(Almost?) fixes https://emqx.atlassian.net/browse/EMQX-9637
During the course of performance tests comparing the performance of
e5.0.3 and e4.4.16 regarding the webhook bridge in sync mode, we
observed that the throughput in e5.0.3 (sync) was much lower than in
e4.4.16: ~ 9 k msgs / s vs. ~ 50 k msgs / s, respectively.
Analyzing `observer_cli` output, we noticed that a lot of the time
both buffer workers and ehttpc processes was spent in `ets:info/2`.
That function was called to check the size of the inflight table when
updating metrics and checking if the inflight table was full. Other
uses of `ets:info/2` were contained inside the arguments to some
`?tp/2` macro usages (https://github.com/kafka4beam/snabbkaffe/pull/60).
By using a specific record to track the size of the table, we managed
to improve the bridge performance to ~ 45 k msgs / s in sync mode.
8aa7c014e7