Stay on memory pool when I sending multiple transaction from bitcoin wallet I run the bitcoin client 0.17.1 on my ubuntu 18.04 desktop. I have some balance in my wallet. Also my client is fully synced.I have face the wallet conflict. When I send multiple transaction at once(without time gap). Happen two things.


Some transaction is confirmed and completed successfully 
Some transaction is stay on the memory pool for a long time. And the status is show as 0/unconfirmed, in memory pool


If I send transaction with some of time gap, no problems is existing. Also I mention that I already used bumpfee RPC. But transaction stay on the unconfirmed stage.

Note: I give the proper fee for every transaction
Bitcoin Core has locks in place that will stop multiple calls to build a transaction to be executed in parallel. Instead, they will be executed sequentially, as the lock gets relinquished by the previous call. So, the other thing that comes to mind is that there are limits to the ancestry set of transactions that may be submitted to the mempool at the same time.

Your own node's mempool will not accept more than 25 transactions or more than 101 kB in total transaction size that are chained/interdependent in some fashion. Your wallet will attempt to rebroadcast transactions to your own mempool every thirty minutes or so, so even when some of the ancestors of your transactions get confirmed, it may take a while for the others to be relayed to the network.

What you can do: If you're sending a very large number of transactions, e.g. more than 25 per block, you should split up your balance across a greater number of UTXOs, so that you can create a larger count of independent transactions.