eth hangs on shutdown if blocks are importing

[karalabe]

https://gist.github.com/karalabe/6a70301a0018a3b52cfc7f5a0c17e0dc

This seems to be a regression from #20695

[holiman]

This is still very much happening on our bootnodes..
Some debug printouts

May 14 21:11:38 bootnode-aws-us-east-1-001 geth INFO [05-14|19:11:38.323] Stopping protocol manager
May 14 21:11:38 bootnode-aws-us-east-1-001 geth INFO [05-14|19:11:38.326] protocol manager tx sync loop exiting
May 14 21:11:38 bootnode-aws-us-east-1-001 geth INFO [05-14|19:11:38.326] chainsyncer received quit signal
May 14 21:11:38 bootnode-aws-us-east-1-001 geth INFO [05-14|19:11:38.326] chainsyncer terminating downloader
May 14 21:11:38 bootnode-aws-us-east-1-001 geth INFO [05-14|19:11:38.326] Downloader closed quitCh
May 14 21:11:38 bootnode-aws-us-east-1-001 geth INFO [05-14|19:11:38.326] Downloader calling 'cancel'
May 14 21:11:38 bootnode-aws-us-east-1-001 geth INFO [05-14|19:11:38.326] Downloader waiting for wg 
May 14 21:11:39 bootnode-aws-us-east-1-001 geth INFO [05-14|19:11:39.640] Imported new chain segment blocks=2 txs=280 mgas=19.938 elapsed=8.527s mgasps=2.338 number=10061169 hash="7c40dd…594d8c" age=18h16m59s dirty=253.74MiB
May 14 21:11:40 bootnode-aws-us-east-1-001 geth INFO [05-14|19:11:40.373] Looking for peers peercount=245 tried=69 static=0
May 14 21:11:49 bootnode-aws-us-east-1-001 geth INFO [05-14|19:11:49.789] Imported new chain segment blocks=2 txs=179 mgas=19.960 elapsed=10.148s mgasps=1.967 number=10061171 hash="de0298…13ecb4" age=18h17m2s dirty=254.68MiB
May 14 21:11:50 bootnode-aws-us-east-1-001 geth INFO [05-14|19:11:50.383] Looking for peers peercount=245 tried=120 static=0
May 14 21:12:00 bootnode-aws-us-east-1-001 geth INFO [05-14|19:12:00.390] Looking for peers peercount=245 tried=106 static=0
May 14 21:12:01 bootnode-aws-us-east-1-001 geth INFO [05-14|19:12:01.630] Imported new chain segment blocks=4 txs=408 mgas=29.926 elapsed=11.841s mgasps=2.527 number=10061175 hash="f5025e…b83720" age=18h16m40s dirty=255.93MiB
May 14 21:12:10 bootnode-aws-us-east-1-001 geth INFO [05-14|19:12:10.397] Looking for peers peercount=245 tried=142 static=0
May 14 21:12:15 bootnode-aws-us-east-1-001 geth INFO [05-14|19:12:15.334] Imported new chain segment blocks=3 txs=323 mgas=29.942 elapsed=13.703s mgasps=2.185 number=10061178 hash="2228b3…03370a" age=18h16m15s dirty=255.40MiB

[holiman]

opened a separate ticket