title: Invalid table ID error when too many JDBC threads inserting data to TDengine
body: <p>I am working on a project to use many threads to simulate intensive data writing to time-series database. Here it's TDengine.</p>
  <p>When I bump the threads number to 1000 for writing data to TDengine server, the errors return as below:
  java.sql.SQLException: TDengine ERROR (80000600): Invalid table ID</p>
  <p>And some errors return at the same time:
  java.sql.SQLException: TDengine ERROR (80000014): Database not ready</p>
  <p>Total Requests of Writing is 100,000,000, Failed Requests is 19748</p>
  <p>log below:
  04/21 10:44:21.663735 00042155 DND msg:0x7fd7c8001140, app:0xf36233 type:create-table is reput into mwrite queue:0x138eaa0, retry times:0
  04/21 10:44:21.664098 00042352 TDB ERROR vgId:3 failed to get table to insert data, uid 844438318559607 tid 798
  04/21 10:44:21.664140 00042352 TDB ERROR vgId:3 failed to insert data since Invalid table ID</p>
  <p>Seems something wrong in the server side. May I know if someone can help out?</p>
  <p>Thanks,</p>