gettxoutsetinfo returns empty dict on Raspberry Pi 2 #7344

It takes from 5 (shortest) to almost 40 (longest) minutes for bitcoin-cli gettxoutsetinfo to return an empty dict. I noticed this first whilst configuring the Statoshi branch of Bitcoin Core, but went back to install Bitcoin Core (git clone -b v0.11.2 https://github.com/bitcoin/bitcoin.git) to find the same results.

20:10 pi@raspinode:~/bin/bitcoin.orig $ bitcoin-cli gettxoutsetinfo
{
}
20:12 pi@raspinode:~/bin/bitcoin.orig $ bitcoin-cli getinfo
{
    "version" : 110200,
    "protocolversion" : 70002,
    "blocks" : 393193,
    "timeoffset" : 0,
    "connections" : 12,
    "proxy" : "",
    "difficulty" : 113354299801.47113037,
    "testnet" : false,
    "relayfee" : 0.00005000,
    "errors" : ""
}
20:17 pi@raspinode:~/bin/bitcoin.orig $

Raspberry Pi 2 - 1GB memory - 4 core CPU 900MHz - Blockchain on SanDisk Ultra Android microSDXC 128GB up to 80 MB/Sec Class 10

All other RPC calls through bitcoin-cli are answered promptly and correctly. See also issue on jlopp/statoshi https://github.com/jlopp/statoshi/issues/19#issuecomment-171350739

Same bitcoin version, same h/w, ran 4 times, the first time I didn't measure, but the other three were all 7 mins. Don't see a problem.

$ bitcoin-cli getinfo
{
    "version" : 110200,
    "protocolversion" : 70002,
    "walletversion" : 60000,
    "balance" : 0.00000000,
    "blocks" : 393556,
    "timeoffset" : -3,
    "connections" : 4,
    "proxy" : "",
    "difficulty" : 113354299801.47113037,
    "testnet" : false,
    "keypoololdest" : 1446923210,
    "keypoolsize" : 101,
    "paytxfee" : 0.00000000,
    "relayfee" : 0.00005000,
    "errors" : "WARNING: check your network connection, 5 blocks received in the last 4 hours (24 expected)"
}

$ time bitcoin-cli gettxoutsetinfo; time bitcoin-cli gettxoutsetinfo;time bitcoin-cli gettxoutsetinfo;
{
    "height" : 393552,
    "bestblock" : "000000000000000008b1f531b928c1d27d61581d49f672de1b67d1c15330e2b8",
    "transactions" : 8491980,
    "txouts" : 33700542,
    "bytes_serialized" : 1142479068,
    "hash_serialized" : "6e9f737f9b893f06ce833e609407082c9ca0d35b6ce3d68cf8332df25fb0930c",
    "total_amount" : 15088661.13371732
}

real    7m21.845s
user    0m0.030s
sys     0m0.020s
{
    "height" : 393552,
    "bestblock" : "000000000000000008b1f531b928c1d27d61581d49f672de1b67d1c15330e2b8",
    "transactions" : 8491980,
    "txouts" : 33700542,
    "bytes_serialized" : 1142479068,
    "hash_serialized" : "6e9f737f9b893f06ce833e609407082c9ca0d35b6ce3d68cf8332df25fb0930c",
    "total_amount" : 15088661.13371732
}

real    7m20.363s
user    0m0.050s
sys     0m0.010s
{
    "height" : 393552,
    "bestblock" : "000000000000000008b1f531b928c1d27d61581d49f672de1b67d1c15330e2b8",
    "transactions" : 8491980,
    "txouts" : 33700542,
    "bytes_serialized" : 1142479068,
    "hash_serialized" : "6e9f737f9b893f06ce833e609407082c9ca0d35b6ce3d68cf8332df25fb0930c",
    "total_amount" : 15088661.13371732
}

real    7m23.635s
user    0m0.030s
sys     0m0.020s

I tried 6 more times and it never took more than 7m48s.

Interesting. Thanks for taking the trouble. I tried 3 more times your way and got times between 9m56s and 12m34s. Each time with an empty dict as result. The only difference I can see is that my version is compiled with the --disable-wallet option. I'll try tonight to recompile with the wallet option.

Yeah, I should mention that I watched IO and it's usually around 1.6 to 3.6 MB/s with only abuot 100 or so IO requests per second and that I use an actual external SANDisk SSD. Maybe there's better performance consistency on that device for this type of workload. I run both mainnet and testnet on this Pi, both with wallet enabled.

This RPC call is expected to take a lot of time with slow I/O or CPU, it does a linear scan over the UTXO database. It may be that a timeout happens. Try setting this to a higher value when calling bitcoin-cli (option only on 0.12.x and master):

  -rpcclienttimeout=<n>
       Timeout during HTTP requests (default: 900)

I think the timeout issue is a red herring here. An empty gettxoutsetinfo indicates that GetUTXOStats() failed. In that case an error will have been logged, check your debug.log. Most likely there is corruption and you need to reindex.