Master process crashed after 10 months smooth running

[yourchanges]

@chrislusf Could you help me to find out the problem?

ENV: production
version: 0.71.beta
source tree: https://github.com/chrislusf/seaweedfs/tree/d0dbf6d2eafc0a8758427870a8536f2fe1b82cc6
start args:

nohup ./weed master -ip="0.0.0.0" -defaultReplication="000" -mdir="./meta" &

nohup ./weed volume -max=9999 -mserver="localhost:9333" -dir="./data/v1" -port=5083 -ip="x.x.x.x" -dataCenter="dc1" -rack="rack1" &

the weed server serv 1TB small files, and the master process crashed suddenly, but the volume works well.

crash logs:

I0322 17:36:49 18067 volume_layout.go:193] Volume 129 has 0 replica, less than required 1
I0322 17:36:49 18067 volume_layout.go:169] Volume 129 becomes unwritable
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0xa8 pc=0x8388fe]

goroutine 12 [running]:
panic(0xc7bb40, 0xc8200100f0)
	/opt/dev/go/src/runtime/panic.go:481 +0x3e6
github.com/chrislusf/seaweedfs/weed/topology.(*Topology).UnRegisterDataNode(0xc8201a02a0, 0xc8203b23c0)
	/opt/dev/gowork/src/github.com/chrislusf/seaweedfs/weed/topology/topology_event_handling.go:65 +0x4ae
github.com/chrislusf/seaweedfs/weed/topology.(*Topology).StartRefreshWritableVolumes.func3(0xc8201a02a0)
	/opt/dev/gowork/src/github.com/chrislusf/seaweedfs/weed/topology/topology_event_handling.go:38 +0x3ac
created by github.com/chrislusf/seaweedfs/weed/topology.(*Topology).StartRefreshWritableVolumes
	/opt/dev/gowork/src/github.com/chrislusf/seaweedfs/weed/topology/topology_event_handling.go:42 +0x91

related codes:

func (t *Topology) UnRegisterDataNode(dn *DataNode) {
	for _, v := range dn.GetVolumes() {
		glog.V(0).Infoln("Removing Volume", v.Id, "from the dead volume server", dn)
		vl := t.GetVolumeLayout(v.Collection, v.ReplicaPlacement, v.Ttl)
		vl.SetVolumeUnavailable(dn, v.Id)
	}
	dn.UpAdjustVolumeCountDelta(-dn.GetVolumeCount())
	dn.UpAdjustActiveVolumeCountDelta(-dn.GetActiveVolumeCount())
	dn.UpAdjustMaxVolumeCountDelta(-dn.GetMaxVolumeCount())
	dn.Parent().UnlinkChildNode(dn.Id())
}

It seems that the dn.Parent() is nil, and cased by my disk issue? or any reasons ?

[yourchanges]

or has been fixed?

[chrislusf]

The latest code is very different now. How about try it with the latest version?

[yourchanges]

yeah, I can.

but as you known, maybe we need one year or more to repeat it.

and you can check out this version to check code: https://github.com/chrislusf/seaweedfs/tree/d0dbf6d2eafc0a8758427870a8536f2fe1b82cc6