Deadlock while syncing + JSONRPC

[gavofyork]

syncing hanged when serving jsonrpc call while syncing

[ #869387 9757…4099 ]---[ 28 blk/s | 167 tx/s | 40392121 gas/s  //··· 0/4 peers, #899522, 0+30125 queued ···// mem: 0 bytes db, 126 KiB chain, 23 MiB queue, 302 KiB sync ]
[ #869387 9757…4099 ]---[ 0 blk/s | 0 tx/s | 0 gas/s  //··· 0/4 peers, #899522, 0+30125 queued ···// mem: 0 bytes db, 126 KiB chain, 23 MiB queue, 302 KiB sync ]
[ #869387 9757…4099 ]---[ 0 blk/s | 0 tx/s | 0 gas/s  //··· 0/5 peers, #899522, 0+30125 queued ···// mem: 0 bytes db, 126 KiB chain, 23 MiB queue, 302 KiB sync ]
[ #869387 9757…4099 ]---[ 0 blk/s | 0 tx/s | 0 gas/s  //··· 0/5 peers, #899522, 0+30125 queued ···// mem: 0 bytes db, 126 KiB chain, 23 MiB queue, 302 KiB sync ]
...

was running web3.eth.getBlock, web3.eth.getUncleCountByBlockNumber, web3.eth.getUncleByBlockNumberAndIndex while syncing.

[sammy007]

While syncing several times from scratch I noticed same behaviour when not using jsonrpc.

[gavofyork]

possibly fixed by #1095