Under a full nextest run on loaded machines the legitimately serialized
cross-disk commits in concurrent_resend_same_part_commits_one_generation
exceed the acquire deadline by themselves: observed at the 5s default,
at the 30s production default (#4370), and on CI even at 60s — which is
a hard ceiling, because fast_lock clamps every requested timeout to
MAX_ACQUIRE_TIMEOUT (60s) while the Timeout error still reports the
requested value, so raising the env override higher is a no-op.
Request the full 60s ceiling explicitly and cap the queue depth at three
concurrent resends, bounding the last waiter to two serialized commits
(~12s each on the slowest observed CI runner). Three resends still race
the streaming phase and contend on the commit lock, which is all the
generation-mixing regression (backlog#853) needs; every correctness
assertion is unchanged.
Co-authored-by: heihutu <[email protected]>
