Comment 2 for bug 1897424

In continuous attaching volumes, if the attching volume takes off too long time in nova-compute, and at the same time, another attaching request received by nova-api, nova-api will post RPC call request to nova-compute to create bdm. If the nova-compute won't return the response in time, the nova-api will wait timeout and raise Exception. However, the nova-compute will still create bdm when attaching the previous volume over. The log is the problem log when attaching the second volume.