`debug_setHead` causes Clique to hang when period is 0

[albrow]

See #16713 and #19308 for some background.

My PR was closed in favor of a different solution. While I agree that the solution that was merged is cleaner, unfortunately it does not fully address the problem. On the latest commit (at least at the time I opened this issue) debug_setHead causes Clique to stop mining new blocks if it has a period of 0.

I decided to open a new issue because what's happening now is not the same thing as what I originally reported in #16713.

System information

Geth version:

Geth
Version: 1.9.0-unstable
Git Commit: 67fc0377e13416d9a1f8ea32e7d1b0ca89374bf3

OS & Version: MacOS version 10.14.3
Commit hash : 67fc037

Expected behaviour

debug_setHead should work when using Clique with a period of 0.

Actual behaviour

debug_setHead causes Clique to stop mining new blocks.

Steps to reproduce the behaviour

1. Run build/bin/geth --dev --dev.period 0.
2. In a separate terminal session, run build/bin/geth attach /tmp/geth.ipc.
3. Run the following commands in the console (output included here for convenience):

> eth.blockNumber
0
> eth.sendTransaction({from: eth.accounts[0], to: eth.accounts[0], value: "0x0"});
"0x88a1168223a1153ec1cda3fdbb0adeb7e8c3110a6c5d7d937a55460be5768500"
> eth.blockNumber // Sending the transaction resulted in a new block being mined.
1
> eth.sendTransaction({from: eth.accounts[0], to: eth.accounts[0], value: "0x0"});
"0x106ccc6c088f29e3a40dc1b4d90d4570d25eb3f1eb680c190a00774b7f5756c6"
> eth.blockNumber // A second block is mined if we send another transaction
2
> debug.setHead(web3.toHex(1)); // Use debug.setHead to reset to block number 1.
null
> eth.sendTransaction({from: eth.accounts[0], to: eth.accounts[0], value: "0x0"});
"0xb67c83f11784d517080926a05c33b0c991945ec5d835f434ee80dbdee3061a7c"
> eth.blockNumber // Now when we send a transaction it is not mined :/
1
> eth.sendTransaction({from: eth.accounts[0], to: eth.accounts[0], value: "0x0"});
"0x244c753974a1bc8fbd4281aea77a3d2e668d4d1f827c58cf354002258c546b07"
> eth.blockNumber
1

Log output

Here's the full log output during the commands above:

INFO [03-27|17:19:16.079] Maximum peer count                       ETH=25 LES=0 total=25
INFO [03-27|17:19:17.957] Using developer account                  address=0x38c884Aa8CC82596087714E23D046Fe08b2B32b0
INFO [03-27|17:19:17.973] Starting peer-to-peer node               instance=Geth/v1.9.0-unstable-67fc0377/darwin-amd64/go1.12
INFO [03-27|17:19:17.973] Allocated trie memory caches             clean=256.00MiB dirty=256.00MiB
INFO [03-27|17:19:17.973] Allocated cache and file handles         database=/tmp/geth/geth/chaindata cache=512.00MiB handles=5120
INFO [03-27|17:19:18.008] Writing custom genesis block
INFO [03-27|17:19:18.009] Persisted trie from memory database      nodes=13 size=1.81KiB time=205.941µs gcnodes=0 gcsize=0.00B gctime=0s livenodes=1 livesize=0.00B
INFO [03-27|17:19:18.009] Initialised chain configuration          config="{ChainID: 1337 Homestead: 0 DAO: <nil> DAOSupport: false EIP150: 0 EIP155: 0 EIP158: 0 Byzantium: 0 Constantinople: 0  ConstantinopleFix: 0 Engine: clique}"
INFO [03-27|17:19:18.009] Initialising Ethereum protocol           versions="[63 62]" network=1337 dbversion=<nil>
WARN [03-27|17:19:18.009] Upgrade blockchain database version      from=<nil> to=4
INFO [03-27|17:19:18.069] Loaded most recent local header          number=0 hash=603369…c4ffb5 td=1 age=49y11mo1w
INFO [03-27|17:19:18.069] Loaded most recent local full block      number=0 hash=603369…c4ffb5 td=1 age=49y11mo1w
INFO [03-27|17:19:18.069] Loaded most recent local fast block      number=0 hash=603369…c4ffb5 td=1 age=49y11mo1w
INFO [03-27|17:19:18.069] Regenerated local transaction journal    transactions=0 accounts=0
INFO [03-27|17:19:18.070] Stored checkpoint snapshot to disk       number=0 hash=603369…c4ffb5
INFO [03-27|17:19:18.091] started whisper v.6.0
INFO [03-27|17:19:18.091] New local node record                    seq=1 id=c604ffb45fdc7e84 ip=127.0.0.1 udp=0 tcp=58546
INFO [03-27|17:19:18.091] Started P2P networking                   self="enode://6e68cf3051635c565dd22856ef5c87f8e78127555995243163cac9ef6104b8a09c1612e705ea48d89edd0c72d0400b93250e201ecc512f4b0995f04174217f08@127.0.0.1:58546?discport=0"
INFO [03-27|17:19:18.092] IPC endpoint opened                      url=/tmp/geth/geth.ipc
INFO [03-27|17:19:18.092] Transaction pool price threshold updated price=1000000000
INFO [03-27|17:19:18.092] Transaction pool price threshold updated price=1
INFO [03-27|17:19:18.092] Etherbase automatically configured       address=0x38c884Aa8CC82596087714E23D046Fe08b2B32b0
INFO [03-27|17:19:18.092] Commit new mining work                   number=1 sealhash=ae4acc…d2f826 uncles=0 txs=0 gas=0 fees=0 elapsed=104.384µs
INFO [03-27|17:19:18.092] Sealing paused, waiting for transactions
INFO [03-27|17:19:33.074] Setting new local account                address=0x38c884Aa8CC82596087714E23D046Fe08b2B32b0
INFO [03-27|17:19:33.074] Submitted transaction                    fullhash=0x88a1168223a1153ec1cda3fdbb0adeb7e8c3110a6c5d7d937a55460be5768500 recipient=0x38c884Aa8CC82596087714E23D046Fe08b2B32b0
INFO [03-27|17:19:33.074] Commit new mining work                   number=1 sealhash=98ba2f…1b80a5 uncles=0 txs=0 gas=0 fees=0 elapsed=102.27µs
INFO [03-27|17:19:33.074] Sealing paused, waiting for transactions
INFO [03-27|17:19:33.075] Commit new mining work                   number=1 sealhash=f90415…c9200d uncles=0 txs=1 gas=21000 fees=2.1e-14 elapsed=382.561µs
INFO [03-27|17:19:33.075] Successfully sealed new block            number=1 sealhash=f90415…c9200d hash=dce724…4061f8 elapsed=502.166µs
INFO [03-27|17:19:33.075] 🔨 mined potential block                  number=1 hash=dce724…4061f8
INFO [03-27|17:19:33.076] Commit new mining work                   number=2 sealhash=9673da…0fbcb4 uncles=0 txs=0 gas=0     fees=0       elapsed=316.474µs
INFO [03-27|17:19:33.076] Sealing paused, waiting for transactions
INFO [03-27|17:19:38.101] Submitted transaction                    fullhash=0x106ccc6c088f29e3a40dc1b4d90d4570d25eb3f1eb680c190a00774b7f5756c6 recipient=0x38c884Aa8CC82596087714E23D046Fe08b2B32b0
INFO [03-27|17:19:38.101] Commit new mining work                   number=2 sealhash=1fac9e…ba2095 uncles=0 txs=0 gas=0     fees=0       elapsed=70.478µs
INFO [03-27|17:19:38.101] Sealing paused, waiting for transactions
INFO [03-27|17:19:38.101] Commit new mining work                   number=2 sealhash=b9d636…cf1949 uncles=0 txs=1 gas=21000 fees=2.1e-14 elapsed=325.822µs
INFO [03-27|17:19:38.102] Successfully sealed new block            number=2 sealhash=b9d636…cf1949 hash=5447ef…0e7f36 elapsed=527.485µs
INFO [03-27|17:19:38.102] 🔨 mined potential block                  number=2 hash=5447ef…0e7f36
INFO [03-27|17:19:38.102] Commit new mining work                   number=3 sealhash=fe3260…93db86 uncles=0 txs=0 gas=0     fees=0       elapsed=383.433µs
INFO [03-27|17:19:38.102] Sealing paused, waiting for transactions
WARN [03-27|17:19:59.167] Rewinding blockchain                     target=1
INFO [03-27|17:19:59.168] Loaded most recent local header          number=1 hash=dce724…4061f8 td=3 age=26s
INFO [03-27|17:19:59.168] Loaded most recent local full block      number=1 hash=dce724…4061f8 td=3 age=26s
INFO [03-27|17:19:59.168] Loaded most recent local fast block      number=1 hash=dce724…4061f8 td=3 age=26s
INFO [03-27|17:20:03.086] Submitted transaction                    fullhash=0xb67c83f11784d517080926a05c33b0c991945ec5d835f434ee80dbdee3061a7c recipient=0x38c884Aa8CC82596087714E23D046Fe08b2B32b0
INFO [03-27|17:20:03.086] Commit new mining work                   number=2 sealhash=a9cd51…d4c212 uncles=0 txs=0 gas=0     fees=0       elapsed=141.281µs
INFO [03-27|17:20:03.086] Sealing paused, waiting for transactions
INFO [03-27|17:20:03.086] Commit new mining work                   number=2 sealhash=a9cd51…d4c212 uncles=0 txs=0 gas=0     fees=0       elapsed=332.186µs
INFO [03-27|17:20:09.455] Submitted transaction                    fullhash=0x244c753974a1bc8fbd4281aea77a3d2e668d4d1f827c58cf354002258c546b07 recipient=0x38c884Aa8CC82596087714E23D046Fe08b2B32b0
INFO [03-27|17:20:09.455] Commit new mining work                   number=2 sealhash=014960…be5f24 uncles=0 txs=0 gas=0     fees=0       elapsed=81.396µs
INFO [03-27|17:20:09.455] Sealing paused, waiting for transactions
INFO [03-27|17:20:09.455] Commit new mining work                   number=2 sealhash=014960…be5f24 uncles=0 txs=0 gas=0     fees=0       elapsed=279.504µs

Note that for the first two transactions, we see the message 🔨 mined potential block. However, for the last two transactions (after we called debug.setHead) that message no longer appears.

[LogvinovLeon]

@holiman ^

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.