrations on the peer set.
// sessions which are already established but not added to pm.peers yet
// will exit when they try to register.
pm.peers.Close()
// Wait for all peer handler goroutines and the loops to come down.
pm.wg.Wait()
glog.V(logger.Info).Infoln("Ethereum protocol handler stopped")