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distclient: fix deadlock between server and distclient #257
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This patch makes the distClient mutex locking/unlocking more fine
grained to avoid having the distClient mutex locked when calling
server.[Get|Update]PeerMap
This should fix this deadlock:
during some HA tests, stopping/starting various torusd processes, noticed that the other `torusd` and `torusblk` were all blocked. I got a stacktrace of all the processes and I found this possible deadlock (in both the `torusd` and `torusblk` processes).
```
goroutine 87 [semacquire, 53 minutes]:
sync.runtime_Semacquire(0xc820150234)
/usr/local/go/src/runtime/sema.go:47 +0x26
sync.(*Mutex).Lock(0xc820150230)
/usr/local/go/src/sync/mutex.go:83 +0x1c4
github.com/coreos/torus.(*Server).GetPeerMap(0xc820150200, 0x0)
/home/sgotti/golang/src/github.com/coreos/torus/server.go:98 +0x4c
github.com/coreos/torus/distributor.(*distClient).getConn(0xc8202ab180, 0xc8202af4d0, 0x24, 0x0, 0x0)
/home/sgotti/golang/src/github.com/coreos/torus/distributor/client.go:59 +0x146
github.com/coreos/torus/distributor.(*distClient).Check(0xc8202ab180, 0x7ff5c602aaa0, 0xc8217e4ea0, 0xc8202af4d0, 0x24, 0xc82164b800, 0x32, 0x40, 0x0, 0x0, ...)
/home/sgotti/golang/src/github.com/coreos/torus/distributor/client.go:150 +0x76
github.com/coreos/torus/distributor/rebalance.(*rebalancer).Tick(0xc82030d4a0, 0xc820393020, 0x0, 0x0)
/home/sgotti/golang/src/github.com/coreos/torus/distributor/rebalance/tick.go:63 +0x5e5
github.com/coreos/torus/distributor.(*Distributor).rebalanceTicker(0xc8202f2cf0, 0xc82030d500)
/home/sgotti/golang/src/github.com/coreos/torus/distributor/rebalance.go:67 +0x490
created by github.com/coreos/torus/distributor.newDistributor
/home/sgotti/golang/src/github.com/coreos/torus/distributor/distributor.go:69 +0x8fe
goroutine 41 [semacquire, 53 minutes]:
sync.runtime_Semacquire(0xc8202ab194)
/usr/local/go/src/runtime/sema.go:47 +0x26
sync.(*Mutex).Lock(0xc8202ab190)
/usr/local/go/src/sync/mutex.go:83 +0x1c4
github.com/coreos/torus/distributor.(*distClient).onPeerTimeout(0xc8202ab180, 0xc8213556e0, 0x24)
/home/sgotti/golang/src/github.com/coreos/torus/distributor/client.go:40 +0x48
github.com/coreos/torus/distributor.(*distClient).(github.com/coreos/torus/distributor.onPeerTimeout)-fm(0xc8213556e0, 0x24)
/home/sgotti/golang/src/github.com/coreos/torus/distributor/client.go:35 +0x34
github.com/coreos/torus.(*Server).updatePeerMap(0xc820150200)
/home/sgotti/golang/src/github.com/coreos/torus/heartbeat.go:124 +0x4e3
github.com/coreos/torus.(*Server).oneHeartbeat(0xc820150200)
/home/sgotti/golang/src/github.com/coreos/torus/heartbeat.go:100 +0x35b
github.com/coreos/torus.(*Server).heartbeat(0xc820150200, 0xc8202e88a0)
/home/sgotti/golang/src/github.com/coreos/torus/heartbeat.go:69 +0x30
created by github.com/coreos/torus.(*Server).BeginHeartbeat
/home/sgotti/golang/src/github.com/coreos/torus/heartbeat.go:62 +0x4a8
```
Looks like:
goroutine A | goroutine B
---------------------------------------------------------------|------------------------------------------------
calls distClient.getConn |
distClient.getConn takes the distClient.mut lock |
calls server.GetPeerMap |
| oneHearBeat takes the server.infoMut
| calls server.updatePeerMap
| calls the timeoutCallBack: distClient.onPeerTimeout
| distClient.onPeerTimeout blocks trying to take the distClient.mut lock
server.GetPeerMap blocks trying to take server.infoMut lock |
|
👏 Nice catch. |
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This patch makes the distClient mutex locking/unlocking more fine
grained to avoid having the distClient mutex locked when calling
server.[Get|Update]PeerMap
This should fix this deadlock:
during some HA tests, stopping/starting various torusd processes, noticed that the other
torusdandtorusblkwere all blocked. I got a stacktrace of all the processes and I found this possible deadlock (in both thetorusdandtorusblkprocesses).Looks like:
Should fix #238