Error polling getblocktemplate {"code":-9,"message":"Core is busy"}

[djapple]

root@ff-virtual-machine:~/pool# node init.js 2017-10-30 11:13:27 [master] Pool spawned on 3 thread(s) 2017-10-30 11:13:28 [unlocker] Started 2017-10-30 11:13:28 [unlocker] No blocks candidates in redis 2017-10-30 11:13:28 [api] API started & listening on port 8117 2017-10-30 11:13:28 [payments] Started 2017-10-30 11:13:28 [payments] No workers' balances reached the minimum payment threshold 2017-10-30 11:13:28 [api] Stat collection finished: 66 ms redis, 159 ms daemon 2017-10-30 11:13:28 [api] Broadcasting to 0 visitors and 0 address lookups 2017-10-30 11:13:33 [api] Stat collection finished: 3 ms redis, 5 ms daemon 2017-10-30 11:13:33 [api] Broadcasting to 0 visitors and 0 address lookups 2017-10-30 11:13:35 [pool] (Thread 3) Error polling getblocktemplate {"code":-9,"message":"Core is busy"} 2017-10-30 11:13:35 [pool] (Thread 3) Could not start pool 2017-10-30 11:13:35 [pool] (Thread 2) Error polling getblocktemplate {"code":-9,"message":"Core is busy"} 2017-10-30 11:13:35 [pool] (Thread 2) Could not start pool 2017-10-30 11:13:35 [pool] (Thread 1) Error polling getblocktemplate {"code":-9,"message":"Core is busy"} 2017-10-30 11:13:35 [pool] (Thread 1) Could not start pool 2017-10-30 11:13:36 [pool] (Thread 2) Error polling getblocktemplate {"code":-9,"message":"Core is busy"} 2017-10-30 11:13:36 [pool] (Thread 3) Error polling getblocktemplate {"code":-9,"message":"Core is busy"} 2017-10-30 11:13:36 [pool] (Thread 1) Error polling getblocktemplate {"code":-9,"message":"Core is busy"}

I encountered this problem, how to solve Other work is normal

ubuntu 14.04 X64 daemon Version: 0.11.1.0 wallet Version: 0.11.1.0

./monerod ./monero-wallet-rpc --wallet-file 2 --password 2 --rpc-bind-port 8082

config.json

"daemon": {
    "host": "127.0.0.1",
    "port": 18081
},

"wallet": {
    "host": "127.0.0.1",
    "port": 8082
},

"redis": {
    "host": "127.0.0.1",
    "port": 6379
},