During the CSIT work [0] of using PAPI (over socket) for scale tests, there are failures. The symptoms are consistent with either VPP not sending a response (or not receiving the command), or sending responses out of order. The failure happens fairly infrequently per command (say 1 on 10000), but scale tests execute high amount of commands.

It is not clear what is happening on VPP side. Perhaps the cause is the same as for VPP-1753.

The cause is unlikely to be happening in binary APIs, as in CSIT the currently run scale test are using VAT which does not fail.

[0] https://gerrit.fd.io/r/c/csit/+/21876